Acoustic Reproducing Waveguide for Wearable XR Glasses

Abstract

An embodiment of the present disclosure relates to an acoustic waveguide for presenting an audio signal. An apparatus according to an embodiment of the present disclosure may include a waveguide member comprising a hollow body having a first end and a second end. The apparatus may further include an acoustic source disposed at the first end of the waveguide configured to emit at least a first acoustic wave. The apparatus may further include a plurality of acoustic vents disposed on a lower surface of the body of the waveguide, each of the plurality of acoustic vents configured to receive the first acoustic wave and further configured to emit a respective acoustic wave based on the first acoustic wave, each acoustic wave corresponding to a respective point sound source.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63 / 272,561, filed October 27, 2021, the contents of which are incorporated by reference in their entirety herein.

[0002] Field The present disclosure relates generally to a system for presenting one or more audio signals, and more particularly to a head-mounted device for presenting one or more audio signals to a user. [Background technology]

[0003] background Virtual environments are ubiquitous in computing environments, being used in video games (where the virtual environment may represent a game world); maps (where the virtual environment may represent a terrain through which a virtual environment is navigated); simulations (where the virtual environment may simulate a real environment); digital storytelling (where virtual characters may interact with one another in a virtual environment); and many other applications. Modern computer users are generally comfortable perceiving and interacting with virtual environments. However, a user's experience with a virtual environment may be limited by the technology for presenting the virtual environment. For example, conventional displays (e.g., 2D display screens) and audio systems (e.g., fixed speakers) may not be able to realize a virtual environment in a way that creates an engaging, realistic, and immersive experience.

[0004] Virtual reality ("VR"), augmented reality ("AR"), mixed reality ("MR"), and related technologies (collectively "XR") share the ability to present to a user of an XR system sensory information corresponding to a virtual environment represented by data in a computer system. Such systems can provide a uniquely enhanced sense of immersion and presence by combining virtual visual and audio cues with real sights and sounds. It may therefore be desirable to present digital sounds to a user of an XR system as they occur in the user's real environment, i.e., naturally and consistently with the user's expectations for sound. Generally speaking, users expect virtual sounds to take on the acoustic characteristics of the real environment in which they are heard. For example, an XR system user in a large concert hall will expect the virtual sound of the XR system to have a large and spacious sonic quality, and conversely, a user in a small apartment will expect the sound to be more attenuated, close, and immediate. In addition to matching the virtual sounds to the acoustic characteristics of the real and / or virtual environment, the sense of presence is further enhanced by spatializing the virtual sounds. For example, a virtual object may visually fly past the user from behind, and the user may expect the corresponding virtual sound to similarly reflect the spatial movement of the virtual object relative to the user.

[0005] Existing technologies often fail to meet these expectations, such as by presenting virtual audio that does not take into account the user's surroundings or does not correspond to the spatial movement of virtual objects, leading to incongruities that can detract from the user experience. Observations of users of XR systems indicate that while users can be relatively tolerant of visual mismatches (e.g., lighting mismatches) between virtual content and the real environment, they can be more sensitive to auditory mismatches. Our own auditory experience is continually refined throughout our lives, making us acutely aware of how the sounds we hear are affected by our physical environment and we can be overly aware of sounds that do not match such expectations. In XR systems, such mismatches can be unpleasant and can turn an immersive and engaging experience into a gimmicky, mimetic one. In extreme cases, auditory mismatches can cause sickness and other pathological effects, as the inner ear is unable to match auditory stimuli with the corresponding visual cues.

[0006] Rendering virtual audio objects within the user's field of view by an XR system can be challenging, especially when sound is delivered to the user using conventional earphones and / or speakers mounted near the entrance of the user's ear canal. In a real environment, sound is generally received by an individual's ear via a frontal incidence wavefront. The frontal incidence wavefront may interact with the individual's pinna, the outer part of the ear that is visible as a physical body, which may impart a unique acoustic signature to the external sound heard by the individual. If the speaker is mounted on or inside the ear, the sound received by the user may not include this unique acoustic signature, which may detract from the user's immersive XR experience. Furthermore, placing the speaker's audio transducer close to the user's ear may add bulk and weight to the arm of the head-mounted display, which may be uncomfortable for the user's ear to support that weight. Furthermore, some speaker systems are prone to sound leakage, where sound produced by the speaker may be heard by other individuals in the vicinity. Sound leakage is not only annoying to the user and other individuals, but it may also interfere with the user's audio privacy. It may therefore be desirable to provide a speaker system capable of providing a sound input that includes the acoustic signature of the user's pinna with minimal sound leakage. Summary of the Invention [Means for solving the problem]

[0007] overview The embodiments of the present disclosure relate to an acoustic waveguide and a method of use for presenting an audio signal. The acoustic waveguide according to the embodiments of the present disclosure can provide a frontal sound incidence to a user such that the sound perceived by the user can include the acoustic signature of the user's pinna. The embodiments of the present disclosure can also provide minimal sound leakage due to the sound source directivity of the acoustic waveguide. The device according to the embodiments of the present disclosure can include a waveguide member comprising a hollow body having a first end and a second end. The device can further include a sound source disposed at the first end of the waveguide configured to emit at least a first sound wave. The device can further include a plurality of acoustic vents disposed at a lower surface of the body of the waveguide, each of the plurality of acoustic vents configured to receive the first sound wave and further configured to emit a respective sound wave based on the first sound wave, each sound wave corresponding to a respective point sound source.

[0008] An embodiment of the present disclosure may include a head-wearable device. For example, the head-wearable device may include a front frame, a display coupled to the front frame, an arm coupled to the front frame and configured to attach the head-wearable device to a user's head, and an acoustic waveguide. In one or more examples, the acoustic waveguide may include a waveguide member having a hollow body having a first end and a second end, an acoustic source disposed at the first end of the waveguide, and a plurality of acoustic vents disposed on a lower surface of the body of the waveguide, each of the plurality of acoustic vents configured to receive a first acoustic wave and further to emit a respective acoustic wave based on the first acoustic wave, each acoustic wave corresponding to a respective point sound source.

[0009] An embodiment of the present disclosure may include a head-wearable device. For example, the head-wearable device may include a front frame, a display coupled to the front frame, an arm coupled to the front frame and configured to attach the head-wearable device to a user's head, and an acoustic waveguide. In some embodiments, the acoustic waveguide may include an audio source, a decoder coupled to the audio source and configured to generate an audio signal, a digital signal processor (DSP) configured to receive the audio signal from the decoder and generate a beamforming signal, a plurality of acoustic vents disposed on a lower surface of the waveguide, and a plurality of audio transducers. In some embodiments, each audio transducer is disposed within a respective acoustic vent of the plurality of acoustic vents, and each audio transducer receives a discrete output signal that is phase-correlated to generate directional audio waves.

[0010] An embodiment of the present disclosure may include a method for presenting an audio signal. According to one or more embodiments, the method may include emitting one or more acoustic waves of the audio signal via an audio source into a waveguide member of an acoustic waveguide, receiving the one or more acoustic waves at a first acoustic vent, the first acoustic vent being disposed on a lower surface of the waveguide member, generating a first point sound source at the first acoustic vent based on the one or more acoustic waves, receiving the one or more acoustic waves at a second acoustic vent, the second acoustic vent being disposed on a lower surface of the waveguide member, generating a second point sound source at the second acoustic vent based on the one or more acoustic waves, and presenting the first point sound source and the second point sound source. [Brief description of the drawings]

[0011] [Figure 1A] 1A-1C illustrate an exemplary mixed reality environment in accordance with one or more embodiments of the present disclosure. [Figure 1B] 1A-1C illustrate an exemplary mixed reality environment in accordance with one or more embodiments of the present disclosure. [Figure 1C]1A-1C illustrate an exemplary mixed reality environment in accordance with one or more embodiments of the present disclosure.

[0012] [Figure 2A] 2A-2D illustrate components of an example mixed reality system that can be used to generate and interact with a mixed reality environment in accordance with one or more embodiments of the present disclosure. [Figure 2B] 2A-2D illustrate components of an example mixed reality system that can be used to generate and interact with a mixed reality environment in accordance with one or more embodiments of the present disclosure. [Figure 2C] 2A-2D illustrate components of an example mixed reality system that can be used to generate and interact with a mixed reality environment in accordance with one or more embodiments of the present disclosure. [Figure 2D] 2A-2D illustrate components of an example mixed reality system that can be used to generate and interact with a mixed reality environment in accordance with one or more embodiments of the present disclosure.

[0013] [Figure 3A] FIG. 3A illustrates an example mixed reality handheld controller that can be used to provide input to a mixed reality environment, in accordance with one or more embodiments of the present disclosure.

[0014] [Figure 3B] FIG. 3B illustrates an example auxiliary unit that can be used with an example mixed reality system in accordance with one or more embodiments of the present disclosure.

[0015] [Figure 4] FIG. 4 illustrates an example functional block diagram of an example mixed reality system in accordance with one or more embodiments of the present disclosure.

[0016] [Figure 5A]5A-5B illustrate an exemplary acoustic waveguide in accordance with one or more embodiments of the present disclosure. [Figure 5B] 5A-5B illustrate an exemplary acoustic waveguide in accordance with one or more embodiments of the present disclosure.

[0017] [Figure 6A] 6A-6D illustrate an example acoustic waveguide for a mixed reality system in accordance with one or more embodiments of the present disclosure. [Figure 6B] 6A-6D illustrate an example acoustic waveguide for a mixed reality system in accordance with one or more embodiments of the present disclosure. [Figure 6C] 6A-6D illustrate an example acoustic waveguide for a mixed reality system in accordance with one or more embodiments of the present disclosure. [Figure 6D] 6A-6D illustrate an example acoustic waveguide for a mixed reality system in accordance with one or more embodiments of the present disclosure.

[0018] [Figure 7A] FIG. 7A illustrates an example block diagram of a process for operating a speaker system in accordance with one or more embodiments of the present disclosure.

[0019] [Figure 7B] 7B-7D show example sound radiation patterns in accordance with one or more embodiments of the present disclosure. [Figure 7C] 7B-7D show example sound radiation patterns in accordance with one or more embodiments of the present disclosure. [Figure 7D] 7B-7D show example sound radiation patterns in accordance with one or more embodiments of the present disclosure.

[0020] [Figure 8] FIG. 8 illustrates an example acoustic waveguide for a mixed reality system in accordance with one or more embodiments of the present disclosure.

[0021] [Figure 9] FIG. 9 illustrates an example acoustic waveguide for a mixed reality system in accordance with one or more embodiments of the present disclosure.

[0022] [Figure 10A] 10A-10B illustrate an example speaker system for a mixed reality system in accordance with one or more embodiments of the present disclosure. [Figure 10B] 10A-10B illustrate an example speaker system for a mixed reality system in accordance with one or more embodiments of the present disclosure.

[0023] [Figure 11] FIG. 11 illustrates an example block diagram of a process for operating a speaker system in accordance with one or more embodiments of the present disclosure.

[0024] [Figure 12] FIG. 12 illustrates an exemplary mixed reality system in accordance with one or more embodiments of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Detailed Description In the following description of the examples, reference is made to the accompanying drawings which form a part hereof, and which show, by way of illustration, specific examples which may be practiced. It is to be understood that other examples may be used and structural changes may be made without departing from the scope of the disclosed examples. Mixed Reality Environment

[0026] Like all humans, a user of a mixed reality system is present in a real environment, i.e., the three-dimensional portion of the "real world" and all of its contents that are perceptible by the user. For example, the user perceives the real environment using the normal human senses (sight, sound, touch, taste, smell) and interacts with the real environment by moving his or her body within the real environment. Locations in the real environment can be described as coordinates in a coordinate space. For example, the coordinates can include latitude, longitude, and altitude relative to sea level; distances in three orthogonal dimensions from a reference point; or other suitable values. Similarly, a vector can describe a quantity that has a direction and magnitude in a coordinate space.

[0027] The computing device may maintain a representation of the virtual environment, for example, in a memory associated with the device. As used herein, a virtual environment is a computational representation of a three-dimensional space. The virtual environment may include a representation of any objects, actions, signals, parameters, coordinates, vectors, or other properties associated with that space. In some examples, the circuitry (e.g., a processor) of the computing device may maintain and update the state of the virtual environment. That is, the processor may determine the state of the virtual environment at a second time t1 based on data associated with the virtual environment and / or input provided by a user at a first time t0. For example, if an object in the virtual environment is located at a first coordinate at time t0 and has certain programmed physical parameters (e.g., mass, coefficient of friction), input received from the user may indicate that a force should be applied to the object in a directional vector. The processor may apply the laws of kinematics to determine the position of the object at time t1 using basic mechanics. The processor may determine the state of the virtual environment at time t1 using any suitable information known about the virtual environment and / or any suitable input. In maintaining and updating the state of the virtual environment, the processor may execute any suitable software, including software related to creating and deleting virtual objects in the virtual environment; software (e.g., scripts) for defining the behavior of virtual objects or characters in the virtual environment; software for defining the behavior of signals (e.g., audio signals) in the virtual environment; software for creating and updating parameters associated with the virtual environment; software for generating audio signals in the virtual environment; software for handling input and output; software for implementing network operations; software for applying asset data (e.g., animation data for moving virtual objects over time); or many other possibilities.

[0028] An output device, such as a display or speaker, can present any or all aspects of the virtual environment to the user. For example, the virtual environment can include virtual objects (which may include representations of objects such as inanimate objects; people; animals; lights, etc.) that can be presented to the user. The processor can determine a view of the virtual environment (e.g., corresponding to a "camera" having an origin coordinate, a view axis, and a frustum) and render on the display a viewable scene of the virtual environment corresponding to that view. Any suitable rendering technique can be used for this purpose. In some examples, the viewable scene may include only some virtual objects in the virtual environment and exclude certain other virtual objects. Similarly, the virtual environment can include audio aspects that can be presented to the user as one or more audio signals. For example, a virtual object in the virtual environment may generate a sound that originates from the object's position coordinates (e.g., a virtual character may speak or generate a sound effect). Alternatively, the virtual environment may be associated with musical cues or ambient sounds that may or may not be associated with a particular location. The processor can determine an audio signal corresponding to a "listener" coordinate, e.g., an audio signal that corresponds to the synthesis of sounds in the virtual environment and that has been mixed and processed to simulate the audio signal that a listener would hear at the listener coordinate, and present the audio signal to the user via one or more speakers.

[0029] Because the virtual environment exists only as a computational construct, the user cannot directly perceive the virtual environment using normal senses. Instead, the user can only indirectly perceive the virtual environment, for example, as presented to the user by a display, a speaker, a haptic output device, etc. Similarly, the user cannot directly touch, manipulate, or interact with the virtual environment, but can provide input data via an input device or sensor to a processor that can use the device or sensor data to update the virtual environment. For example, a camera sensor can provide optical data indicating that the user is attempting to move an object in the virtual environment, and the processor can use that data to cause the object to respond accordingly in the virtual environment.

[0030] A mixed reality system can present a user with a mixed reality environment ("MRE") that combines aspects of the real environment and the virtual environment, for example, using a see-through display and / or one or more speakers (which may be incorporated, for example, in a wearable head device). In some embodiments, the one or more speakers may be external to the head-mounted wearable unit. As used herein, an MRE is a simultaneous representation of a real environment and a corresponding virtual environment. In some examples, the corresponding real environment and virtual environment share a single coordinate space. In some examples, the real coordinate space and the corresponding virtual coordinate space are related to each other by a transformation matrix (or other suitable representation). Thus, a single coordinate (in some examples, together with the transformation matrix) can define a first location in the real environment and a second corresponding location in the virtual environment, or vice versa.

[0031] In an MRE, a virtual object (e.g., in a virtual environment associated with the MRE) may correspond to a real object (e.g., in a real environment associated with the MRE). For example, if the real environment of the MRE includes a real lamp post (real object) at a location coordinate, the virtual environment of the MRE may include a virtual lamp post (virtual object) at a corresponding location coordinate. As used herein, a real object in combination with a corresponding virtual object constitutes a "mixed reality object." A virtual object need not perfectly match or align with a corresponding real object. In some examples, a virtual object may be a simplified version of a corresponding real object. For example, if a real environment includes a real lamp post, the corresponding virtual object may include a cylinder of approximately the same height and radius as the real lamp post (reflecting that a lamp post may be approximately cylindrical in shape). Simplifying virtual objects in this manner may increase computational efficiency and simplify calculations performed on such virtual objects. Additionally, in some examples of MREs, not all real objects in the real environment are associated with a corresponding virtual object. Similarly, in some instances of the MRE, not all virtual objects in the virtual environment are associated with corresponding real-world objects, i.e., some virtual objects may exist only in the MRE's virtual environment without a real-world counterpart.

[0032] In some examples, virtual objects may have characteristics that are sometimes drastically different from the characteristics of the corresponding real object. For example, a real environment in an MRE may include a green, two-armed cactus (a thorny, inanimate object), while the corresponding virtual object in the MRE may have the characteristics of a green, two-armed virtual character with human facial features and a blank expression. In this example, the virtual object resembles its corresponding real object in certain characteristics (color, number of arms), but other characteristics (facial features, personality) differ from the real object. In this way, virtual objects have the potential to represent real objects in creative, abstract, exaggerated, or imaginative ways, or to give behaviors (e.g., human personality) to otherwise inanimate real objects. In some examples, virtual objects may be purely imaginative creations with no real-world counterpart (e.g., a virtual monster in a virtual environment, possibly in a position that corresponds to an empty space in the real environment).

[0033] Compared to VR systems that present a virtual environment to a user while obscuring the real environment, mixed reality systems that present an MRE offer the advantage that the real environment remains perceptible while the virtual environment is presented. Thus, a user of a mixed reality system can experience and interact with the corresponding virtual environment using visual and audio cues associated with the real environment. By way of example, as discussed above, a user of a VR system may struggle to perceive or interact with virtual objects displayed in a virtual environment because the user cannot directly perceive or interact with the virtual environment, whereas a user of an MR system may find it intuitive and natural to interact with virtual objects by seeing, hearing, and touching the corresponding real objects in their own real environment. This level of interactivity can enhance the sense of immersion, connection, and engagement with the virtual environment. Similarly, by presenting a real environment and a virtual environment simultaneously, a mixed reality system can reduce the negative psychological feelings (e.g., cognitive dissonance) and negative physical feelings (e.g., sickness) associated with a VR system. Mixed reality systems further offer many possibilities for applications that may augment or modify real-world experiences.

[0034] 1A illustrates an exemplary real-world environment 100 in which a user 110 uses a mixed reality system 112. The mixed reality system 112 may include a display (e.g., a see-through display) and one or more speakers, as well as one or more sensors (e.g., a camera), for example, as described below. The illustrated real-world environment 100 includes a rectangular room 104A in which the user 110 is standing, and real objects 122A (a lamp), 124A (a table), 126A (a sofa), and 128A (a painting). The room 104A further includes a position coordinate 106 that may be considered as the origin of the real-world environment 100. As illustrated in FIG. 1A, an environment / world coordinate system 108 (including an x-axis 108X, a y-axis 108Y, and a z-axis 108Z) with its origin 106 (world coordinate) may define the coordinate space of the real-world environment 100. In some embodiments, the origin 106 of the environment / world coordinate system 108 may correspond to where the mixed reality system 112 was powered on. In some embodiments, the origin 106 of the environment / world coordinate system 108 may be reset during operation. In some examples, the user 110 may be considered a real object in the real environment 100. Similarly, the body parts (e.g., hands, feet) of the user 110 may be considered a real object in the real environment 100. In some examples, a user / listener / head coordinate system 114 (including an x-axis 114X, a y-axis 114Y, and a z-axis 114Z) with an origin at a point 115 (e.g., a user / listener / head coordinate) may define a coordinate space for the user / listener / head in which the mixed reality system 112 is located. An origin 115 of the user / listener / head coordinate system 114 may be defined with respect to one or more components of the mixed reality system 112. For example, the origin 115 of the user / listener / head coordinate system 114 may be defined relative to the display of the mixed reality system 112, such as during an initial calibration of the mixed reality system 112. A matrix (which may include translation and quaternion or other rotation matrices), or other suitable representation, may characterize the transformation between the user / listener / head coordinate system 114 space and the environment / world coordinate system 108 space.In some embodiments, the left ear coordinates 116 and right ear coordinates 117 may be defined relative to the origin 115 of the user / listener / head coordinate system 114. A matrix (which may include translation matrices and quaternion matrices or other rotation matrices), or other suitable representation, may characterize the transformation between the left ear coordinates 116 and right ear coordinates 117 and the user / listener / head coordinate system 114 space. The user / listener / head coordinate system 114 may simplify the representation of the position relative to the user's head or head-worn device, for example, relative to the environment / world coordinate system 108. Using simultaneous localization and mapping (SLAM), visual odometry, or other techniques, the transformation between the user coordinate system 114 and the environment coordinate system 108 may be determined and updated in real time.

[0035] 1B illustrates an exemplary virtual environment 130 corresponding to the real environment 100. The illustrated virtual environment 130 includes a virtual rectangular room 104B corresponding to the real rectangular room 104A, and virtual objects 122B, 124B, 126B corresponding to the real object 122A; virtual object 124B, 126B corresponding to the real object 126A. Metadata associated with the virtual objects 122B, 124B, 126B may include information derived from the corresponding real objects 122A, 124A, and 126A. The virtual environment 130 further includes a virtual monster 132 that does not correspond to any real object in the real environment 100. The real object 128A in the real environment 100 does not correspond to any virtual object in the virtual environment 130. A persistent coordinate system 133 (including an x-axis 133X, a y-axis 133Y, and a z-axis 133Z) with a point 134 as its origin (persistent coordinates) may define the coordinate space of the virtual content. The origin 134 of the persistent coordinate system 133 may be defined relative to one or more real objects, such as real object 126A. A matrix (which may include translation matrices and quaternion matrices or other rotation matrices), or other suitable representation, may characterize the transformation between the persistent coordinate system 133 space and the environment / world coordinate system 108 space. In some embodiments, each of the virtual objects 122B, 124B, 126B, and 132 may have its own persistent coordinate point relative to the origin 134 of the persistent coordinate system 133. In some embodiments, there may be multiple persistent coordinate systems, and each of the virtual objects 122B, 124B, 126B, and 132 may have its own persistent coordinate point relative to one or more persistent coordinate systems.

[0036] The persistent coordinate data may be coordinate data that is persistent with respect to the physical environment. The persistent coordinate data may be used by the MR system (e.g., MR system 112, 200) to position persistent virtual content, which may not be tied to the movement of the display on which the virtual object is displayed. For example, a two-dimensional screen may only display the virtual object relative to its position on the screen. As the two-dimensional screen moves, the virtual content may move with the screen. In some embodiments, the persistent virtual content may be displayed in a corner of a room. The MR user may look into the corner, see the virtual content, look out of the corner (where the virtual content may no longer be visible because the user's head movement may have moved the virtual content from within the user's field of view to a position outside the user's field of view), or look behind and see the virtual content in the corner (similar to how a real object may behave).

[0037] In some embodiments, the persistent coordinate data (e.g., persistent coordinate system and / or persistent coordinate frame) may include an origin and three axes. For example, the persistent coordinate system may be assigned by the MR system to the center of the room. In some embodiments, the user may move around the room, exit the room, and re-enter the room, and the persistent coordinate system may remain at the center of the room (e.g., because it persists relative to the physical environment). In some embodiments, virtual objects may be displayed using a transformation to the persistent coordinate data that may enable the display of persistent virtual content. In some embodiments, the MR system may use simultaneous localization and mapping to generate the persistent coordinate data (e.g., the MR system may assign a persistent coordinate system to a point in space). In some embodiments, the MR system may map the environment by generating persistent coordinate data at regular intervals (e.g., the MR system may assign a persistent coordinate system in a grid, and a persistent coordinate system may be within at least 5 feet of another persistent coordinate system).

[0038] In some embodiments, the persistent coordinate data may be generated by the MR system and transmitted to a remote server. In some embodiments, the remote server may be configured to receive the persistent coordinate data. In some embodiments, the remote server may be configured to synchronize persistent coordinate data from multiple observation instances. For example, multiple MR systems may map the same room with persistent coordinate data and transmit the data to a remote server. In some embodiments, the remote server may use this observation data to generate standard persistent coordinate data that may be based on one or more observations. In some embodiments, the standard persistent coordinate data may be more accurate and / or reliable than a single observation of the persistent coordinate data. In some embodiments, the standard persistent coordinate data may be transmitted to one or more MR systems. For example, an MR system may use image recognition and / or position data to recognize that it is located in a room that has corresponding standard persistent coordinate data (e.g., because other MR systems have previously mapped the room). In some embodiments, the MR system may receive standard persistent coordinate data corresponding to its location from the remote server.

[0039] 1A and 1B, the environment / world coordinate system 108 defines a shared coordinate space for both the real environment 100 and the virtual environment 130. In the illustrated example, the coordinate space has its origin at point 106. Furthermore, the coordinate space is defined by the same three orthogonal axes (108X, 108Y, 108Z). Thus, a first location in the real environment 100 and a second corresponding location in the virtual environment 130 can be described with respect to the same coordinate space. This simplifies the identification and display of corresponding locations in the real environment and the virtual environment, since the same coordinates can be used to identify both locations. However, in some examples, the corresponding real environment and virtual environment need not use a shared coordinate space. For example, in some examples (not shown), a matrix (which may include a translation matrix and a quaternion matrix or other rotation matrix), or other suitable representation, can characterize the transformation between the real environment coordinate space and the virtual environment coordinate space.

[0040] 1C illustrates an exemplary MRE 150 that simultaneously presents aspects of real environment 100 and virtual environment 130 to user 110 via mixed reality system 112. In the illustrated example, MRE 150 simultaneously presents real objects 122A, 124A, 126A, and 128A from real environment 100 (e.g., through a transparent portion of a display of mixed reality system 112) and virtual objects 122B, 124B, 126B, and 132 from virtual environment 130 (e.g., through an actively displayed portion of a display of mixed reality system 112) to user 110. As described above, origin 106 serves as the origin of a coordinate space corresponding to MRE 150, and coordinate system 108 defines the x-, y-, and z-axes of the coordinate space.

[0041] In the illustrated example, the mixed reality object includes corresponding pairs of real and virtual objects (i.e., 122A / 122B, 124A / 124B, 126A / 126B) that occupy corresponding positions in the coordinate space 108. In some examples, both real and virtual objects may be visible to the user 110 simultaneously. This may be desirable, for example, when a virtual object presents information designed to augment the view of the corresponding real object (such as in a museum application where a virtual object presents a missing piece of an old damaged sculpture). In some examples, a virtual object (122B, 124B, and / or 126B) may be displayed to occlude the corresponding real object (122A, 124A, and / or 126A) (e.g., via active pixelated occlusion using pixelated occlusion shutters). This may be desirable, for example, when a virtual object serves as a visual replacement for a corresponding real object (such as in an interactive storytelling application where inanimate real objects become "living" characters).

[0042] In some examples, a real object (e.g., 122A, 124A, 126A) may be associated with virtual content or helper data that may not necessarily constitute a virtual object. The virtual content or helper data may facilitate processing or handling of the virtual object in a mixed reality environment. For example, such virtual content may include a two-dimensional representation of the corresponding real object; a custom asset type associated with the corresponding real object; or statistical data associated with the corresponding real object. This information may enable or facilitate computations involving the real object without incurring unnecessary computational overhead.

[0043] In some examples, the presentations described above may also incorporate audio aspects. For example, in MRE 150, virtual monster 132 may be associated with one or more audio signals, such as footstep effects that are generated as the monster walks around MRE 150. As described further below, a processor in mixed reality system 112 may calculate an audio signal that corresponds to a mixed and processed combination of all such sounds within MRE 150 and present the audio signal to user 110 via one or more speakers included in mixed reality system 112 and / or one or more external speakers. Exemplary Mixed Reality System

[0044] An exemplary mixed reality system 112 may include a wearable head device (e.g., a wearable augmented reality or mixed reality head device) with a display (which may include left and right see-through displays, which may be near-eye displays, and associated components for coupling light from the displays to the user's eyes); left and right speakers (e.g., positioned adjacent the user's left and right ears, respectively); an inertial measurement unit (IMU) (e.g., mounted on the temple arms of a head device); a quadrature coil-type electromagnetic receiver (e.g., mounted on the left temple piece); left and right cameras (e.g., depth (time of flight) cameras) pointed away from the user; and left and right eye cameras pointed toward the user (e.g., for detecting the user's eye movements). However, the mixed reality system 112 may incorporate any suitable display technology, and any suitable sensors (e.g., optical, infrared, acoustic, LIDAR, EOG, GPS, magnetic). Additionally, the mixed reality system 112 may incorporate networking capabilities (e.g., Wi-Fi capabilities) for communicating with other devices and systems, including other mixed reality systems. The mixed reality system 112 may further include a battery (which may be attached to an auxiliary unit, such as a belt pack designed to be worn around the user's waist), a processor, and a memory. The wearable head device of the mixed reality system 112 may include a tracking component, such as an IMU or other suitable sensor, configured to output a set of coordinates of the wearable head device relative to the user's environment. In some examples, the tracking component may provide input to a processor that executes simultaneous localization and mapping (SLAM) and / or visual odometry algorithms. In some examples, the mixed reality system 112 may also include a handheld controller 300 and / or an auxiliary unit 320, which may be a wearable belt pack, as described further below.

[0045] 2A-2D show components of an exemplary mixed reality system 200 (which may correspond to the mixed reality system 112) that may be used to present an MRE (which may correspond to the MRE 150) or other virtual environment to a user. FIG. 2A shows a perspective view of a wearable head device 2102 included in the exemplary mixed reality system 200. FIG. 2B shows a top view of the wearable head device 2102 worn on a user's head 2202. FIG. 2C shows a front view of the wearable head device 2102. FIG. 2D shows an end view of an exemplary eyepiece 2110 of the wearable head device 2102. As shown in FIGS. 2A-2C, the exemplary wearable head device 2102 includes an exemplary left eyepiece (e.g., a left transparent waveguide set eyepiece) 2108 and an exemplary right eyepiece (e.g., a right transparent waveguide set eyepiece) 2110. Each eyepiece 2108 and 2110 can include a transmissive element through which the real environment can be seen, as well as a display element for presenting a display (e.g., via image-wise modulated light) that overlaps with the real environment. In some examples, such display elements can include surface diffractive optical elements for controlling the flow of image-wise modulated light. For example, the left eyepiece 2108 can include a left internal coupling grating set 2112, a left orthogonal pupil dilation (OPE) grating set 2120, and a left exit (output) pupil dilation (EPE) grating set 2122. As used herein, pupil may refer to the exit of light from an optical element such as a grating set or reflector. Similarly, the right eyepiece 2110 can include a right internal coupling grating set 2118, a right OPE grating set 2114, and a right EPE grating set 2116. The image-wise modulated light can be transmitted to the user's eye via the internal coupling gratings 2112 and 2118, the OPE 2114 and 2120, and the EPE 2116 and 2122. Each internal coupling grating set 2112, 2118 can be configured to deflect light towards its corresponding OPE grating set 2120, 2114.Each OPE grating set 2120, 2114 can be designed to gradually deflect light downward toward its associated EPE 2122, 2116, thereby extending the exit pupil formed horizontally. Each EPE 2122, 2116 can be configured to gradually redirect at least a portion of the light received from its corresponding OPE grating set 2120, 2114 toward a user's eyebox position (not shown) defined behind the eyepiece 2108, 2110, thereby extending the exit pupil formed at the eyebox vertically. Alternatively, instead of the internal coupling grating sets 2112 and 2118, the OPE grating sets 2114 and 2120, and the EPE grating sets 2116 and 2122, the eyepieces 2108 and 2110 can include other arrangements of gratings and / or refractive and reflective mechanisms to control the coupling of image-wise modulated light into the user's eye.

[0046] In some examples, the wearable head device 2102 can include a left temple arm 2130 and a right temple arm 2132, with the left temple arm 2130 including a left speaker 2134 and the right temple arm 2132 including a right speaker 2136. A quadrature coil electromagnetic receiver 2138 can be disposed in the left temple piece or another suitable location in the wearable head unit 2102. An inertial measurement unit (IMU) 2140 can be disposed in the right temple arm 2132 or another suitable location in the wearable head device 2102. The wearable head device 2102 can also include a left depth (e.g., time-of-flight) camera 2142 and a right depth camera 2144. The depth cameras 2142, 2144 can be suitably oriented in different directions to together cover a wider field of view.

[0047] In the example shown in Figures 2A-2D, a left source 2124 of image-wise modulated light can be optically coupled to the left eyepiece 2108 via a left internal coupling grating set 2112, and a right source 2126 of image-wise modulated light can be optically coupled to the right eyepiece 2110 via a right internal coupling grating set 2118. The sources 2124, 2126 of image-wise modulated light can include, for example, a fiber optic scanner; a projector including an electronic light modulator such as a digital light processing (DLP) chip or a liquid crystal on silicon (LCoS) modulator; or a light-emitting display such as a micro light-emitting diode (μLED) or micro organic light-emitting diode (μOLED) panel coupled to the internal coupling grating set 2112, 2118 using one or more lenses per side. The input coupling grating set 2112, 2118 can deflect light from the sources 2124, 2126 of image-wise modulated light to an angle that exceeds the critical angle of total internal reflection (TIR) ​​of the eyepiece 2108, 2110. The OPE grating sets 2114, 2120 gradually deflect the light propagating by TIR downwards towards the EPE grating sets 2116, 2122. The EPE grating sets 2116, 2122 gradually couple the light towards the user's face, including the pupils of the user's eyes.

[0048] In some examples, as shown in FIG. 2D, each of the left eyepiece 2108 and the right eyepiece 2110 includes multiple waveguides 2402. For example, each eyepiece 2108, 2110 can include multiple individual waveguides, each dedicated to a respective color channel (e.g., red, blue, and green). In some examples, each eyepiece 2108, 2110 can include multiple sets of such waveguides, each set configured to impart a different wavefront curvature to the emitted light. The wavefront curvature may be convex with respect to the user's eye, for example, to present a virtual object located at a distance in front of the user (e.g., a distance corresponding to the inverse of the wavefront curvature). In some examples, the EPE grating sets 2116, 2122 can include curved grating grooves that achieve a convex wavefront curvature by modifying the pointing vector of the emitted light across each EPE.

[0049] In some examples, stereoscopically calibrated left and right eye images can be presented to the user through the image-wise light modulators 2124, 2126 and eyepieces 2108, 2110 to create the perception that the displayed content is three-dimensional. By selecting a waveguide (and thus corresponding wavefront curvature) such that the virtual object is displayed at a distance close to that shown by the stereoscopic left and right images, the perceived realism of the presentation of the three-dimensional virtual object can be enhanced. This technique can also reduce sickness experienced by some users, which may be caused by differences between the depth perception cues provided by the stereoscopic left and right eye images and the autonomic regulation of the human eye (e.g., focus dependent on object distance).

[0050] FIG. 2D shows an end view from above of the right eyepiece 2110 of the exemplary wearable head device 2102. As shown in FIG. 2D, the plurality of waveguides 2402 can include a first subset of three waveguides 2404 and a second subset of three waveguides 2406. The two subsets of waveguides 2404, 2406 can be distinguished by different EPE gratings featuring different grating line curvatures to impart different wavefront curvatures to the exiting light. Within each subset of waveguides 2404, 2406, each waveguide can be used to couple a different spectral channel (e.g., one of the red, green, and blue spectral channels) to the user's right eye 2206. (Although not shown in FIG. 2D, the structure of the left eyepiece 2108 is similar to that of the right eyepiece 2110.)

[0051] FIG. 3A illustrates an exemplary handheld controller component 300 of the mixed reality system 200. In some examples, the handheld controller 300 includes a grip portion 346 and one or more buttons 350 disposed along a top surface 348. In some examples, the buttons 350 may be configured for use as optical tracking targets, for example, to track six degrees of freedom (6DOF) movement of the handheld controller 300 in conjunction with a camera or other optical sensor, which may be mounted on a head unit (e.g., the wearable head device 2102) of the mixed reality system 200. In some examples, the handheld controller 300 includes a tracking component (e.g., an IMU or other suitable sensor) for detecting a position or orientation, such as a position or orientation relative to the wearable head device 2102. In some examples, such a tracking component may be disposed within a handle of the handheld controller 300 and / or may be mechanically coupled to the handheld controller. The handheld controller 300 can be configured to provide one or more output signals corresponding to one or more of: a button press state; or a position, orientation, and / or movement of the handheld controller 300 (e.g., via an IMU). Such output signals may be used as inputs to a processor of the mixed reality system 200. Such inputs may correspond to the position, orientation, and / or movement of the handheld controller (and, by extension, to the position, orientation, and / or movement of a user's hand holding the controller). Such inputs may also correspond to a user pressing a button 350.

[0052] 3B illustrates an exemplary auxiliary unit 320 of the mixed reality system 200. The auxiliary unit 320 may include a battery for providing energy to operate the system 200 and may include a processor for executing programs for operating the system 200. As shown, the exemplary auxiliary unit 320 includes a clip 2128 for attaching the auxiliary unit 320 to a user's belt, or the like. Other form factors are suitable for the auxiliary unit 320 and will be apparent, including form factors that do not involve attaching the unit to a user's belt. In some examples, the auxiliary unit 320 is coupled to the wearable head device 2102 via a multi-conduit cable, which may include, for example, electrical wires and optical fibers. A wireless connection between the auxiliary unit 320 and the wearable head device 2102 may also be used.

[0053] In some examples, the mixed reality system 200 may include one or more microphones for detecting sounds and providing corresponding signals to the mixed reality system. In some examples, the microphones may be attached to or integrated with the wearable head device 2102 and may be configured to detect the user's voice. In some examples, the microphones may be attached to or integrated with the handheld controller 300 and / or the auxiliary unit 320. Such microphones may be configured to detect environmental sounds, ambient noise, the user's or a third party's voice, or other sounds.

[0054] FIG. 4 illustrates an example functional block diagram that may correspond to an example mixed reality system, such as the mixed reality system 200 described above (which may correspond to the mixed reality system 112 with respect to FIG. 1). As shown in FIG. 4, an example handheld controller 400B (which may correspond to the handheld controller 300 ("totem")) includes a totem-to-wearable head device six degrees of freedom (6DOF) totem subsystem 404A, and an example wearable head device 400A (which may correspond to the wearable head device 2102) includes a totem-to-wearable head device 6DOF subsystem 404B. In this example, the 6DOF totem subsystem 404A and the 6DOF subsystem 404B cooperate to determine six coordinates (e.g., three translational offsets and rotations along three axes) of the handheld controller 400B relative to the wearable head device 400A. The six degrees of freedom may be expressed relative to the coordinate system of the wearable head device 400A. The three translational offsets may be represented as X, Y, and Z offsets in such a coordinate system, as a translation matrix, or some other representation. The rotational degrees of freedom may be represented as a sequence of yaw, pitch, and roll rotations, as a rotation matrix, as a quaternion, or some other representation. In some examples, the wearable head device 400A; one or more depth cameras 444 (and / or one or more non-depth cameras) included in the wearable head device 400A; and / or one or more optical targets (e.g., the buttons 350 of the handheld controller 400B described above, or a dedicated optical target included in the handheld controller 400B) may be used for 6DOF tracking. In some examples, the handheld controller 400B may include a camera, as described above, and the wearable head device 400A may include an optical target for optical tracking in conjunction with the camera. In some examples, the wearable head device 400A and the handheld controller 400B each include a set of three orthogonally oriented solenoids used to wirelessly transmit and receive three identifiable signals.By measuring the relative magnitudes of the three distinguishable signals received at each of the coils used for receiving, the 6DOF of the wearable head device 400A relative to the handheld controller 400B can be determined. Additionally, the 6DOF totem subsystem 404A can include an inertial measurement unit (IMU) useful for providing improved accuracy and / or more timely information regarding rapid movements of the handheld controller 400B.

[0055] In some embodiments, the wearable system 400 can include a microphone array 407 that can include one or more microphones disposed on the headgear device 400A. In some embodiments, the microphone array 407 can include four microphones. Two microphones can be disposed on the front of the headgear 400A and two microphones can be disposed on the back of the headgear 400A (e.g., one on the left rear and one on the right rear). In some embodiments, the signals received by the microphone array 407 can be transmitted to the DSP 408. The DSP 408 can be configured to perform signal processing on the signals received from the microphone array 407. For example, the DSP 408 can be configured to perform noise reduction, acoustic echo cancellation, and / or beamforming on the signals received from the microphone array 407. The DSP 408 can be configured to transmit the signals to the processor 416.

[0056] In some examples, it may be necessary to transform coordinates from a local coordinate space (e.g., a coordinate space fixed with respect to the wearable head device 400A) to an inertial coordinate space (e.g., a coordinate space fixed with respect to the real environment), e.g., to compensate for movement of the wearable head device 400A with respect to the coordinate system 108. For example, such a transformation may be necessary for the display of the wearable head device 400A to present the virtual object at an expected position (e.g., the same position in the bottom right corner of the display) and orientation with respect to the real environment, rather than at a fixed position and orientation on the display, in order to maintain the illusion that the virtual object (e.g., a virtual person sitting in a real chair and facing forward regardless of the position and orientation of the wearable head device) is present in the real environment (and does not appear unnaturally placed in the real environment, e.g., as the wearable head device 400A moves and rotates). In some examples, the compensatory transformation between coordinate spaces can be determined by processing images from the depth camera 444 using SLAM and / or visual odometry procedures to determine the transformation of the wearable head device 400A with respect to the coordinate system 108. In the example shown in FIG. 4, the depth camera 444 can be coupled to the SLAM / visual odometry block 406 and can provide images to the block 406. An implementation of the SLAM / visual odometry block 406 can include a processor configured to process this image and determine the position and orientation of the user's head, which can be used to identify a transformation between the head coordinate space and another coordinate space (e.g., an inertial coordinate space). Similarly, in some examples, an additional source of information regarding the user's head pose and position is obtained from the IMU 409. Information from the IMU 409 can be integrated with information from the SLAM / visual odometry block 406 to provide improved accuracy and / or more timely information regarding rapid adjustments to the user's head pose and position.

[0057] In some examples, the depth camera 444 can provide 3D images to a hand gesture tracker 411, which can be implemented in a processor of the wearable head device 400A. The hand gesture tracker 411 can identify the user's hand gestures, for example, by matching the 3D images received from the depth camera 444 with stored patterns representing the hand gestures. Other suitable techniques for identifying the user's hand gestures will be apparent.

[0058] In some examples, the one or more processors 416 may be configured to receive data from the 6DOF headgear subsystem 404B, the IMU 409, the SLAM / visual odometry block 406, the depth camera 444, and / or the hand gesture tracker 411 of the wearable head device. The processor 416 may also send and receive control signals from the 6DOF totem system 404A. The processor 416 may be wirelessly coupled to the 6DOF totem system 404A, such as in examples where the handheld controller 400B is not connected. The processor 416 may further communicate with additional components, such as an audiovisual content memory 418, a graphical processing unit (GPU) 420, and / or a digital signal processor (DSP) audio spatializer 422. The DSP audio spatializer 422 may be coupled to a head-related transfer function (HRTF) memory 425. The GPU 420 may include a left channel output coupled to a left light source 424 of image-wise modulated light and a right channel output coupled to a right light source 426 of image-wise modulated light. The GPU 420 may output stereoscopic image data to the light sources 424, 426 of image-wise modulated light, for example, as described above with reference to FIGS. 2A-2D. The DSP audio spatializer 422 may output audio to the left speaker 412 and / or the right speaker 414. The DSP audio spatializer 422 may receive an input from the processor 419 indicating a direction vector from the user to a virtual sound source (which may be moved by the user, for example, via the handheld controller 320). Based on the direction vector, the DSP audio spatializer 422 may determine a corresponding HRTF (e.g., by accessing an HRTF or by interpolating multiple HRTFs). The DSP audio spatializer 422 may then apply the determined HRTF to an audio signal, such as an audio signal corresponding to a virtual sound generated by a virtual object.This can increase the realism and presence of virtual sounds by incorporating the user's relative position and orientation to the virtual sounds in a mixed reality environment, i.e., by presenting virtual sounds that match the user's expectations of how the virtual sounds would sound if they were real sounds in a real environment.

[0059] 4, one or more of the processor 416, GPU 420, DSP audio spatializer 422, HRTF memory 425, and audiovisual content memory 418 may be included in an auxiliary unit 400C (which may correspond to auxiliary unit 320 described above). The auxiliary unit 400C may include a battery 427 for powering its components and / or for powering the wearable head device 400A or the handheld controller 400B. Including such components in an auxiliary unit that may be worn on the user's waist can limit the size and weight of the wearable head device 400A, which in turn can reduce fatigue on the user's head and neck.

[0060] 4 illustrates elements corresponding to various components of an exemplary mixed reality system, various other suitable arrangements of these components will be apparent to those skilled in the art. For example, elements illustrated in FIG. 4 as being associated with the auxiliary unit 400C can instead be associated with the wearable head device 400A or the handheld controller 400B. Furthermore, some mixed reality systems may dispense with the handheld controller 400B or the auxiliary unit 400C entirely. Such variations and modifications should be understood to fall within the scope of the disclosed examples. Acoustic Waveguide

[0061] Because XR systems (e.g., MR systems 112, 200) mix real content with virtual content, true immersion may depend on engaging as many of the user's senses as possible. In some instances, creating realistic sound may include subtleties that are difficult to replicate with audio signal processing. For example, in real environments, sound is generally received by an individual's ear via a frontal incidence wavefront. The frontal incidence wavefront may interact with the individual's pinna, the outer part of the ear that is physically visible, which may impart a unique acoustic signature to the external sound the individual hears. If a sound source, e.g., a speaker, is mounted near the entrance of the user's ear canal in an above-the-ear or intra-auricular configuration, as is typical in XR headsets, the sound received by the user may not include the unique acoustic signature of the user's pinna, potentially compromising the user's immersive XR experience.

[0062] Furthermore, placing the speaker's sound transducer close to the user's ear may add bulk and weight to the head mounted display's arm, which may be uncomfortable when the user's ear supports the weight. Furthermore, some speaker systems are prone to sound leakage, where the sound generated by the speaker may be heard by other individuals in the vicinity. Sound leakage is not only annoying to the user and other individuals, but may also interfere with the user's audio privacy. Therefore, it may be desirable to provide a sound system that can provide an acoustic input that includes the acoustic signature of the user's pinna with minimal sound leakage.

[0063] The embodiments of the present disclosure relate to an acoustic waveguide and a method of use for presenting an audio signal. The acoustic waveguide according to the embodiments of the present disclosure can provide a frontal sound incidence to a user such that the sound perceived by the user can include the acoustic signature of the user's pinna. The embodiments of the present disclosure can also provide minimal sound leakage due to the sound source directivity of the acoustic waveguide. The device according to the embodiments of the present disclosure can include a waveguide member comprising a hollow body having a first end and a second end. The device can further include a sound source disposed at the first end of the waveguide configured to emit at least a first sound wave. The device can further include a plurality of acoustic vents disposed at a lower surface of the body of the waveguide, each of the plurality of acoustic vents configured to receive the first sound wave and further configured to emit a respective sound wave based on the first sound wave, each sound wave corresponding to a respective point sound source.

[0064] An embodiment of the present disclosure may include a head-wearable device. For example, the head-wearable device may include a front frame, a display coupled to the front frame, an arm coupled to the front frame and configured to attach the head-wearable device to a user's head, and an acoustic waveguide. In one or more examples, the acoustic waveguide may include a waveguide member having a hollow body having a first end and a second end, an acoustic source disposed at the first end of the waveguide, and a plurality of acoustic vents disposed on a lower surface of the body of the waveguide, each of the plurality of acoustic vents configured to receive a first acoustic wave and further to emit a respective acoustic wave based on the first acoustic wave, each acoustic wave corresponding to a respective point sound source.

[0065] An embodiment of the present disclosure may include a method for presenting an audio signal. According to one or more embodiments, the method may include emitting one or more acoustic waves of the audio signal via an audio source into a waveguide member of an acoustic waveguide, receiving the one or more acoustic waves at a first acoustic vent, the first acoustic vent being disposed on a lower surface of the waveguide member, generating a first point sound source at the first acoustic vent based on the one or more acoustic waves, receiving the one or more acoustic waves at a second acoustic vent, the second acoustic vent being disposed on a lower surface of the waveguide member, generating a second point sound source at the second acoustic vent based on the one or more acoustic waves, and presenting the first point sound source and the second point sound source.

[0066] 5A illustrates an exemplary acoustic waveguide 500A in accordance with one or more embodiments of the present disclosure. In some embodiments, the acoustic waveguide can be integrated into a wearable head device, as described in more detail below. The acoustic waveguide 500A in accordance with an embodiment of the present disclosure can include one or more sound sources 502, a waveguide 504, a sound absorber 506, and one or more acoustic vents 508a-d.

[0067] The waveguide 504 may correspond to a hollow body having a first end 512 and a second end 514. In some embodiments, the first end 512 may include an opening that provides access to the interior of the hollow body. In some embodiments, the first end 512 may be closed. In some embodiments, the second end 514 may be closed. In such embodiments, the second end may include a back surface 510 that covers the opening of the second end 514. The waveguide 504 may further include a top surface region 516 and a bottom surface region 518.

[0068] As shown, the waveguide 504 can correspond to a cylindrical, e.g., tubular, hollow body having a circular cross-section. However, one skilled in the art will appreciate that the shape of the waveguide 504 is not intended to limit the scope of the present disclosure. For example, the waveguide 504 can include a cross-section having an elliptical, triangular, rectangular, diamond, trapezoidal, and / or irregular shape. In some embodiments, the cross-section of the waveguide 504 can vary along the length of the waveguide, such that, for example, the area of ​​a cross-section of the waveguide taken near the first end 512 can correspond to a first cross-sectional shape and / or a first area, while the area of ​​a cross-section of the waveguide taken near the second end 514 can correspond to a second cross-sectional shape and / or a second area that is different from the first cross-sectional shape and / or first area.

[0069] In some embodiments, the diameter and / or cross-sectional area of ​​the waveguide 504 can be adjusted to ensure that certain audio frequencies, e.g., higher frequencies, such as 50 Hz to 150 Hz, 50 Hz to 250 Hz, 200 Hz to 500 Hz, 400 Hz to 1 kHz, etc., can be propagated longitudinally along the length of the tube. For example, in one or more embodiments, a narrower diameter, e.g., smaller cross-sectional area, can facilitate the propagation of one or more acoustic waves as longitudinal waves. This can aid in the propagation of higher audio frequencies. Additionally, the propagation of one or more acoustic waves as longitudinal waves can ensure that a time delay between one or more acoustic waves exiting adjacent vents, e.g., first acoustic vent 508a and second acoustic vent 508b, corresponds to the time it takes for the one or more acoustic waves to travel between the adjacent vents. In one or more examples, the diameter and / or cross-sectional area can be adjusted by running one or more simulations of the acoustic waveguide. For example, the first acoustic vent 508A may be approximately 200% of the cross-sectional volume of the second vent 508B, 400% of the cross-sectional volume of the third vent 508C, and 800% of the cross-sectional volume of the fourth vent 508D. In some examples, the following formula may be used to determine the geometry of the acoustic vents: [ka] In the formula, L v is the length of the vent, and D v is the inside diameter of the vent, and V b is the internal air volume of the enclosure, and F b is the tuning frequency of the enclosure, K is the end correction, and N v is the number of vents.

[0070] In some embodiments, the sound source 502 can be located at a first end 512 of the waveguide 504. As shown, the sound source 502 can be located outside the waveguide 504, with the sound source 502 configured to emit sound waves into an opening of the first end 512 of the waveguide 504. In some embodiments, the sound source 502 can be located inside the waveguide 504. In such embodiments, the first end 512 of the waveguide can be open or closed. In one or more examples, the diameter of the sound source 502 can correspond to the diameter of the tube. The sound source 502 can be configured to emit sound waves that can be heard by an individual. For example, the sound source can receive one or more signals corresponding to audio content. In some examples, the sound source 502 can be in communication with an audio spatializer, such as the DSP audio spatializer 422, to output audio signals. In some embodiments, the sound source 502 can be a speaker and / or an audio transducer.

[0071] The sound absorber 506 can be disposed at the second end 514 of the waveguide 504. The sound absorber 506 can be configured to absorb sound in the waveguide 504 emitted by the sound source 502. In this manner, the sound absorber 506 can reduce resonance of sound waves emitted by the sound source 502 in the waveguide 504. As shown, the sound absorber 506 can be disposed in the waveguide 504 at the second end 514. In some embodiments, the sound absorber 506 can occupy an area of ​​the second end 514 such that the back surface 510 of the waveguide 504 is covered. In some embodiments, there may be a gap between the sound absorber 506 and the inner surface of the waveguide such that the sound absorber 506 does not completely cover the back surface 510 of the waveguide 504. In one or more embodiments, the sound absorber 506 can be formed from a sound absorbing material. In one or more embodiments, sound absorbing materials can include, for example, but are not limited to, acoustic woven panels, wadding, mineral wool, fiberglass, partially reticulated plastic foams, fully reticulated plastic foams with higher absorption coefficients, multi-layer composite materials, and the like.

[0072] As shown in the figure, the waveguide 504 can include one or more acoustic vents 508a-508d. In some embodiments, the acoustic vents 508a-508d can be disposed on a lower surface region 518 of the waveguide 504. The acoustic vents 508a-508d can be configured to each emit sound emitted by the sound source 502. In this manner, the acoustic vents 508a-508d can be configured to emit sound as separate point sources based on the output of a single sound source, for example, the sound source 502. Although the figure shows four acoustic vents, one skilled in the art will understand that the acoustic waveguide 500A according to an embodiment of the present disclosure can include more or fewer acoustic vents.

[0073] FIG. 5B illustrates an exemplary acoustic waveguide 500B according to one or more embodiments of the present disclosure. As shown, the acoustic waveguide 500B can be substantially similar to the acoustic waveguide 500A. For example, the acoustic waveguide 500B can include one or more sound sources 502, a waveguide 504, a sound absorber 506, and one or more acoustic vents 528a-528d. As shown, one or more acoustic vents 528a-528d. In some embodiments, the one or more acoustic vents can include an acoustic mesh disposed therein, for example across the opening of the acoustic vent. For example, the acoustic mesh can include a micro acoustic mesh having at least one selected from a twill weave pattern or a plain weave pattern. In some embodiments, the acoustic mesh can have an inverted plain weave pattern or a multi-twill weave having 2-5 bonded fibers or wires. In some embodiments, the density of the acoustic mesh can vary. In some embodiments, the acoustic mesh can have the properties of a monofilament material. In some embodiments, the acoustic mesh can include a micro-acoustic mesh having at least one selected from polyester characteristics, polyimide characteristics, polypropylene characteristics, polyamide characteristics, nylon characteristics, and / or meta-aramid characteristics.

[0074] In one or more examples, the distance between the sound source 502 and the first acoustic vent 508a can be adjusted so that lower frequency sound waves radiate minimal energy through the acoustic vent 508a. In one or more examples, the distance between the acoustic vents 508a-508d and / or the diameter of the waveguide 504 can be adjusted so that the delay time between each of the acoustic vents 508a-508d corresponds to the time it takes for an acoustic wave emitted by the sound source 502 to travel within the waveguide 504. For example, the waveguide 504 can be adjusted so that longitudinal waves propagate within the body of the waveguide. In some examples, one or more sound waves emitted from the acoustic vents 508a-508d can provide improved focusing directionality of the sound, such as by beamforming the waves and / or modifying the speed of the waves using acoustic meshes of various weave shapes, weave diameters and materials, such that sound leakage is reduced.

[0075] 6A-6C illustrate examples of acoustic waveguides, such as acoustic waveguides 500A, 500B, disposed within a wearable head device (e.g., wearable head device 2102 of mixed reality system 200) according to embodiments of the present disclosure. As shown, the wearable head device can include a frame including a front frame 632A coupled to a temple portion 634A. The front frame 632A can be configured to rest on a user's nose, and the temple portion 634A can correspond to an arm of the wearable head device that can be configured to rest on a user's ear. In one or more examples, the illustrated acoustic waveguides 600A-600C can correspond to acoustic waveguide 500A described above.

[0076] FIG. 6A illustrates an acoustic waveguide 600A disposed within a wearable head device according to an embodiment of the present disclosure. As shown, the acoustic waveguide 600A can include a sound source 602A, a waveguide 604A, a sound absorber 606A, and one or more acoustic vents 608a-608d. In one or more examples, the acoustic waveguide 600A can correspond to the acoustic waveguide 500A described above. In some embodiments, the sound source 602A can be attached and / or disposed on the front frame 632A of the wearable head device. In this manner, the weight of the sound source can be distributed to the bridge of the nose, allowing for a more comfortable weight distribution for the user. This also allows the temple portion 634A to be thinner and lighter than the temple portion supporting the sound source, e.g., the right temple arm 2132 supporting the right speaker 2136. As shown, the waveguide 604A can be disposed within the temple portion 634, e.g., the arm, of the head wearable device. In some embodiments, the hollow body of the waveguide 604A can be disposed within the temple portion 634A. In some embodiments, the hollow body of the waveguide 604A can be integrally formed with the temple portion 634A such that the outer surface of the waveguide 604A corresponds to a surface of the temple portion 634A.

[0077] FIG. 6B illustrates an acoustic waveguide 600B disposed within a wearable head device according to an embodiment of the present disclosure. As shown, the acoustic waveguide 600A can include a sound source 602B, a waveguide 604B, a sound absorber 606B, and one or more acoustic vents 608a-608d. In one or more examples, the acoustic waveguide 600B can correspond to the acoustic waveguide 500A described above. In some embodiments, the sound source 602B can be attached and / or disposed on the front frame 632B of the wearable head device. In this manner, the weight of the sound source can be distributed to the bridge of the nose, allowing for a more comfortable weight distribution for the user. This also allows the temple portion 634B to be thinner and lighter than the temple portion supporting the sound source, e.g., the right temple arm 2132 supporting the right speaker 2136. As shown, the waveguide 604B can be disposed within the temple portion 634B, e.g., the arm, of the head wearable device. For example, the hollow body of waveguide 604B can be disposed within temple portion 634B. In some embodiments, the hollow body of waveguide 604B can be integrally formed with temple portion 634B such that one or more outer surfaces of waveguide 604B correspond to one or more outer surfaces of temple portion 634B. For example, as shown in the figure, a lower surface of waveguide 604B can correspond to a lower surface of temple portion 834B.

[0078] FIG. 6C illustrates an acoustic waveguide 600C disposed within a wearable head device according to an embodiment of the present disclosure. As shown, the acoustic waveguide 600C can include a sound source 602C, a waveguide 604C, a sound absorber 606C, and one or more acoustic vents 608a-608d. In one or more examples, the acoustic waveguide 600C can correspond to the acoustic waveguide 500A described above. In some embodiments, the sound source 602C can be attached and / or disposed on the front frame 632C of the wearable head device. In this manner, the weight of the sound source can be distributed to the bridge of the nose, allowing for a more comfortable weight distribution for the user. This also allows for a thinner and lighter temple portion 634C. As shown, the waveguide 604C can be attached to the temple portion 634C of the head wearable device, for example, on the underside of the arm, for example, on the underside. In some embodiments, the hollow body of the waveguide 604C can be integrally formed with the temple portion 634C such that one or more outer surfaces of the waveguide 604C correspond to one or more outer surfaces of the temple portion 634C.

[0079] FIG. 6D illustrates an acoustic waveguide 600D disposed within a wearable head device according to an embodiment of the present disclosure. As shown, the acoustic waveguide 600D can include an acoustic source 602D, a waveguide 604D, a sound absorber 606D, and one or more acoustic vents 648A-648D. In one or more examples, the acoustic waveguide 6003 can generally correspond to the acoustic waveguide 500D described above. As shown in FIG. 6D, the vents 648A-648D can be located on the temple side and can be positioned to provide sound waves in an inward direction, for example, toward the head of a user wearing the device. In some embodiments, the vents can be angled downward and / or in a direction toward the ear, for example, at a 45° angle toward the ear (although other angles may be used). Thus, the configuration and / or angle of the vents are not intended to limit the scope of the present disclosure. In some examples, the angle of the arrangement of the vents can affect the propagation direction of the sound waves. For example, the configuration of acoustic vents 648A-648D can create a dipole having an angle corresponding to line M N. In some embodiments, mesh impedance can further affect the propagation direction.

[0080] 7 illustrates an example flow chart of a process 700 for operating an acoustic waveguide in accordance with an embodiment of the present disclosure. In one or more examples, steps illustrated in process 700 can be combined, modified, and / or omitted as desired. Although portions of process 700 may be described with respect to one or more components of acoustic waveguide 600A, one of ordinary skill in the art will understand that process 700 can be applied to one or more of the acoustic waveguides disclosed herein.

[0081] In step 702, an acoustic waveguide source, e.g., sound source 602A, can emit one or more acoustic waves, e.g., acoustic wave 624, corresponding to an audio signal at a first end of acoustic waveguide 600A. In one or more examples, the audio signal can correspond to one or more sounds associated with an XR environment. In some embodiments, the audio signal can be generated and / or output continuously while a user is using the XR system (e.g., XR system 200). In some embodiments, the audio signal can be received from an audio spatializer, e.g., DSP audio spatializer 422. In some examples, the one or more acoustic waves 624 can propagate longitudinally along a length of waveguide 604A. In one or more examples, the diameter and / or cross-section of waveguide 604A can be adjusted such that audio frequencies propagate longitudinally. In some embodiments, the one or more acoustic waves can range in frequency from 50 Hz to 5000 Hz.

[0082] In step 704, the acoustic waveguide can receive one or more acoustic waves at the first acoustic vent. For example, the acoustic waveguide 600A can receive one or more acoustic waves at the first acoustic vent 608a at a first time. In step 706, the acoustic waveguide can generate a first sound source, which radiates from the first acoustic vent. For example, the acoustic waveguide 600A can generate a first sound source 626a, which radiates from the first acoustic vent 608a. In one or more examples, the distance between the sound source 606A and the first acoustic vent 608a can be adjusted so that undesired frequencies, e.g., lower frequency evanescent waves, are not included in the first sound source.

[0083] In step 708, the acoustic waveguide can receive one or more acoustic waves at the second acoustic vent (e.g., after one or more acoustic waves are received at the first acoustic vent). For example, acoustic waveguide 600A can receive one or more acoustic waves at the second acoustic vent 608b at a second time. In step 710, the acoustic waveguide can generate a second sound source, which radiates from the second acoustic vent. For example, acoustic waveguide 600A can generate a second sound source 626b, which radiates from the second acoustic vent 608b. In one or more examples, the distance between the first acoustic vent 608a and the second acoustic vent 608b and / or the diameter of the waveguide 604a can be adjusted such that the difference between the first time and the second time corresponds to the time it takes for one or more acoustic waves 624 to travel between the first acoustic vent 608a and the second acoustic vent 608b.

[0084] In step 712, the acoustic waveguide can present a first sound source and a second sound source. For example, as shown, the acoustic waveguide 600A can present at least a first sound source 626a and a second sound source 626b to the user's ear 630. For example, the user may be wearing a head wearable device including the acoustic waveguide 600A. In one or more examples, the first sound source 626a and the second sound source 626b can form an acoustic wavefront 628 that can be received as a frontal wavefront at the user's ear 630. In this manner, the first sound source 626a and the second sound source 626b can provide a frontal sound incidence to the user's ear such that the acoustic signature of the user's pinna is included in the sound heard by the user. In this manner, embodiments of the present disclosure can vary the wave speed with acoustic meshes of various weave shapes, weave diameters, and materials, allowing the present invention to modify the phase of the focused wavefront radiated to the user's ear. This focused acoustic wave can improve the efficiency of the process and reduce energy leakage from the ear.

[0085] In one or more embodiments, the one or more acoustic waves 624 can be absorbed by an acoustic absorber 606A disposed at the second end of the waveguide 604A. In this manner, resonance of the one or more acoustic waves 624 within the waveguide 604A can be reduced.

[0086] FIG. 7B illustrates an exemplary acoustic radiation pattern showing sound propagation from an acoustic waveguide according to an embodiment of the present disclosure. The acoustic radiation pattern illustrates how sound from an acoustic waveguide can travel through space. The vent orientation arrangement can determine the propagation angle and / or polar directivity of the acoustic wave. In some embodiments, the mesh impedance can also affect the phasing of the acoustic wave propagation. As shown, sound radiated from the acoustic waveguide can propagate in a dipole directional polar pattern 728. As shown, sound is directed in a direction m toward the user's ear 730 and in an opposite direction n, where sound propagating in direction m can have a larger amplitude than sound propagating in direction n. As shown, direction m can be directed downward from the lower surface of the acoustic waveguide toward the user's head and / or ear, and direction n can be directed upward away from the user's ear 730.

[0087] FIG. 7C is a diagram illustrating an example acoustic radiation pattern showing sound propagation from an acoustic waveguide according to an embodiment of the present disclosure. The acoustic radiation pattern illustrates how sound from an acoustic waveguide can travel through space. As shown, sound radiated from an acoustic waveguide can propagate in a dipole directional polar pattern 728. As shown, sound is directed in a direction m toward a user's ear 730 and in an opposite direction n. Similar to FIG. 7B, direction m may be directed downward from the lower surface of the acoustic waveguide toward the user's head and / or ear, and direction n may be directed upward away from the user's ear 730, where sound propagating in direction m may have a larger amplitude than sound propagating in direction n. In some examples, the directional polar pattern can correspond to other shapes, such as, but not limited to, cardioid, high cardioid, and irregular shapes for specific applications.

[0088] FIG. 7D shows an example sound radiation pattern showing the amplitude of sound in different directions. For example, FIG. 7D can correspond to the cross-sectional view of FIG. 7C. As shown, the sound propagated by the acoustic waveguide has a maximum amplitude in the forward and backward directions, with 0° corresponding to a direction m, e.g., toward the ear, and 180° corresponding to a direction m, e.g., away from the ear. The amplitude is smallest in lateral directions, e.g., 90° and 270°, from the acoustic waveguide. In this manner, the acoustic waveguide according to the embodiment of the present disclosure can reduce sound leakage in lateral directions away from the user's head.

[0089] For example, briefly referring to FIG. 12, an exemplary wearable head device 1202 having a speaker 1204 is shown. As shown, the speaker 1204 may be located on an arm of the wearable head device and pointed towards the user's head. The speaker may emit acoustic waves in a direction O towards the user's temple. The acoustic waves may reflect from the user's temple such that a first portion of the reflected acoustic wave 1208 travels towards the user's ear while a second portion of the acoustic wave 1206 travels laterally, e.g., propagates into the user's environment. Such sound leakage may lead to user privacy concerns and / or may be an annoyance to individuals who can hear the sound from the speaker 1204 within the user's environment.

[0090] FIG. 8 illustrates an acoustic waveguide 800 disposed within a wearable head device according to an embodiment of the present disclosure. As shown, the acoustic waveguide 800 can include an acoustic source 802, a waveguide manifold 804, and one or more acoustic vents 808a-d. In some embodiments, the acoustic vents 808a-d can include an acoustic mesh as described above with respect to the acoustic vents 528a-d. As shown, the acoustic source 802 can be disposed on a front frame 832 of the wearable head device. In this manner, the weight of the acoustic source can be distributed to the bridge of the nose, allowing for a more comfortable weight distribution for the user. This also allows the temple portion 834 to be thinner and lighter than the temple portion supporting the audio source, for example, the right temple arm 2132 supporting the right speaker 2136. In some examples, the audio source 802 can be disposed on the temple portion 834.

[0091] As shown, the waveguide manifold 804 can be disposed in a temple portion 834, e.g., an arm, of the head wearable device. As shown, the waveguide 804 can correspond to an acoustic manifold. In one or more examples, the waveguide manifold 804 can include an inlet 812 at a first end of the waveguide manifold 804, a manifold body 844, and one or more branches 848a-d, each branch corresponding to an acoustic vent 808a-d. As shown, the waveguide manifold 804 can receive one or more sound waves 824 generated by the sound source 802. The one or more sound waves 824 can propagate longitudinally within the body 844 of the waveguide manifold 804. As one or more acoustic waves 824 approach one or more branches 848a-d, the one or more acoustic waves can propagate through each of the corresponding branches 848a-d and exit the waveguide manifold 804 via a respective acoustic vent 808a-d. In one or more examples, the acoustic waveguide 800 can be operated according to the process 700.

[0092] In some embodiments, the distance between the inlet 812 and each acoustic vent 808a-808d can determine the timing of one or more acoustic waves emanating from a particular acoustic vent. In some examples, the distance between the inlet 812 and each acoustic vent 808a-808d can be adjusted such that the time delay between one or more acoustic waves emanating from adjacent vents, e.g., between the first acoustic vent 808a and the second acoustic vent 808b, corresponds to the time difference between the time it takes for one or more acoustic waves 624 to travel between the inlet and each of the adjacent vents, e.g., between a first time it takes for the one or more acoustic waves to travel between the inlet 812 and the first acoustic vent 808a and a second time it takes for the one or more acoustic waves to travel between the inlet 812 and the second acoustic vent 808b.

[0093] FIG. 9 illustrates an acoustic waveguide 900 disposed within a wearable head device according to an embodiment of the present disclosure. As shown, the acoustic waveguide 900 can include an acoustic source 902, a waveguide manifold 904, and one or more acoustic vents 908a-d. In some embodiments, the acoustic vents 808a-d can include an acoustic mesh as described above with respect to the acoustic vents 528a-d. As shown, the acoustic source 902 can be disposed on a front frame 932 of the wearable head device. In this manner, the weight of the acoustic source can be distributed to the bridge of the nose, allowing for a more comfortable weight distribution for the user. This also allows the temple portion 934 to be thinner and lighter than the temple portion supporting the audio source, for example, the right temple arm 2132 supporting the right speaker 2136. In some examples, the audio source 902 can be disposed on the temple portion 834. In one or more examples, the acoustic waveguide 900 can operate according to the process 700.

[0094] In some examples, the waveguide manifold 904 can be disposed in a temple portion 934, e.g., an arm, of the head wearable device. As shown, the waveguide manifold 904 can correspond to an acoustic manifold. In one or more examples, the waveguide manifold 904 can include an inlet 912 and one or more manifold branches 948a-d, each branch corresponding to an acoustic vent 908a-d. As shown, the waveguide manifold 904 can receive one or more sound waves 926a-d from the sound source 902a via the inlet 912. As shown, each branch 948a-d can connect the inlet 912 to a respective acoustic vent 908a-d. In such an embodiment, one or more acoustic waves 926a-926d generated by the acoustic source 902 can have separate, non-overlapping paths, with each path corresponding to one of the manifold branches 948a-948d leading to a respective acoustic vent 908a-908d. For example, an acoustic wave can be received through the inlet 912 of the waveguide manifold 904 and travel as acoustic wave 926a through branch 948a to acoustic vent 908a. Similarly, acoustic wave 926b can travel from the inlet 912 through branch 948b to acoustic vent 908b without substantial overlap with the path of acoustic wave 926a in branch 848a. In such an embodiment, when there is minimal overlap between the branches, e.g., branches 948a-948d, there can be better control of acoustic propagation, e.g., because there is no shared acoustic path for each of the one or more acoustic waves 926a-926d traveling through the waveguide manifold 904 via their respective branches 948a-948d.

[0095] In some embodiments, the distance between the inlet 912 and each acoustic vent 908a-908d can determine the timing of one or more acoustic waves 926a-926d emanating from a particular acoustic vent. In some examples, the distance between the inlet 912 and each acoustic vent 908a-908d can be adjusted such that a time delay between one or more acoustic waves emanating from adjacent vents, such as between a first acoustic vent 908a and a second acoustic vent 908b, corresponds to a difference between a first time it takes for a first acoustic wave 926a to travel from the inlet to the first vent 908a and a time it takes for a second acoustic wave 926b to travel from the inlet 912 to the second vent 908b.

[0096] FIG. 10A illustrates a sound system 1000 disposed within a wearable head device, according to an embodiment of the present disclosure. As illustrated, the sound system 1000 can include a transducer array 1002 including a number of transducers 1002a-d. Although four transducers are illustrated in the figure, one skilled in the art will understand that the transducer array can include any number of transducers without departing from the scope of the present disclosure. In some embodiments, the transducers can be disposed on a lower surface 1018 of a temple portion 1034 of the wearable head device. In one or more examples, the lower surface 1018 can include a number of openings 1008a-d, such that each transducer 1002a-d is disposed within or near a respective opening. For example, a first transducer 1002a can be disposed within a first opening 1008a, a second transducer 1002b can be disposed within a second opening 1008b, and so on. Each of the transducers 1002a-1002d can be configured to receive an audio signal and generate one or more acoustic waves based on the audio signal.

[0097] 10B illustrates a sound system 1050 according to an embodiment of the present disclosure. As shown, the sound system 1050 can include an audio source, a decoder 1054, a DSP 1056, a phase delay amplifier 1058, and a speaker array 1060. The phase delay amplifier can include phase delays 1062A-1062E and amplifiers 1064A-1064E, with each phase delay and corresponding amplifier associated with a transducer or speaker in the speaker array 1060. In some embodiments, each transducer can have a discrete signal path from a digital signal processing system (DSP) to a discrete amplifier. In some embodiments, each transducer can be phase correlated to an algorithm from the DSP to emit a beamforming (focused) pattern 1060, e.g., such that the beamforming pattern is directed toward the wearer's ear.

[0098] FIG. 11 illustrates a block diagram of a process 1100 for operating a sound system according to an embodiment of the present disclosure. In one or more examples, the process 1100 may correspond to the sound system illustrated in FIG. 10. In step 1102, the system may identify a position of a first ear relative to one or more sound sources of a head-wearable device. For example, the system may determine a distance between the one or more sound sources and the first ear. In some examples, the one or more sound sources may correspond to a transducer array 1002 of the sound system 1000. In some embodiments, identifying the position of the first ear may correspond to identifying an expected position of the ear relative to the one or more sound sources. In step 1104, the system may obtain an audio signal. In one or more examples, the audio signal may correspond to one or more sounds associated with an XR environment. In some embodiments, the audio signal may be generated and / or output continuously while a user is using the XR system (e.g., the XR system 200).

[0099] In step 1106, for each transducer, the system can determine a signal modification parameter based on the distance between the transducer and the first ear. In some examples, the signal modification parameter can correspond to a time delay. In step 1108, for each transducer, a signal modification can be applied to the audio signal of the corresponding transducer. For example, the first transducer 1002a may have a first time delay introduced to a first signal corresponding to the first transducer 1002a, and the second transducer 1002b may have a second time delay introduced to a second signal corresponding to the second transducer 1002b, where the first time delay and the second time delay are different. In this way, providing separate transducers can allow an acoustic system, for example, the sound system 1000, to have more control over the fine tuning of the delays and other signal processing applied to the audio signal set for each transducer.

[0100] In step 1110, an output signal can be determined based on the modified audio signal for each transducer, e.g., transducers 1002a-1002d. In step 1112, the output signal can be presented to the user's first ear 1030. For example, the output audio signal 1028 presented to the user's first ear 1030 can correspond to the individual outputs 1026a-1026d of each of the transducers 1002a-1002d. In this way, the output signal can be presented as an audio source having a frontal wavefront with respect to the user's ear. Thus, the sound heard by the user naturally includes the user's acoustic pinna signature.

[0101] The present disclosure relates to an acoustic waveguide and method of use for presenting an audio signal. An apparatus according to the present disclosure may include a waveguide member comprising a hollow body having a first end and a second end. The apparatus may further include an acoustic source disposed at the first end of the waveguide member configured to emit at least a first acoustic wave. The apparatus may further include a plurality of acoustic vents disposed on a lower surface of the body of the waveguide member, each of the plurality of acoustic vents configured to receive the first acoustic wave and further configured to emit a respective acoustic wave based on the first acoustic wave, each acoustic wave corresponding to a respective point sound source.

[0102] In some embodiments, the device may further include a sound absorber disposed at a second end of the waveguide member. In some embodiments, each of the plurality of acoustic vents corresponds to a respective point sound source. In some embodiments, the device is configured such that the first respective sound waves emitted from the first plurality of acoustic vents include sound frequencies within a predetermined range, and is further configured to filter sound frequencies below the predetermined range. The predetermined range may include one or more of 50 Hz to 150 Hz, 50 Hz to 250 Hz, 200 Hz to 500 Hz, and 400 Hz to 1 kHz. In some embodiments, the waveguide member is configured to propagate the first sound waves as longitudinal waves. In some embodiments, the body of the waveguide member may include a plurality of branches, each branch of the plurality of branches corresponding to one of the plurality of acoustic vents. In such embodiments, each branch of the plurality of branches may comprise a unique path between the first end of the waveguide member and the corresponding acoustic vent.

[0103] A device according to an embodiment of the present disclosure can include an acoustic mesh disposed across a corresponding opening of one or more of the plurality of acoustic vents. In some embodiments, the acoustic mesh can include at least one selected from a twill weave pattern, a plain weave pattern, a reverse plain weave, and a multiple twill weave. In some embodiments, the acoustic mesh can include a material having at least one of monofilament material characteristics, polyester characteristics, polyimide characteristics, polypropylene characteristics, polyamide characteristics, nylon material, and meta-aramid characteristics.

[0104] In some embodiments, the plurality of acoustic vents can be located on at least one of the temple side or the underside of the waveguide member. In some embodiments, the plurality of acoustic vents are arranged to propagate acoustic waves, including each of the respective acoustic waves, the acoustic waves having at least one of a predetermined propagation direction and a predetermined polar directivity pattern. In such embodiments, the predetermined polar directivity pattern can include at least one selected from a cardioid pattern, a highly cardioid pattern, and an irregular pattern.

[0105] An embodiment of the present disclosure may include a head-wearable device. For example, the head-wearable device may include a front frame, a display coupled to the front frame, an arm coupled to the front frame and configured to attach the head-wearable device to a user's head, and an acoustic waveguide. In one or more examples, the acoustic waveguide may include a waveguide member having a hollow body having a first end and a second end, an acoustic source disposed at the first end of the waveguide, and a plurality of acoustic vents disposed on a lower surface of the body of the waveguide, each of the plurality of acoustic vents configured to receive a first acoustic wave and further to emit a respective acoustic wave based on the first acoustic wave, each acoustic wave corresponding to a respective point sound source.

[0106] In some examples, the waveguide member may be disposed within the arm, hi some examples, the sound source may be disposed within the front frame.

[0107] In some examples, the acoustic waveguide may further include a sound absorber disposed at the second end of the waveguide member. In some examples, each of the plurality of acoustic vents may correspond to a respective point sound source. In some examples, the acoustic waveguide is configured such that the first respective sound waves emitted from the first plurality of acoustic vents include sound frequencies within a predetermined range, and is further configured to filter sound frequencies below the predetermined range. The predetermined range may include one or more of 50 Hz to 150 Hz, 50 Hz to 250 Hz, 200 Hz to 500 Hz, and 400 Hz to 1 kHz. In some examples, the waveguide member is configured to propagate the first sound waves as longitudinal waves. In some examples, the body of the waveguide member includes a plurality of branches, each branch of the plurality of branches corresponding to one of the plurality of acoustic vents. In such examples, each branch of the plurality of branches includes a unique path between the first end of the waveguide member and the corresponding acoustic vent.

[0108] A head wearable device according to an embodiment of the present disclosure may include an acoustic mesh disposed across a corresponding opening of one or more of the plurality of acoustic vents. In some embodiments, the acoustic mesh may include at least one selected from a twill weave pattern, a plain weave pattern, a reverse plain weave, and a multiple twill weave. In some embodiments, the acoustic mesh may include a material having at least one of monofilament material characteristics, polyester characteristics, polyimide characteristics, polypropylene characteristics, polyamide characteristics, nylon material, and meta-aramid characteristics.

[0109] In some embodiments, the plurality of acoustic vents can be located on at least one of the temple side or the underside of the waveguide member. In some embodiments, the plurality of acoustic vents are arranged to propagate acoustic waves, including each of the respective acoustic waves, the acoustic waves having at least one of a predetermined propagation direction and a predetermined polar directivity pattern. In such embodiments, the predetermined polar directivity pattern can include at least one selected from a cardioid pattern, a highly cardioid pattern, and an irregular pattern.

[0110] An embodiment of the present disclosure may include a method for presenting an audio signal. According to one or more embodiments, the method may include emitting one or more acoustic waves of an audio signal via an audio source into a waveguide member of an acoustic waveguide, receiving the one or more acoustic waves at a first acoustic vent, the first acoustic vent being disposed on a lower surface of the waveguide member, generating a first point sound source at the first acoustic vent based on the one or more acoustic waves, receiving the one or more acoustic waves at a second acoustic vent, the second acoustic vent being disposed on a lower surface of the waveguide member, generating a second point sound source at the second acoustic vent based on the one or more acoustic waves, presenting a first audio signal corresponding to the first point sound source, and presenting a second audio signal corresponding to the second point sound source.

[0111] In some examples, the method may further include absorbing one or more acoustic waves at a second end of the acoustic waveguide via a sound absorber, the second end being opposite the sound source disposed at the first end of the acoustic waveguide. In some examples, presenting the first sound source includes presenting a frontal wavefront to the ear of the user, and presenting the second sound source includes presenting the frontal wavefront to the ear of the user. In some examples, the body of the waveguide member includes a plurality of branches, each branch of the plurality of branches corresponding to one of the plurality of acoustic vents.

[0112] Although the disclosed examples have been fully described with reference to the accompanying drawings, it should be noted that various modifications and changes will become apparent to those skilled in the art. For example, the elements and / or components shown in the drawings may not be to scale and / or may be exaggerated for illustrative purposes. As another example, elements of one or more implementations may be combined, deleted, modified, or supplemented to form further implementations. Other combinations and modifications should be understood to be included within the scope of the disclosed examples, as defined by the appended claims.

Claims

1. 1. An apparatus comprising: a waveguide member comprising a hollow body having a first end and a second end; an acoustic source disposed at the first end of the waveguide member configured to emit at least a first acoustic wave; a plurality of acoustic vents disposed in the body of the waveguide member; Equipped with each of the plurality of acoustic vents is configured to receive the first acoustic wave and is further configured to emit a respective acoustic wave based on the first acoustic wave, each respective acoustic wave corresponding to a respective point sound source.

2. The apparatus of claim 1 , further comprising a sound absorber disposed at the second end of the waveguide member.

3. The apparatus of any one of claims 1 to 2, wherein each of the plurality of acoustic vents corresponds to a respective point sound source.

4. 3. The apparatus of claim 1, wherein the apparatus is configured such that each first sound wave emitted from the first plurality of acoustic vents includes audio frequencies within a predetermined range, and further configured to filter audio frequencies below the predetermined range.

5. 5. The apparatus of claim 4, wherein the predetermined range comprises one or more of: 50 Hz to 150 Hz, 50 Hz to 250 Hz, 200 Hz to 500 Hz, and 400 Hz to 1 kHz.

6. The apparatus according to any one of claims 1 to 2, wherein the waveguide member is configured to propagate the first acoustic wave as a longitudinal wave.

7. The apparatus of any one of claims 1 to 2, wherein the body of the waveguide member comprises a plurality of branches, each branch of the plurality of branches corresponding to one of the plurality of acoustic vents.

8. The apparatus of claim 7 , wherein each branch of the plurality of branches comprises a unique path between the first end of the waveguide member and the corresponding acoustic vent.

9. 3. The apparatus of claim 1, wherein one or more of the plurality of acoustic vents includes an acoustic mesh disposed across a corresponding opening of the one or more of the plurality of acoustic vents.

10. 10. The apparatus of claim 9, wherein the acoustic mesh comprises at least one selected from a twill weave pattern, a plain twill weave pattern, a reverse plain twill weave, and a multiple twill weave.

11. 10. The device of claim 9, wherein the acoustic mesh comprises a material having at least one of monofilament material properties, polyester properties, polyimide properties, polypropylene properties, polyamide properties, nylon material, and meta-aramid properties.

12. The device according to any one of claims 1 to 2, wherein the plurality of acoustic vents are located at least one of a temple portion of the waveguide member and a lower surface of the waveguide member.

13. 3. The apparatus of claim 1, wherein the plurality of acoustic vents are arranged to propagate acoustic waves, the acoustic waves including each of the respective acoustic waves, the acoustic waves having at least one of a predetermined propagation direction and a predetermined polar directivity pattern.

14. The apparatus of claim 13 , wherein the predetermined polar directivity pattern comprises at least one of a cardioid pattern, a highly cardioid pattern, and an irregular pattern.

15. A head-wearable device, The front frame and a display coupled to the front frame; an arm coupled to the front frame and configured to attach the head-wearable device to a user's head; An acoustic waveguide, the acoustic waveguide comprising: a waveguide member comprising a hollow body having a first end and a second end; an acoustic source disposed at the first end of the waveguide; a plurality of acoustic vents disposed in the body of the waveguide; an acoustic waveguide, each of the plurality of acoustic vents configured to receive a first acoustic wave and to emit a respective acoustic wave based on the first acoustic wave, each respective acoustic wave corresponding to a respective point sound source; A head-wearable device comprising:

16. The head-wearable device of claim 15 , wherein the waveguide member is disposed within the arm.

17. The head wearable device according to any one of claims 15 to 16, wherein the sound source is disposed within the front frame.

18. The head wearable device of any one of claims 15 to 16, further comprising a sound absorber disposed at the second end of the waveguide member.

19. The head wearable device of any one of claims 15 to 16, wherein each of the plurality of acoustic vents corresponds to a respective point sound source.

20. A head wearable device as described in any of claims 15 to 16, wherein the acoustic waveguide is configured so that each first sound wave emitted from the first plurality of acoustic vents includes audio frequencies within a predetermined range, and is further configured to filter audio frequencies below the predetermined range.

21. 21. The head-wearable device of claim 20, wherein the predetermined range includes one or more of 50 Hz to 150 Hz, 50 Hz to 250 Hz, 200 Hz to 500 Hz, and 400 Hz to 1 kHz.

22. The head wearable device according to any one of claims 15 to 16, wherein the waveguide member is configured to propagate the first acoustic wave as a longitudinal wave.

23. A head wearable device as described in any one of claims 15 to 16, wherein the main body of the waveguide member includes multiple branches, each branch of the multiple branches corresponding to one of the multiple acoustic vents.

24. 24. The head-wearable device of claim 23, wherein each branch of the plurality of branches comprises a unique path between the first end of the waveguide member and the corresponding acoustic vent.

25. 17. A head wearable device as described in any one of claims 15 to 16, wherein one or more of the plurality of acoustic vents includes an acoustic mesh positioned across a corresponding opening of the one or more of the plurality of acoustic vents.

26. 26. The head-wearable device of claim 25, wherein the acoustic mesh comprises at least one selected from a twill weave pattern, a plain twill weave pattern, a reverse plain twill weave, and a multiple twill weave.

27. 26. The head-wearable device of claim 25, wherein the acoustic mesh comprises a material having at least one of monofilament material properties, polyester properties, polyimide properties, polypropylene properties, polyamide properties, nylon material, and meta-aramid properties.

28. The head wearable device according to any one of claims 15 to 16, wherein the plurality of acoustic vents are located at least one of a temple portion of the waveguide member and a lower surface of the waveguide member.

29. A head wearable device as described in any of claims 15 to 16, wherein the plurality of acoustic vents are arranged to propagate acoustic waves, the acoustic waves including each of the respective sound waves, and the acoustic waves have at least one of a predetermined propagation direction and a predetermined polar directivity pattern.

30. 30. The head-wearable device of claim 29, wherein the predetermined polar directivity pattern includes at least one of a cardioid pattern, a highly cardioid pattern, and an irregular pattern.

31. A head-wearable device, The front frame and a display coupled to the front frame; an arm coupled to the front frame and configured to attach the head-wearable device to a user's head; An acoustic waveguide, the acoustic waveguide comprising: The audio source and a decoder coupled to the audio source and configured to generate an audio signal; a digital signal processor (DSP) configured to receive the audio signal from the decoder and generate a beamformed signal; a plurality of acoustic vents disposed on a lower surface of the acoustic waveguide; a plurality of sound transducers, each sound transducer disposed within a respective acoustic vent of the plurality of acoustic vents, each sound transducer configured to receive discrete output signals that are phase correlated to generate directional sound waves; an acoustic waveguide comprising: A head-wearable device comprising:

32. 1. A method for presenting an audio signal, comprising: emitting, via an acoustic source, one or more acoustic waves of an audio signal into a waveguide member of an acoustic waveguide; receiving the one or more acoustic waves at a first acoustic vent, the first acoustic vent being disposed on a lower surface of the waveguide member; and generating a first point sound source at the first acoustic vent based on the one or more acoustic waves; receiving the one or more acoustic waves at a second acoustic vent, the second acoustic vent being disposed on the lower surface of the waveguide member; and generating a second point sound source at the second acoustic vent based on the one or more acoustic waves; presenting a first audio signal corresponding to the first point sound source; presenting a second audio signal corresponding to the second point sound source; A method comprising:

33. 33. The method of claim 32, comprising absorbing the one or more acoustic waves at a second end of the acoustic waveguide via an acoustic absorber, the second end being opposite the first end of the acoustic waveguide.

34. 34. The method of claim 32, wherein presenting the first audio signal comprises presenting a frontal wavefront to the ear of a user, and wherein presenting the second audio signal further comprises presenting the frontal wavefront to the ear of the user.

35. The method of any of claims 32 to 33, wherein the body of the waveguide member includes a plurality of branches, each branch of the plurality of branches corresponding to one of a plurality of acoustic vents.

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