System for transmitting sound into and out of a listener's head using a virtual acoustic system

Abstract

Method for rendering an audio program (400) for headphones (100), the method comprising: Receiving (200) a location (402) for placing the sound program (400) in relation to a first earpiece (104) and a second earpiece (106) of the headphones (100); Determine (202) whether the location (402) lies between the first earpiece (104) and the second earpiece (106); according to a provision that the location (402) lies between the first earpiece (104) and the second earpiece (106), Filtering (302) the sound program (400) to generate a low-frequency component and a high-frequency component; Swiveling (306) the high-frequency component according to the location (402) to generate a first swiveled high-frequency component and a second swiveled high-frequency component; Combining (308) the low-frequency component and the first swung high-frequency component to generate a first signal (420) in the head; and Combining (308) the low-frequency component and the second swung high-frequency component to generate a second signal (422) in the head; Controlling the first earpiece (104) with the first signal (420) in the head; and Controlling the second earpiece (106) with the second signal (422) in the head.

Description

[0001] This non-preliminary application claims the benefit of the earlier filing date of the preliminary US application No. 62 / 566,087, filed on September 29, 2017. AREA

[0002] The present disclosure relates generally to the field of binaural sound synthesis; and in particular to binaural sound synthesis for sound that is closer to the listener than the near-field boundary. BACKGROUND

[0003] The human auditory system modifies incoming sounds by filtering them according to the sound's location relative to the listener. The modified sound incorporates a set of spatial guide tones, which the brain uses to determine the sound's position. Human hearing is binaural, meaning that two ears are used to perceive two sound pressure signals produced by a single sound.

[0004] Sound is transmitted through air by fluctuations in air pressure created by the sound source. These fluctuations propagate from the sound source to the listener's ears as pressure waves. The sound pressure waves interact with the environment along the path between the sound source and the listener's ears. In particular, the sound pressure waves interact with the listener's head and ear structure. These interactions modify the amplitude and phase spectrum of the sound depending on the sound's frequency, direction, and distance from the sound source.

[0005] These modifications can be described as a head-related transfer function (HRTF) and a head-related impulse response (HRIR) for each ear. The HRTF is a frequency response function of the ear. It describes how an acoustic signal is filtered by the reflective properties of the head, shoulders, and especially the pinna before the sound reaches the ear. The HRIR is a time response function of the ear. It describes how an acoustic signal is delayed and attenuated upon reaching the ear, due to the distance to the sound source and the shadowing of the sound source by the listener's head.

[0006] A virtual acoustic system is an audio system (e.g., a digital audio signal processor that renders an audio program into loudspeaker driver signals intended to drive a number of loudspeakers) that gives a listener the illusion that sound is emanating from somewhere in the room, when in fact the sound is emanating from loudspeakers located elsewhere. A common form of virtual acoustic system uses a combination of headphones (e.g., earphones) and binaural digital filters to recreate the sound as if it had arrived at the ears from a real source located somewhere in the room. Another example of a virtual acoustic system uses crosstalk-suppressed loudspeakers (or crosstalk-suppressed loudspeaker driver signals) to deliver a different sound pressure signal to each of the listener's ears.

[0007] Binaural synthesis transforms a sound source that contains no audible information about its position into a binaural virtual sound source that does contain audible information about the sound source's position relative to the listener. Binaural synthesis can use binaural filters to convert the sound source into the binaural virtual sound sources for each ear. The binaural filters respond to the distance and direction from the listener to the sound source.

[0008] Sound pressure levels for sound sources located relatively far from the listener will decrease in both ears at approximately the same rate as the distance from the listener increases. The sound pressure level at these distances decreases according to the spherical attenuation for distance from the listener. Sound sources at distances where sound pressure levels can be determined based on spherical attenuation can be described as far-field sound sources. The far-field distance is the distance at which sound sources begin to behave like far-field sound sources. The far-field distance is greatest for sounds lying on an axis passing through the listener's ears and smallest on a perpendicular axis passing through the midpoint between the listener's ears. The far-field distance on the axis passing through the listener's ears can be approximately 1.5 meters.The far-field distance on the vertical axis, passing through the midpoint between the listener's ears, can be approximately 0.4 meters. Sound sources at or greater a far-field distance from the listener can be modeled as far-field sound sources.

[0009] As a sound source approaches the listener, the effects of the interaction between the listener's head and body and the sound pressure waves become increasingly pronounced. The difference in sound intensity between the listener's ears is called the interaural level difference (ILD). A sound traveling toward the listener along the axis passing through their ears will increase in intensity at the ipsilateral ear and simultaneously decrease in intensity at the contralateral ear due to head shadowing effects. The ILD begins to increase at a distance of approximately 0.5 meters and becomes pronounced at a distance of approximately 0.25 meters.

[0010] The difference in the time it takes for a sound to arrive at the listener's ears is called the interaural time difference (ITD). The ITD also increases rapidly as a sound source moves toward the listener, and the difference in distances from the sound source to the listener's two ears becomes more pronounced. Sound sources at distances where the effects of the listener's head and body become significant can be described as near-field sound sources. Sound sources less than approximately 1.0 to 1.5 meters from the listener must be modeled with binaural filters that include these near-field effects (to simulate how a listener would hear them).

[0011] Modeling sound sources with binaural filters that include near-field effects can be effective for distances of approximately 0.25 meters or more. However, when the desired location of the sound source is very close to the listener, for example, less than approximately 0.25 meters, binaural filters that include near-field effects begin to produce binaural audio signals that have proven to be subjectively undesirable. Head shadowing effects can become so pronounced that the sound becomes inaudible at the contralateral ear, creating an uncomfortable sensation of occlusion in that ear.

[0012] Publication US 2016 / 0 119 737 A1 discloses an arrangement and a corresponding method for reproducing audio data of an acoustic scene. SUMMARY

[0013] The invention is defined in the independent claims. Advantageous embodiments are defined in the dependent claims. When it is desirable to reduce the distance to a perceived sound source in order to place the sound at a location between the listener's ears (also referred to as the location in the head), binaural filters based on HRTFs are no longer applicable. This is because HRTFs are derived from microphone measurements that capture the sound coming from sound sources located at a distance from the listener's head, the captured sound being naturally altered by the listener's head and shoulders. The measurements for deriving HRTFs can be performed using microphones located at the ears of a listener or in the ears of a mannequin head or acoustic model mannequin.

[0014] It would be desirable to provide a way to synthesize binaural audio signals (which would drive the respective earphone transducers at the left and right ears of a listener) for a virtual acoustic system to create the illusion of a sound source moving towards or away from the listener between i) the end of the effective area of ​​the near-field modeling and ii) the center of the listener's head or another location in the head.

[0015] In a device or method for rendering a headphone audio program, a location for placing the audio program relative to a first and a second earpiece is received. If the location is between the first and second earpieces (a location in the head), then the audio program is filtered to generate low-frequency and high-frequency components. The high-frequency component is panned according to the location to generate first and second high-frequency signals. The low-frequency component and the first high-frequency signal are combined to generate a first headphone driver signal for driving the first earpiece. A second headphone driver signal is generated similarly by combining the low-frequency component and the second high-frequency signal to generate a second signal located in the head. The audio program can be a stereo audio program.The device or method can provide for the rendering of the audio program at a location between the first earpiece and a near-field boundary. This location can vary over time, allowing the method, for example, to gradually move the audio program from a position inside the head to a position outside the head, or vice versa (e.g., from outside the head to a position inside the head).

[0016] The foregoing summary does not constitute an exhaustive enumeration of all aspects of the present disclosure. The disclosure is intended to include all practically implementable systems and methods derived from all suitable combinations of the various aspects summarized above, as well as those disclosed in the detailed description below and expressly mentioned in the claims. Such combinations may exhibit certain advantages not specifically mentioned in the above summary. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Various aspects of the revelation presented here are illustrated in an exemplary and non-exhaustive manner in the depictions of the accompanying drawings, in which identical references denote identical elements. It should be noted that references to “one” aspect in this revelation do not necessarily refer to the same aspect, and they signify at least one. Furthermore, in the interest of brevity and reducing the total number of figures, a given figure may be used to illustrate the features of more than one aspect of the revelation, and it may not be necessary for all the elements in the figure to represent a given aspect. Fig. Figure 1 shows a view of an exemplary listener wearing headphones. Fig. Figure 2 is a flowchart of part of a process for synthesizing a binaural program according to the distance of the sound from the listener. Fig. Figure 3 is a flowchart of part of a process for synthesizing a binaural program for a tone located in the area in the head between the earpieces on the listener's ears. Fig. Figure 4 is a block diagram for a section of a circuit for processing the sound program when the sound location is in the area in the head between the two earpieces. Fig. Figure 5 is a flowchart of a section of a process for synthesizing a binaural program for a tone located in the transition area between one of the two earpieces and the adjacent near-field boundary. Fig. Figure 6 is a block diagram for a section of a circuit for processing the tone program when the tone location is in the transition area between one of the two earpieces and the adjacent near-field boundary. Fig. Figure 7 is a block diagram for a section of a circuit for processing a stereophonic sound program when the sound location is in the area in the head between the two earpieces. Fig. 8 is a graph of the gains for each of the in Fig. 7 level controls shown. DETAILED DESCRIPTION

[0018] The following description details numerous specific aspects. However, it is understood that the aspects revealed can be implemented practically without these specific details. In other cases, generally known circuits, structures, and techniques have not been shown in detail so as not to complicate the understanding of this description.

[0019] The following description refers to the accompanying drawings, which illustrate several aspects of the present disclosure. It is understood that other aspects may be used and that mechanical, compositional, structural, electrical, and operational modifications may be made without deviating from the essence and scope of the present disclosure. The following detailed description is not to be understood in a limiting sense, and the scope of the invention is defined only by the claims of the granted patent.

[0020] The terminology used herein serves only the purpose of describing certain aspects and is not intended to limit the present disclosure. Spatially relative terms, such as "under," "below," "below," "above," "above," and the like, may be used herein for the simple purpose of describing the relationship of one element or feature to another element, other elements, another feature, or other features, as illustrated in the figures. It is understood that, in addition to the orientation illustrated in the figures, the spatially relative terms are intended to include various orientations of the device in use or operation. For example, if the device in the figures is inverted, elements described as "under" or "below" other elements or features would then be oriented "above" the other elements or features.Therefore, the exemplary term "below" can include both an orientation above and below. The device may be oriented differently (e.g., rotated by 90 degrees or in other orientations), and the spatially relative descriptors used herein can be interpreted accordingly.

[0021] As used here, the singular forms "ein", "eine", "eines" and "der", "die", "das" are intended to include the plural forms as well, unless the context indicates otherwise. It is further understood that the terms "umfasst" and / or "umfassend" indicate the presence of listed features, processes, elements, and / or components, but do not preclude the presence or addition of one or more other features, processes, elements, components, and / or groups thereof.

[0022] The terms "or" and "and / or," as used here, are to be interpreted as inclusive or as meaning any combination thereof. Therefore, "A, B, or C" or "A, B, and / or C" means "any one of the following: A; B; C; A and B; A and C; B and C; A, B, and C." An exception to this definition occurs only where a combination of elements, steps, or actions is in some way inherently mutually exclusive.

[0023] Fig. Figure 1 is a top view of an illustrative listener 100 wearing headphones 102 with a first earpiece 104 and a second earpiece 106 to present a different sound pressure signal to each ear of the listener. While in Fig. 1. Where headphones with a headband connected to the earpieces are shown, it should be clear that wired or wireless earphones can be used in a similar manner. For the purposes of this disclosure, the term "headphones" shall include on-ear headphones, over-ear headphones, earphones that lie outside the ear canal, in-ear headphones that are inserted into the ear canal, and other acoustic output devices that deliver a different sound program to each ear of the listener without the respective sound program of each ear being significantly crossed with that of the other ear of the listener.

[0024] Fig. Figure 1 shows a vector originating at the midpoint 110 between the two earpieces 104 and 106, which is generally the center of the user's head. The vector extends through the first earpiece 104, which is shown to be the earpiece for the right ear of the listener 100. The vector can be divided into regions by i) a boundary 114 at the earpiece 104, a boundary 118 where near-field HRTF becomes effective, and a boundary 122 where far-field HRTF becomes effective. A virtual acoustic system according to the present disclosure can select the processing for an audio signal according to a desired placement of the audio signal in one of the regions between these boundaries. It is understood that a similar vector can be extended through the second earpiece 106, which is shown to be the earpiece for the left ear of the listener 100, to provide corresponding regions on the opposite side of the listener.While the boundaries are represented as points on a vector, it is understood that they extend around the listener as three-dimensional surfaces. The distance from the center of the listener's head to a boundary can depend on the angle to that boundary. Therefore, the boundary surfaces are generally not spherical. For clarity, aspects of the revelation are described with reference to the vector. However, these aspects can also be applied to sounds located anywhere in three-dimensional space.

[0025] The areas created by the above boundaries can be described as an in-head area 112, a transition area 116, a near-field area 120, and a far-field area 124. The in-head area 112 is the area between the two earpieces 104 and 106. It can be considered as two symmetrical areas extending from the center 110 of the user's head to one of the earpieces 104 or 106. The transition area 116 is the area (outside the listener's head) between one of the earpieces 104 or 106 and the adjacent near-field boundary 118. The near-field area 120 is the area between the near-field boundary 118 and the far-field boundary 122. The far-field area 124 extends from the far-field boundary 122 away from the listener 100. Aspects of the present disclosure generate headphone driver signals for controlling the two earpieces 104, 106, which make it possible for a sound program to be placed in these different regions.

[0026] Fig. Figure 2 is a flowchart for a procedure for processing a sound program according to a specific rendering mode. The operations of the procedure can be performed by a working programmed digital processor operating on a digital sound program (e.g., including a digital audio signal). A sound location is received by a sound location classifier (operation 200). If the sound location is in the area in head 112 between the two earpieces (operation 202), processing occurs according to a first rendering mode, as described in Figure 2. Fig. 3 flowchart shown (operation 204). If the sound location is in the transition area 116 between one of the two earpieces and the adjacent near-field boundary (operation 206), processing takes place according to a second rendering mode, as shown in Fig. 5 shown in the flowchart (operation 208). If the sound location is in the near-field region 120 between the near-field boundary and the far-field boundary (operation 210), processing is carried out according to a third rendering mode, using a near-field model 212. Otherwise, processing is carried out according to a fourth rendering mode in a far-field model (operation 214).

[0027] Fig. Figure 3 is a flowchart for a method of processing a sound program when the sound location is in the area in the head 112 between the two earpieces (operation 202), according to one aspect of the present disclosure. Fig. 4 is an aspect of a section of a circuit for processing the sound program when the sound location is in the area in the head between the two earpieces 202.

[0028] The sound program is received by an audio receiver circuit 400 (operation 300). The desired sound location is received by a local receiver circuit 402. The audio receiver circuit 400 and the local receiver circuit 402 can be parts of a general receiver circuit. The local receiver circuit 402 can determine desired sound locations in addition to, or as an alternative to, receiving sound locations provided with the sound program. In one respect, the local receiver circuit 402 can interpolate sound locations between received sound locations to provide a smoother sense of the sound's movement. In another respect, the local receiver circuit 402 can deduce the sound locations from the sound program.

[0029] The audio program is filtered to generate a low-frequency component and a high-frequency component (operation 302). A low-pass filter 404 and a complementary high-pass filter 406 can be used to generate the low-frequency and high-frequency components of the audio program. Complementary here means that the two filters operate with attenuation of the filtered frequencies, so that combining the filtered sections produces a signal that is audibly similar to the unfiltered audio program.

[0030] The high-frequency component is pivoted according to its location to generate a first high-frequency pivoted component and a second high-frequency pivoted component (operation 306). The high-frequency component can be pivoted by a first level control 408 and a complementary second level control 410 to generate the first and second high-frequency pivoted components. Complementary here means that the two level controls operate with attenuation of the high-frequency component, so that the sound generated in the first earpiece 104 and the second earpiece 106 of the headphones 102 by the first and second high-frequency pivoted components would create an audible impression of the high-frequency component moving without attenuation between the earpieces (from the left earpiece or L).The ability of the first level control 408 to adjust its gain smoothly from high to medium to low, in response to a change in location from the left earpiece (L) through the center (C) and then to the right earpiece (R), is illustrated by the downward-sloping line shown in its box. Similarly, the ability of the second level control 410 to adjust its gain smoothly from low to medium to high, as the location changes from the left earpiece (L) through the center (C) and then to the right earpiece (R), is illustrated by the upward-sloping line shown in its box. In some respects, the high-frequency component can be attenuated to an inaudible level when the location of the sound is at the opposite earpiece; in other respects, the high-frequency component can be attenuated to a low but audible level when the location of the sound is at the opposite earpiece.

[0031] The first and second high-frequency swept components are each combined with the low-frequency component to generate the first and second signals in the head (operation 308). The signals in the head control the earpieces 104 and 106 of the headphones 102. The low-frequency and high-frequency swept components can be combined by audio mixers 412 and 414. A first audio mixer 412 receives the low-frequency component from the low-pass filter 404 and the first high-frequency swept component from the first level control 408 and combines the two audio signals to generate the first signal in the head 420 to control the first earpiece 104. A second audio mixer 414 receives the low-frequency component from the low-pass filter 404 and the second high-frequency swept component from the second level control 410 and combines the two audio signals to generate the second signal in the head 422 to drive the second earpiece 106.

[0032] The effect of a room impulse response can also be added to improve the quality of the virtual acoustic simulation. In this case, a first finite impulse response (FIR) filter 416, configured according to a desired room impulse response, can be applied to the combination of the low-frequency component and the first high-frequency swept signal to generate the first signal in the head 420 (as a first headphone driver signal). A second finite impulse response filter 418, configured according to a desired impulse response, can be applied to the combination of the low-frequency component and the second high-frequency swept signal to generate the second signal in the head 422 (as a second headphone driver signal).It is understood that the effect of room impulse responses can be added similarly to other circuits described below, which are shown without FIR filters for clarity. In other aspects, the effect of room impulse responses can be added elsewhere in the circuit, for example, as part of binaural filters (described further below), to better model the interaction between the listener and the virtual acoustic environment. In some aspects, the room impulse responses can change with head rotations of the listener.

[0033] The processing of the tone program, as described above, when the tone is located in the area of ​​the head between the two earpieces (operation 202), provides an audio output for both earpieces in which the low-frequency component of the tone program remains unchanged by the location of the tone, while the high-frequency component is panned between the two earpieces according to the location of the tone. This has been shown to result in a more comfortable listening experience, as the constant low-frequency component prevents the sensation of occlusion of the "far" ear when the location of the tone is close to one ear.

[0034] Fig. Figure 5 is a flowchart for a method for processing a sound program when the sound location is in the transition area 116 between one of the two earpieces 104, 106 and the adjacent near-field boundary 118, according to one aspect of the present disclosure. Fig. Section 6 is a section of a circuit for processing the tone program when the tone location is in the transition area 116. The tone program is received by an audio receiver circuit 600 (operation 500). The desired tone location is received by a local receiver circuit 602. The audio receiver circuit and / or the local receiver circuit can be connected to the circuit described in Fig. The circuit shown in section 4 can be divided, or they can be an additional audio receiver circuit and / or location receiver circuit that receives additional copies of the tone program and / or the location. The audio receiver circuit 600 and the location receiver circuit 602 can be parts of a general receiver circuit. The location receiver circuit 602 can determine desired tone locations in addition to, or as an alternative to, receiving tone locations provided with the tone program, as is the case for the location receiver circuit of Fig. 4 was described.

[0035] The tone program is processed by two binaural near-field filters 610, 614 to generate a near-field boundary signal for each earpiece (operation 502). Each of the two binaural near-field filters 610, 614 is configured to filter the tone program and thereby generate near-field boundary signals to enable a tone to be placed at a location on the near-field boundary 118. This is achieved by providing location input signals 612, 616 that are adapted to the near-field boundary closest to the desired location 602 of the tone program, rather than being located at the desired location 602 of the tone program itself. The location input signals 612, 616 serve to configure their respective binaural near-field filters 610, 614.

[0036] The first and second signals in head 606, 618 are received (operation 504). The first and second signals in head 606, 618 can be processed by the section of the in Fig. The circuit shown in section 4 is generated, configured such that its local receiver circuit 402 is tuned to the location of the earpiece that is closest to the desired location of the tone program, rather than being located at the desired location of the tone program. This is shown in Fig. 6 represented by locations 608, 620, which are labelled “near the ear”.

[0037] A mixing calculation circuit (mixing calculator 604) calculates a mixing factor (operation 506). The mixing factor is proportional to the distance between i) the desired location of the sound program and ii) the earpiece that is closest to the desired location of the sound program. For example, the mixing factor can be calculated as follows: |LocationSound−Locationearpiece||LocationNearfield boundary−locationearpiece|

[0038] It is understood that a mixing factor, calculated according to the equation above, has a value of 1 if the desired location of the sound program is [location]. Ton, at the near-field boundary, location Nahfeldgrenze The example mixing factor has a value of 0 if the desired location of the audio program is [location]. Ton , on the earpiece that corresponds to the desired location of the sound program, location Ohrstück which is closest. Other values ​​and ranges can be used for the mixing factor.

[0039] The near-field boundary signals and the signals in the head are swung based on the mixing factor (operation 508). The swung near-field boundary and the signals in the head are then combined to generate a first and a second signal in the head (operation 510). The first signal in the head 606 can be swung by a first level control 622. The first near-field boundary signal, which can be generated by the first binaural near-field filter 610, can be swung by a second level control 624. The first signal in the head 606 is the signal that would be provided to the first earpiece 104 for a tone located at the boundary 114. The first near-field boundary signal is the signal that would be provided to the first earpiece 104 for a tone located at the near-field boundary 118 that is closest to the first earpiece 104.The first and second level controls 622 and 624 are complementary and operate to create an audible impression of the sound moving between the first earpiece and the adjacent near-field boundary without attenuation. For example, at a given location, i) the near-field boundary signal is attenuated by a first amount proportional to one minus the mixing factor (calculated for that location), and ii) the first signal in the head is attenuated by a second amount proportional to the mixing factor.

[0040] The second signal in head 618 can be adjusted by a third level control 628. The second near-field boundary signal, which can be generated by the second binaural near-field filter 614, can be adjusted by a fourth level control 626. The second signal in head 618 is the signal that would be provided to the second earpiece 106 for a tone located at the boundary 114. The second near-field boundary signal is the signal that would be provided to the second earpiece 106 for a tone located at the near-field boundary 118 closest to the first earpiece 104. The third and fourth level controls 628 and 626 are complementary and work to create an audible impression of the tone moving between the first earpiece 104 and the adjacent near-field boundary 118 without attenuation.For example, at a given location i) the near-field limit signal is attenuated by a first amount proportional to one minus the mixing factor (calculated for that location), and ii) the second signal in the head is attenuated by a second amount proportional to the mixing factor.

[0041] The first swept signal in the head from the first level control 622 and the first swept near-field limit signal from the second level control 624 can be combined by a first audio mixer 630 to generate a first headphone signal 634, which is supplied to the first earpiece 104. The second swept signal in the head from the third level control 628 and the second swept near-field limit signal from the fourth level control 626 can be combined by a second audio mixer 632 to generate a second headphone signal 636, which is supplied to the second earpiece 106.

[0042] In some aspects, a first and a second mixing filter are provided, which receive the audio program and the mixing factor and generate a first and a second headphone signal, similar to the signals produced by the Fig. The circuit shown in section 6 can be generated. It can be advantageous to define the work processes that are generated by the circuit shown in the diagram. Fig. The circuit shown in Figure 6 illustrates that this can be achieved with a single mixing filter instead of by pivoting and combining the outputs of in-head and near-field filters, since the filters can exhibit frequency-dependent phase shifts that produce artifacts when combined. Thus, Fig. Figure 6 should be understood to show both a circuit implemented to combine signals from multiple filters and a circuit that uses mixed filters to produce the effect of combining signals from multiple filters.

[0043] For clarity of description, the above refers to the movement of a point sound source relative to the listener. However, aspects of this disclosure can also be applied to stereophonic sound sources. A stereophonic sound source can be recorded to provide left and right channels. Playing the left audio channel to the left ear and the right audio channel to the right ear produces sound that is perceived as being located in the listener's head and centered between the ears. Aspects of this disclosure can treat the movement of a stereophonic sound source from the center of the listener's head to one of the listener's ears as a transition from a stereophonic sound source to a monophonic sound source. This aspect, namely how a stereo source is treated as stereo in the head but then transitions to mono outside the head, is discussed further below in connection with Fig. 7 developed.

[0044] Fig. Figure 7 is an aspect of a section of a circuit for processing a stereophonic sound program when the sound location is in the area in the head between the two earpieces 202 (operating process 202). The stereo sound program is received by an audio receiver circuit 700. The sound program is filtered to generate a low-frequency component and a high-frequency component. One from a group of low-pass filters 706, 708 and one from a group of complementary high-pass filters 704, 710 can be used to generate the low-frequency and high-frequency components for each channel of the stereo sound program, as shown. Complementary here means that the two filters (low-pass and high-pass) operate with attenuation of the filtered low and high frequencies, so that combining the filtered sections produces a signal that is audibly similar to the unfiltered sound program.

[0045] The high-frequency portion of each channel is pivoted according to location to produce a first high-frequency pivoted portion for the ear intended to hear the channel and a second high-frequency pivoted portion for the opposite ear. For example, a first level control 712 can pivot the left channel as shown to provide an audio portion of the left channel to the left ear, while a second level control 714 pivots the left channel to provide an audio portion of the left channel to the right ear. Similarly, a third level control 718 can pivot the right channel as shown to provide an audio portion of the right channel to the right ear, and a fourth level control 716 can pivot the right channel to provide an audio portion of the right channel to the left ear, as shown.Mixers 722, 724 are provided to combine the outputs from level controls 712, 714, 716, 718 (as shown) to generate signals in head 726 and 728 respectively for each of earpieces 104, 106 on the headphone 102 worn by the listener 100.

[0046] Fig. Figure 8 is an example curve showing how the gains of the in Fig. The levels 712, 714, 716, and 718 shown vary (depending on the desired location of the audio program). If the stereo audio program is to be located at the center C of the listener's head (indicated by C along the x-axis of each of the gain curves shown in the boxes representing the four level controls), the audio component is provided with maximum gain by level controls 712 and 718 (for each channel) to the ear that is not intended to hear that channel, and with minimum gain by level controls 714 and 716 (for each channel) to the ear that is not intended to hear that channel. Thus, when the stereo audio program is located at the center C of the listener's head, the high-frequency component of the stereo audio program is provided to the listener in stereo.

[0047] If the stereophonic sound program is to be located at one of the listener's ears, the level controls 716 and 712 provide a consistently high gain to the audio component for the two channels fed to that ear (e.g., the left earpiece, L, shown on the x-axis of the gain curve), while level controls 718 and 714 provide a consistently low gain to the two channels for the opposite ear. The "high" gain for the channels directed toward the ear containing the stereo program can be a value that produces a monophonic sound program perceived as having essentially the same volume as the stereo program located at the center of the listener's head.The “low” gain for the channels directed towards the opposite ear can be chosen to avoid a feeling of occlusion, or it can be a level at which the high-frequency component of the stereophonic sound program is not perceptible.

[0048] When the location of the stereophonic sound program moves from the center of the listener's head to one of the listener's ears, the level controls 712, 714, 716, 718 pan each of the channel signals for each of the listener's ears, as shown in Fig. The curves shown in 8 indicate a smooth transition from a stereo program to a mono program.

[0049] Returning to Fig. Mixers 722 and 724 combine the high-frequency and low-frequency components of the audio program (mixer 722 receives all components of the left channel, both low and high, while mixer 724 receives all components—both low and high—of the right channel) with the outputs of level controls 712 and 716 (level controls for the left ear) and level controls 714 and 718 (level controls for the right ear) to generate the respective signals in the head 726 and 728. Alternatively, the low-frequency components of the stereo program can be processed as a monophonic program, which is delivered equally to both ears if the stereophonic audio program is located between the listener's ears (e.g., at location C). Fig. Figure 7 shows this aspect as dotted lines, where the outputs of low-pass filters 706 and 708 are not fed directly to mixer 722, but instead are routed through a mixer where they are combined and fed to both mixers 722 and 724. Under this scenario, it is understood that the left and right (unfiltered) channels of the stereo audio program could instead be combined by a mixer and then filtered through a single low-pass filter (essentially by combining filters 706 and 708 into a single filter after the mixer, shown as dotted lines) to generate the combined low-frequency components of the stereo program (which are then fed to both mixers 722 and 724).

[0050] For clarity of revelation, it was described above how a sound source moves along a path that passes through the center of the listener's head and through the listener's ears, e.g., where the in Fig. The vector shown lies along the positive x-axis or at an angle of zero degrees relative to the positive x-axis. However, aspects of the present disclosure can also be applied to paths into and out of the listener's head at various angles. If the transition into the head begins from a different angle, then the gains of the level controls and the location of the near-field boundary change. For tones moving along a path perpendicular to the path passing through the center of the listener's head and the listener's ears, e.g., at an angle of ninety degrees relative to that shown in Fig. With vector 1 shown, the gains of the level control do not change when the sound moves. For other angles, the gain values ​​of the level controls vary based on the compound angle between the line connecting the two ears and the line connecting the source to the center of the head.

[0051] For paths that pass through the area in the head 112 or the transition area 116, but not through the center of the listener's head, the path can be processed as transitions between a series of paths through the center of the listener's head at varying angles.

[0052] Although exemplary aspects have been described and shown in the accompanying drawings, it should be clarified that such aspects are merely illustrative and not limiting to the general invention, and that this invention is not limited to the specific constructions and designs shown and described, because those skilled in the art can recognize various other modifications. The description is therefore to be regarded as illustrative and not limiting.

Claims

[1] Method for rendering an audio program (400) for headphones (100), the method comprising: Receiving (200) a location (402) for placing the sound program (400) in relation to a first earpiece (104) and a second earpiece (106) of the headphones (100); Determine (202) whether the location (402) lies between the first earpiece (104) and the second earpiece (106); according to a provision that the location (402) lies between the first earpiece (104) and the second earpiece (106), Filtering (302) the sound program (400) to generate a low-frequency component and a high-frequency component; Swiveling (306) the high-frequency component according to the location (402) to generate a first swiveled high-frequency component and a second swiveled high-frequency component; Combining (308) the low-frequency component and the first swung high-frequency component to generate a first signal (420) in the head; and Combining (308) the low-frequency component and the second swung high-frequency component to generate a second signal (422) in the head; Controlling the first earpiece (104) with the first signal (420) in the head; and Controlling the second earpiece (106) with the second signal (422) in the head. [2] Method according to claim 1, wherein the sound program (400) is a stereo program including a first channel and a second channel, and according to a provision that the location (402) is between the first earpiece (104) and the second earpiece (106), Filtering the audio program (402) to generate the low-frequency component and the high-frequency component includes filtering the audio program (400) to generate the low-frequency component and the high-frequency component for each channel; the pivoting of the high-frequency component according to location (402) to generate a first high-frequency component and a second high-frequency component, includes pivoting the high-frequency component for each channel according to location (402) to generate the first pivoted high-frequency component and the second pivoted high-frequency component for each channel; combining the low-frequency component and the first high-frequency component to generate the first signal (420) in the head includes combining the low-frequency component of the first channel, the first swept high-frequency component of the first channel, and the second swept high-frequency component of the second channel to generate the first signal (420) in the head; and The combination of the low-frequency component and the second high-frequency component to generate the second signal (422) in the head includes combining the low-frequency component of the second channel, the first swept high-frequency component of the second channel, and the second swept high-frequency component of the second channel to generate the second signal (422) in the head. [3] Method according to claim 1, further comprising: Determine whether the location (402) lies between the first earpiece (104) and a near-field boundary, and according to a determination that the location (402) lies between the first earpiece (104) and the near-field boundary, a) Filtering (502) the tone program (400) with binaural near-field filters to generate a near-field limit signal for each earpiece (104, 106), b) Calculate (506) a mixing factor proportional to a distance between the location (402) and the first earpiece (104), c) Combining (510) i) the near-field boundary signal, attenuated by a first amount proportional to one minus the mixing factor, and ii) the first signal (420) in the head, attenuated by a second amount proportional to the mixing factor, to generate a first headphone driver signal to drive the first earpiece (104), and d) Combining (510) i) the near-field limit signal, attenuated by the first amount, and ii) the second signal (422) in the head, attenuated by the second amount, to generate a second headphone driver signal to drive the second earpiece (106). [4] Method according to claim 3, wherein the mixing factor has a value of 1 when the location (402) is at the first earpiece (104) and a value of 0 when the location (402) is at the near-field boundary. [5] Method according to claim 3, wherein the sound program (400) is a stereo program including a first channel and a second channel, and, according to a provision that the location (402) is between the first earpiece (104) and the near-field boundary, the method further comprises combining the first channel and the second channel to make the sound program (400) a monophonic program. [6] Method according to claim 1, further comprising applying a filter with limited impulse response (416, 418) to the first signal (420) in the head to generate a first headphone driver signal for driving the first earpiece (104), and applying the filter with limited impulse response (416, 418) to the second signal (422) in the head to generate a second headphone driver signal for driving the second earpiece (106). [7] Method for rendering an audio program (400) for headphones (100), the method comprising: Receiving (200) a location (402) for placing the sound program (400) in relation to a listener wearing the headphones (100) with a first earpiece (104) that is closer to the location (402) than a second earpiece (106); Determine (202) whether the location (402) lies between the first earpiece (104) and a near-field boundary; according to a determination that the location (402) lies between the first earpiece (104) and the near-field boundary, Filtering (502) the tone program (400) with first and second binaural near-field filters (610, 614) to generate a first near-field limit signal and a second near-field limit signal, Filtering the audio program (400) to generate a low-frequency component and a high-frequency component; Calculate (506) a mixing factor that is proportional to a distance between the location (402) and the first earpiece (104), Combining (510) i) the first near-field limit signal, attenuated by a first amount proportional to one minus the mixing factor, and ii) the low-frequency component, attenuated by a second amount proportional to the mixing factor, to generate a first headphone driver signal for driving the first earpiece (104), and Combining (510) i) the second near-field limit signal, attenuated by the first amount, and ii) the low-frequency component, attenuated by the second amount, to generate a second headphone driver signal to drive the second earpiece (106). [8] Method according to claim 7, wherein the mixing factor has a value of 1 when the location (402) is at the first earpiece (104) and a value of 0 when the location (402) is at the near-field boundary. [9] Method according to claim 7, wherein the sound program (400) is a stereo program including a first channel and a second channel, and, according to a provision that the location (402) is between the first earpiece (104) and the near-field boundary, the method further comprises combining the first channel and the second channel to make the sound program (400) a monophonic program. [10] Method for rendering a sound program (400) for headphones (100) at a sound position located in a transition region, the method comprising: Receiving (200) a location (402) for placing the sound program (400) in relation to a listener wearing the headphones (100) with a first earpiece (104) that is closer to the location (402) than a second earpiece (106); Determine (202) whether the location (402) lies between the first earpiece (104) and a near-field boundary; according to a determination that the location (402) lies between the first earpiece (104) and the near-field boundary, Filtering (502) the tone program (400) with first and second binaural near-field filters (610, 614) to generate a first near-field limit signal and a second near-field limit signal, Filtering the audio program (400) to generate a first signal (420) in the head and a second signal (422) in the head; Calculate (506) a mixing factor that is proportional to a distance between the location (402) and the first earpiece (104), Panning (508) of the first and second near-field limit signal and of the first (420) and second (422) signal in the head based on the mixing factor, Combining (510) i) the first near-field boundary signal, attenuated by a first amount proportional to one minus the mixing factor, and ii) the first signal (420) in the head, attenuated by a second amount proportional to the mixing factor, to generate a first headphone driver signal to drive the first earpiece (104), and Combining (510) i) the second near-field boundary signal, attenuated by the first amount, and ii) the second signal (422) in the head, attenuated by the second amount, to generate a second headphone driver signal to drive the second earpiece (106). [11] Method according to claim 10, wherein the combining of the first near-field limit signal and the first signal (420) in the head comprises mixing i) of a first filter that attenuates the first near-field limit signal by the first amount, and ii) of a second filter that attenuates the first signal (420) in the head by the second amount, to form a mixing filter for combining the first near-field limit signal and the first signal (420) in the head. [12] Method according to claim 10, further comprising applying a filter with limited impulse response (416, 418) to the combination of the first near-field limit signal and the first signal (420) in the head to generate the first headphone driver signal, and applying the filter with limited impulse response (416, 418) to the combination of the second near-field limit signal and the second signal (422) in the head to generate the second headphone driver signal. [13] Device for rendering a sound program (400) for headphones (100), the device comprising: a receiver that receives the sound program (400) and a location (402) for placing the sound program (400) with respect to a first earpiece (104) and a second earpiece (106) of the headphone (100); a low-pass filter (404) that generates a low-frequency component of the audio program (400); a high-pass filter (406) that generates a high-frequency component of the audio program (400); a level control (408, 410) that pivots the high-frequency component according to the location (402) when it is determined that the location (402) lies between the first earpiece (104) and the second earpiece (106) in order to generate a first high-frequency pivoted signal and a second high-frequency pivoted signal; and a mixer (412, 414) that combines the low-frequency component and the first high-frequency swept signal to generate a first headphone driver signal to drive the first earpiece (104), and combines the low-frequency component and the second high-frequency swept signal to generate a second headphone driver signal to drive the second earpiece (106) if it is determined that the location (402) lies between the first earpiece (104) and the second earpiece (106). [14] Device according to claim 13, wherein: the sound program (400) is a stereo program that includes a first channel and a second channel; the low-pass filter (404) generates the low-frequency component for each channel; the high-pass filter (406) generates the high-frequency component for each channel; The level control (408, 410) pivots the high-frequency component for each channel according to the determination via the location (402) to generate the first high-frequency pivoted signal and the second high-frequency pivoted signal for each channel; and The mixer (412, 414) combines the low-frequency portion of the first channel, the first high-frequency swept signal of the first channel and the second high-frequency swept signal of the second channel to generate the first headphone driver signal to drive the first earpiece (104) and combines the low-frequency portion of the second channel, the first high-frequency swept signal of the second channel and the second high-frequency swept signal of the second channel to generate the second headphone driver signal to drive the second earpiece (106). [15] Device according to claim 13, further comprising: a first (610) and second (614) binaural near-field filter, which generate a first near-field limit signal and a second near-field limit signal; and a logic unit for calculating a mixing factor that is proportional to a distance between the location (402) and the first earpiece (104); wherein the mixer (412, 414) combines the first near-field limit signal, attenuated by a first amount proportional to one minus the mixing factor, and ii) the first signal (420) in the head, attenuated by a second amount proportional to the mixing factor, to generate the first headphone driver signal for driving the first earpiece (104), and i) the second near-field limit signal, attenuated by the first amount, and ii) the second signal (422) in the head, attenuated by the second amount, to generate the second headphone driver signal for driving the second earpiece (106). [16] Device according to claim 15, wherein the mixing factor has a value of 1 when the location (402) is at the first earpiece (104) and a value of 0 when the location (402) is at a near-field boundary. [17] Device according to claim 15, wherein: the sound program (400) is a stereo program that includes a first channel and a second channel; the low-pass filter (404) generates the low-frequency component for each channel; the high-pass filter (406) generates the high-frequency component for each channel; the level control (408, 410) pivots the high-frequency component for each channel according to location (402) to generate the first high-frequency pivoted signal and the second high-frequency pivoted signal for each channel; and when it is determined that the location (402) lies between the first earpiece (104) and a near-field boundary, the mixer (412, 414) the low-frequency component of the first channel, the first high-frequency swept signal of the first channel and the second high-frequency swept signal of the second channel are combined to generate the tone program (400) located at the first earpiece (104); the near-field limit signal, attenuated by one minus the mixing factor, and the tone program (400), located at the first earpiece (104), attenuated by the mixing factor, are combined to generate the first headphone driver signal for driving the first earpiece (104), and the near-field limit signal, attenuated by one minus the mixing factor, and the low-frequency component of the second channel, attenuated by the mixing factor, are combined to generate the second headphone driver signal for driving the second earpiece (106). [18] Device according to claim 13, further comprising a filter with limited impulse response (416, 418) that filters the combination of the low frequency component and the first high frequency signal to generate a first headphone driver signal for driving the first earpiece (104), and filters the combination of the low frequency component and the second high frequency signal to generate a second headphone driver signal for driving the second earpiece (106). [19] Method for rendering a sound program (400) for headphones (100) using a virtual acoustic system, the method comprising: a) Receiving (200) a location (402) where an audio program (400) is to be rendered; b) Determining a rendering mode based on whether the received location (402) is in the head, in a transition region, in a near-field region or in a far-field region; and c) Processing the sound program (400) according to the determined rendering mode, wherein, if it is determined that the rendering mode is in the head, the processing of the sound program (400) includes the following: Feeding a high-frequency component of the audio program to a first level control (408) and a second level control (410), both of which respond to the locus (402), wherein the first level control (408) and the second level control (410) are complementary to each other from a left ear locus to a right ear locus and pass through a central ear locus; and Combining an output of the first level control (408) with a low-frequency component of the audio program (400) to generate a first signal (420) in the head to control a first earpiece (104), and combining an output of the second level control (410) with the low-frequency component of the audio program (400) to generate a second signal (422) in the head to control a second earpiece (106). [20] The method of claim 19, further comprising: Repeating a)-c) a multitude of times, each time with a different location, to move the sound program (400) from “in the head” and then into the transition area and then into the near field area. [21] Method according to claim 19, wherein the sound program (400) is a stereo program including a first channel and a second channel, and according to a provision that the location (402) is in the transition area between the first earpiece (104) and the near-field boundary, the processing of the sound program (400) according to the specified rendering mode comprises combining the first channel and the second channel to make the sound program (400) a monophonic program. [22] Method according to claim 21, wherein, in accordance with the provision that the location (402) is ‘in the head’, the processing of the sound program (400) according to the ‘in the head’ rendering mode comprises combining the low-frequency components, but not the high-frequency components, of the first channel and the second channel to make the sound program (400) a monophonic program that is delivered equally to both earpieces (104, 106). [23] Method according to claim 19, wherein the sound program (400) is a stereo program including a first channel and a second channel, and according to the provision that the location (402) is ‘in the head’, the processing of the sound program according to the ‘in the head’ rendering mode comprises combining the low-frequency components, but not the high-frequency components, of the first channel and the second channel to make the sound program (400) a monophonic program that is delivered equally to both earpieces (104, 106).

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