System and method for loudspeaker radiation mode and directivity adaptive adjustment using intensity flow

Abstract

In at least one embodiment, an audio system is provided. The audio system includes a loudspeaker array, a microphone array, and at least one controller. The loudspeaker array transmits a first audio output signal in a listening environment. The microphone array includes pairs of microphones to capture the first audio output signal. The at least one controller is programmed to receive the captured first audio output signal from the pairs of microphones and to determine a sound intensity of the captured first audio output signal. The at least one controller is further programmed to determine a location of a wall in the listening environment relative to the loudspeaker array based at least on the sound intensity of the captured first audio output signal for the pairs of microphones and to transmit a second audio output signal in a direction away from the location of the wall.

Description

SYSTEM AND METHOD FOR LOUDSPEAKER RADIATION MODE AND DIRECTIVITY ADAPTIVE ADJUSTMENT USING INTENSITY FLOWTECHNICAL FIELD

[0001] Aspects disclosed herein generally relate to a system and a method for loudspeaker radiation mode and directivity adaptive adjustment using intensity flow. These aspects and others will be discussed in more detail herein.BACKGROUND

[0002] Most home audio systems in the market were designed to have fixed radiation patterns. This entails that loudspeakers may not adjust a radiation directivity according to a relative position between the loudspeaker and a listener. In recent years, more and more smart loudspeakers are showing up in the market due to the increasing demand for voice assistance, smart homes, and consumers working from home. Most of such smart loudspeakers are designed to deliver fixed radiation patterns. The most popular smart loudspeaker is a loudspeaker that provides a 360- degree uniform sound radiation. By placing the loudspeaker in a middle of a room, those in the room can perceive similar listening experiences.

[0003] However, if a loudspeaker is placed near a wall or close to other barriers, especially for 360-degree loudspeakers, the reflection from the wall may interfere with a direct sound. This condition may cause the overall sound to be colored and unclear. Therefore, detecting a position of the loudspeaker in a room and adjusting a beam pattern of a loudspeaker may be needed.SUMMARY

[0004] In at least one embodiment, an audio system is provided. The audio system includes a loudspeaker array, a microphone array, and at least one controller. The loudspeaker array transmits a first audio output signal in a listening environment. The microphone array includes pairs of microphones to capture the first audio output signal. The at least one controller is programmed to receive the captured first audio output signal from the pairs of microphones and to determine asound intensity of the captured first audio output signal. The at least one controller is further programmed to determine a location of a wall in the listening environment relative to the loudspeaker array based at least on the sound intensity of the captured first audio output signal for the pairs of microphones and to transmit a second audio output signal in a direction away from the location of the wall.

[0005] In at least another embodiment, a method is disclosed. The method includes receiving a captured audio output signal from pairs of microphones in a microphone array and determining a sound intensity of the captured audio output signal for the pairs of microphones in the microphone array. The method further includes determining a location of a wall in a listening environment relative to a loudspeaker array based at least on the sound intensity of the captured audio output signal for each of the pairs of microphones and transmitting a first audio output signal in a direction away from the location of the wall.

[0006] In at least another embodiment, a computer-program product embodied in a non- transitory computer readable medium that is stored in memory and that is executable by at least one controller in an audio system is provided. The computer-program product includes instructions to receive a captured audio output signal from pairs of microphones in a microphone array and to determine a sound intensity of the captured audio output signal for the pairs of microphones in the microphone array. The computer-program product further includes instructions to determine a location of a wall in the listening environment relative to a loudspeaker array based at least on the sound intensity of the captured audio output signal for each of the pairs of microphones and to transmit a first audio output signal in a direction away from the location of the wall.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The embodiments of the present disclosure are pointed out with particularity in the appended claims. However, other features of the various embodiments will become more apparent and will be best understood by referring to the following detailed description in conjunction with the accompany drawings in which:

[0008] FIGURE 1 generally illustrates a sound intensity of an omnidirectional loudspeaker being placed at different locations in a listening environment;

[0009] FIGURE 2 generally illustrates an audio system for detecting an audio output signal transmitted by a loudspeaker array relative to a wall in a room and for adjusting a transmission of the audio output signal based on the directivity of the audio output signal in accordance with one embodiment;

[0010] FIGURE 3 generally depicts a top view of a circular loudspeaker array and woofer;

[0011] FIGURES 4A - 4B generally depict a first example and a second example, respectively, of a microphone array as positioned on a tops side of a loudspeaker array;

[0012] FIGURE 5 generally depicts a more detailed implementation of the system of FIGURE 2 in accordance with one embodiment; and

[0013] FIGURE 6 generally depicts an audio system for detecting the audio output signal transmitted by the loudspeaker array relative to the wall in the room and for adjusting an equalization transmission of the audio output signal based on the directivity of the audio output signal in accordance with one embodiment.DETAILED DESCRIPTION

[0014] As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.

[0015] For a home audio system with a fixed or omnidirectional radiation patterns, the sound may become unnatural or colored when the loudspeaker is placed close to a wall or other obstacles. This may occur due to a near-field interaction around the speaker, such as a reflected sound that interferes with a direct sound and thus led to frequency response alternations. Most beam adjusting solutions may be designed as a manual control, which may be inconvenient for end users.

[0016] To overcome the abovementioned problem, adaptive sound functionality has emerged in several loudspeaker products for the last several years. One type of adjustment only changes a frequency response of the sound. For example, the Harman Kardon Go Play 3 ® speaker can calibrate the speaker bass performance according to the received signal from the internal microphone. Another type of adjustment is to adapt the beampattem of loudspeakers using microphone array signals, such as described in US Publication No. 20180352324A1. In this case, the acoustic impedance at each of microphone’s position is calculated to determine the orientation of the loudspeaker. In addition, U.S. Patent Nos. 11,778,379 and 11,924,625 detect the walls by monitoring wall reflections in impulse responses measured by a microphone array. As set forth herein however, a system and a method is provided that utilizes microphone pairs to calculate an intensity flow to detect nearby walls, and then steering the beampattern according based on this information. A number of advantages may be realized as disclosed below based on the disclosed system and method.

[0017] In general, the disclosed system and / or method provides that any nearby wall(s) may be detected by identifying a direction of a sound intensity flow of an audio output signal. Sound intensity may be a physical quantity that represents a magnitude and a direction of sound energy flow through a point in space. When an omnidirectional loudspeaker is placed away from walls in a room, the reflection from walls may be averaged out and hence the sound intensity in the center of the loudspeaker is low in all directions. For example, for an omnidirectional loudspeaker, the sound intensity contributed by the direct sound at the center of the loudspeaker may be zero due to the symmetry. Therefore, in this case, the sound intensity may only be affected by wall reflections. This may be illustrated by way of FIGURE 1 in which a sound intensity for a plurality of loudspeakers 102a, 102b are positioned in different locations 104a, 104b, respectively, in a room or listening environment 100. Various arrows 106 as shown with the loudspeakers 102a, 102b areintended to illustrate or indicate a direction and magnitude of the sound intensity (or sound intensity 106) associated with the loudspeakers 102a, 102b. As generally shown at loudspeaker 102a as being positioned proximate to a wall 110a, due to a mirror source 108, the sound intensity 106 at the center of loudspeaker 102 is high in a direction that is opposite to the nearby wall 110a. The mirror source 108 is generally prevalent in room acoustics. The reflection from the wall 110a may be considered as coming from a virtual source that is mirrored to a real source. In general, all walls 110a - l lOd (hereafter “walls 110”) in the room 100 produce mirror sources 108. However, only the nearby mirror sources 108 have a significant effect on the sound intensity at the source position.

[0018] In contrast and as shown with the loudspeaker 102b which is positioned or placed away from walls 110 of the room 100, the sound intensity 106 is generally equal in reference to each wall 110. The disclosed system and / or method seeks to determine the location of the wall 110 and / or the number of walls 110 relative to the loudspeakers 102a, 102b. In general, the sound intensity in any direction may be measured with two microphones that is aligned in that direction. High sound intensity may be an indicator of nearby walls that are positioned close to a loudspeaker 102 that is opposite to the direction at which the loudspeaker 102 transmits an audio output signal. In the case of one or more of the walls 110 have been detected, a radiation mode of the audio output signal as transmitted from the loudspeaker 102 may change such that a large portion of the sound energy of the audio output signal is be directed in a direction opposite to the wall(s) 110.

[0019] FIGURE 2 generally depicts an audio system 140 (or the system 140) for detecting an audio output signal transmitted by a loudspeaker array 152 relative to a wall 110 in a room 100 and for adjusting a transmission of the audio output signal based on the directivity of the audio output signal in accordance with one embodiment. The system 140 includes a microphone array 160, at least one digital signal processor (DSP) 162, an amplifier 164, and the loudspeaker array 152. It is recognized that the DSP 162 may also be referred to as a controller 162. It is recognized that the controller 162 may execute instructions stored on memory either positioned on the controller 162 itself or elsewhere in the system 140 to execute any of the operations performed by the DSP 162 and / or the amplifier 164.

[0020] The loudspeaker array 152 may include loudspeakers that are positioned along a horizontal plane or axis relative to the walls 110. Thus, in this regard, the loudspeakers within the array 152 may transmit an audio output signal at an angle that is generally perpendicular to the walls 110 of the room 100. The microphone array 160 may include any number of microphones positioned therein. The microphones positioned within the array 160 may be parallel to the loudspeaker array 152. The DSP 162 (or the controller 162) may automatically detect a location of the walls 110 by examining the audio output signal as captured by the microphone array 160 (e.g., the captured audio output signal) in response to the loudspeaker array 152 originally transmitting the audio output signal. Upon detecting (or determining) the location of the wall 110 relative to the location of the loudspeaker array 152, the controller 162 may then adjust the radiation or beam pattern of the audio output signal as transmitted by the loudspeaker array 152 into the room 100 to account for the close proximity of the wall 110 to the loudspeaker array 152. In general, the controller 162 may employ an adaptive process or scheme to detect location of the loudspeaker array 152 relative to the wall 110 in response to receiving an audio input signal 172 from a mobile device (not shown) or other audio playback mechanism. The microphone array 160 may output the captured audio output signal that provides a sound field that changes relative to the wall 110. The controller 162 may use this aspect as a basis that the loudspeaker array 152 is positioned proximate or close to one or more of the walls 110. Once the location of the wall 110 is determined relative to the loudspeaker array 152, the controller 162 may then radiate the audio output signal away from the detected wall 110.

[0021] Prior to discussing the detection aspect of the loudspeaker array 152 relative to the wall 110 further, additional aspects related to a setup of the loudspeaker array 152 will be discussed in more detail in connection with FIGURE 3. For example, the loudspeaker array 152 may be configured to output an audio output signal in a uniform radiation pattern as generally shown in FIGURE 3. For example, the loudspeaker array 152 may be circular and include a total of eight loudspeakers 180a- 180f that are equally spaced apart from one another. The loudspeakers 180a - 180f positioned in the array 152 may be positioned along a horizontal place such that the audio output therefrom is generally configured to travel along a horizontal axis toward a respective wall 110 in the room 100.

[0022] The array 152 may include a woofer 182 positioned in a mid-section or center of the array 152. For example, the various loudspeakers 180a - 180f may surround the woofer 182. Each of the loudspeakers 180a - 180f may transmit audio in the mid-high frequency range and the corresponding radiation pattern may be adjusted based on wall detection results. The woofer 182 may transmit a low-midrange audio output vertically. For example, the woofer 182 may be facing upwards or downwards in the room 100 while remaining loudspeakers 180 may be positioned in the middle of the array 152. The arrangement of the loudspeaker array 152 as illustrated herein generally radiates the sound energy associated with the audio output signal evenly to all directions when the loudspeaker 180 or the array 152 are transmitting the audio in an omni-directional mode, particularly at low frequencies. However, it is recognized that the reflections of the audio output signal from the loudspeaker array 152 off of the wall(s) 110 may not be uniformly distributed along 360-degree spaces. The woofer 182 may be arranged to radiate sound associated with the audio output signal uniformly and along 360-degree spaces horizontally.

[0023] Similarly, FIGURES 4A - 4B illustrate additional aspects related to the loudspeaker array 152 and the microphone array 160. The microphone array 160 includes a plurality of microphones 160a - 160d. In general, the different microphone arrays 160 as illustrated in FIGURES 4A and 4B exhibit that differing microphone arrays 160 may be used in connection with the system 140. In each of FIGURES 4A and 4B, it can be seen that the microphone array 160 includes a plurality of microphones 160a - 160d arranged in a circular or radial pattern. With reference to FIGURE 4A, the microphone array 160 may be positioned either on top of the loudspeaker array 152 or on the bottom of the loudspeaker array 152. A single microphone 160d may be positioned within a center of the array 160. For example, the microphones 160a - 160c may surround the single microphone 160d. With respect to FIGURE 4 A, the controller 162 may determine or calculate an intensity flux for each microphone pair. For example, the controller 162 may determine an intensity flux for each of the following microphone pairs: (1) microphone 160d and microphone 160a; (2) microphone 160d and microphone 160b, and (3) microphone 160d and microphone 160c in response to an audio output signal being transmitted by the loudspeaker array 152. Then, the controller 162 may determine which microphone pair exhibits or captures the maximum intensity of the audio output signal. In this case, the controller 162 determines that the microphone pair thatdetects the maximum intensity is indicative of the audio output signal that is being transmitted in a direction that is opposite to one of the walls 110.

[0024] FIGURE 4B also generally another implementation of the loudspeaker array 152 and the microphone array 160. Similarly, and as noted above, the controller 162 may use pair of the microphones 160a - 160d relative to the loudspeakers 190a - 190h to capture the audio output signal and to compute the intensity the captured audio output signal to determine the direction of the wall 110. For example, the controller 162 may determine an intensity flux for each of the following microphone pairs: (1) microphone 160a and microphone 160b; (2) microphone 160b and microphone 160c, and (3) microphone 160c and microphone 160d ; and (4) microphone 160d and microphone 160a in response to an audio output signal being transmitted by the loudspeaker array 152. The microphones 160a - 160d may be positioned on side wall(s) of the loudspeakers 190a - 190g. Then, the controller 162 may determine which microphone pair exhibits or captures the maximum intensity of the audio output signal. In this case, the controller 162 determines that the microphone pair that detects the maximum intensity is indicative of the audio output signal that is being transmitted in a direction that is opposite to one of the walls 110.

[0025] It should be noted that the number of microphones utilized in the array 160 may vary based on the desired criteria of a particular implementation. For example, as few as three microphones 190 may be used to detect the wall(s) 110 relative to the loudspeaker array 152 in 360 degrees. If it is only necessary to determine a single direction, then the microphone array 160 may only include at least two microphones.

[0026] Referring now to FIGURE 2, the system 140 may operate in two modes. For example, the system 140 may operate in a preset sound mode. In the preset sound mode, the controller 162 transmits the audio output signal that is a predetermined signal in terms of frequency and other characteristics. The audio output signal is provided to the loudspeaker array 152 via the controller 162 such that the loudspeaker array 152 transmits the audio output signal into the room 100. At that point, the microphone array 160 receives the transmitted audio output signal and provides the same to the controller 162. The controller 162 then records the captured audio output signal. The controller 162 employs filters to filter the mid and high frequency components present on thecaptured audio output signal to leave the low frequency component in the signal as transmitted from the woofer 182 for evaluation. As noted above, the woofer is positioned within the loudspeaker array 152.

[0027] The controller 162 may then determine the direction of the wall 110 by monitoring the for the maximum intensity provided by one of the microphone pairs. Upon detecting the direction of the wall 110, the controller 162 then enters into a speaker playing mode such that controller 162 controls the loudspeaker array 152 to transmit the audio output signal into the room 100 via a beamforming implementation to direct the audio output signal towards listeners in the room 100 as opposed to a direction toward the wall 110. In this case, the system 140 is able to transmit the audio output signal to listeners in the room 100 without influence of the wall(s) 110 which inherently provides sound clarity and minimal to no sound coloration issues. Stated differently, the system 100 may transmit the audio output signal into the room 100 that is not saddled with sound clarity and with coloration issues given that the system 140 has knowledge of the direction of the wall 110 and that the system 140 employs beamforming to transmit the audio output signal into the room 100 without being negatively influenced by the presence of the wall(s) 110.

[0028] FIGURE 5 depicts a more detailed implementation of the system 140 of FIGURE 2 in accordance with one embodiment. The controller 162 includes a transfer path estimation block 200, a first filter 202, a second filter 204, a sound intensity calculation block 206, a boundary estimation block 208, and a beamforming block 210. The amplifier 164 may include a first amplifier 164a for amplifying the audio output provided by the woofer 182 (e.g., that is part of the loudspeaker array 152). The amplifier 164 may include a second amplifier 164b for amplifying the audio output provided by the loudspeaker array 152 (e.g., the mid-range loudspeakers 180 that form the loudspeaker array 152 as shown in connection with FIGURE 3). The first filter 202 may be a low pass filter, for example, to enable the low frequency component of the audio input signal 172 to be amplified by the amplifier 164b. In addition, the second filter 204 may be high pass filter, for example, to enable a high frequency component of the audio input signal 172 to be amplified by the amplifier 164a.

[0029] In general, with the transfer path estimation block 200 is programmed to define a transfer function from a reference signal to an output provided on the captured audio output signal as detected by the microphone array 160. In general, the transfer path estimation block 200 estimates (measures) the transfer function from the reference signal to the outputs provided by the microphones of the microphone array 160. The reference signal corresponds to an input to the transfer path that is being measured. The reference signal may be transmitted to the loudspeaker array 152. For example, the input or output of the amplifier 164a may be used as a reference signal. The reference signal may also be transmitted to the woofer 182. In this regard, the input or output of the amplifier 164b may also be used as the reference signal.

[0030] The microphone signal (e.g., output of the microphone array 160 or output of the various pairs of microphones) may include direct sound, reflected sound, and noise that may be not related to the audio output signal sent to the loudspeaker. Thus, the transfer path estimation block 200 may remove this uncorrelated noise and maintain the direct sound and reflect sound for the detected nearby wall reflections.

[0031] In this regard, the transfer path estimation block 200 estimates the transfer function by executing an acoustic echo canceller (AEC) algorithm. In general, the controller 162 estimates the transfer function prior to calculating the sound intensity of the captured audio output signal. In the case of a high signal to noise ratio environment, this operation may be omitted.

[0032] The controller 162 may execute the AEC algorithm based on equations (1) - (3) as set forth below. For example, r(n) denotes a reference signal, mj(n) denotes the output from the jthmicrophone which can modeled as:

[0034] Where v(n) is a noise signal, * is a convolution operator, hj(n) is an impulse response of a transfer path from reference to the microphone. Since the noise and the reference may be typically uncorrelated, it is possible to estimate an impulse responses h(n) by an adaptive linear filtering algorithm, such as, for example, a Normalized Least-Mean-Square (NLMS) algorithm expressed as:

[0037] where e7(n), h}(n), gNLMSand ^NLMS are the instantaneous estimation error, estimated impulse response, step size, and a small positive constant used to avoid division by zero, respectively.

[0038] After the transfer path is estimated, the controller 162 may utilize the noise-removed signal r(n) * h}(n) or the impulse response h7(n) itself for the sound intensity calculation.

[0039] The sound intensity calculation block 206 may then perform an intensity calculation on the captured audio output signal as provided ty the microphone array 160. In general, the sound intensity calculation block 206 may utilize a two-probe method as set forth below in equation (4) to determine the sound intensity.

[0040] F or example, the two-probe estimation of a time-averaged sound intensity in time-domain is given by:

[0042] where pAis the sound pressure measured by microphone A in the microphone array 160 and pBis the sound pressure measured by microphone B in the microphone array 160 (e.g., where microphone A and microphone B form a microphone pair as disclosed in connection with FIGURES 4A or 4B). The operation (pA+ pB) f (pA— pB)dt (e.g., Eq. (4)) represents a time average of (pA+ pB) f (pA— pB)dt, where p is a density of air and Ar is a distance between the two microphones 160a - 160d in the microphone array 160. The time-averaged sound intensity represents a net sound power flow from one microphone to another microphone in a microphone pair of the array 160, and thus this is used as a measure of nearby mirror sources. In a frequency domain, the controller 162 may calculate the sound intensity by:P240022WG

[0044] where SABis the estimation of cross power spectrum of the two microphones 190, Im() is the operator of taking the imaginary part of a complex number.

[0045] In general, the controller 162 computes the sound intensity for each pair of microphones (e.g., 160d - 160a, 160d - 160b, 160d, - 160c) (e.g., see FIGURE 4A for reference) in the microphone array 160. For FIGURE 4B, the controller 162 computes the sound intensity for each pair of microphones (e.g., 160a - 160b, 160b - 160c, 160c - 160d, and 160d - 160a and also, optionally, 160a - 160c and 160b - 160c). The boundary estimation block 208 determines whether there is a nearby wall 110 to the loudspeaker array 152. In general, the boundary estimation may be seen as a classification problem. For example, various classifiers can be used for this purpose. Such classifiers may include linear classification, logistic regression, Naive Bayes, Support Vector Machine, and neural networks.

[0046] The possible outcomes may include no wall or a best ‘opposite wall’ direction with, for example, a 45 degrees resolution. The boundary estimation block 208 may determine the possible outcomes: (1) no wall, (2) one wall, or (3) two walls (with the loudspeaker array 152 being placed at a comer of two walls 110). For each new product (or loudspeaker array 152), it is possible to collect training data by measuring the sound intensities of each pair of microphones 160a - 160d with the loudspeaker array 152 being placed at many different positions. The data will be labelled and fed to a training algorithm as executed by the controller 162 for a determination as to whether the machine learning model is considered successful. Once the machine learning model is considered successful, the controller 162 may be deployed along with the loudspeaker array 152. In general, the nearby walls 110 are detected if the absolute value of sound intensity along at least one pair of microphones 190 is large, and the wall direction will be along the maximum intensity.

[0047] After the controller 162 has detected a direction of wall 110, the controller 162 may then exit preset sound mode (e.g., detection mode) and stop the detection function until the controller 162 is controlled to perform this function again. After locating the direction of the wall, the controller 162, for example, may enter into a loudspeaker beamforming mode and control or set a beamforming target angle based on the direction of the wall 110 relative to the loudspeaker array 152. For example, if the wall is detected at 0 degrees rearward to the loudspeaker array 152,controller 162 (or beamforming block 21) may adjust a beamforming target angle at 180 degrees (e.g., adjust the audio output signal to be transmitted from the loudspeaker array 152 at 180 degrees) to avoid a reflection that would otherwise normally cause sound coloration. On the other hand, if the controller 162 does not detect a wall nearby, then the controller 162 may continue to transmit the audio output signal from the loudspeaker array 160 in a normal manner (e.g., without any adjustments to the transmission angle of the audio).

[0048] In general, there should be at least one direction in which the sound intensity of the captured audio output signal from a particular microphone pair exceeds a predetermined threshold in order for the controller 162 to determine the direction (or the presence) of the wall 110. Stated differently, the controller 162 determines the direction of the wall 110 (or the location of the wall 110) in response to the sound intensity of the captured audio output signal from a particular microphone pair in the microphone array 160 exceeding a predetermined threshold. If the controller 162 determines that the sound intensity for the captured audio output signal for all of the microphone pairs of the microphone array 160 are below the predetermined threshold, then the controller 162 determines that there are no nearby walls 110 to the loudspeaker array 152. In general, by measuring or monitoring the sound intensity provided by the various microphone pairs of the microphone array 160, the controller 162 is then able to determine that the loudspeaker array 152 is positioned with a predetermined distance of one or two walls 110 within the room 100 and that such a condition may cause the wall reflections issue as noted above. By understanding that the loudspeaker array 152 is positioned within the predetermined distance of the one or more walls 110, this information indicates the direction of the wall 110 and / or the location of the wall 110 relative to the loudspeaker array 152. Given that the controller 162 may determine the loudspeaker array 152 is positioned within a predetermined distance of the one or more walls 110 relative to the loudspeaker array 152, the controller 162 may direct the loudspeaker array 152 to direct the audio output signal away from the one or more walls 110. I

[0049] The beamforming block 210 may execute a weighted delay-and-sum approach as part of a loudspeaker beamforming algorithm. The weighed delay-and-sum approach may be given by,

[0051] where N, wt, x, y and Ttare the number of loudspeakers 180 in the array 152, a weight for each z-thspeaker (180), the audio input signal 172, the audio output signal and a delay for each zthmicrophone (e.g., 190), respectively. It is recognized that the beamforming block 210 may employ additional complex beamforming techniques to steer the audio beams (or the audio output signal).

[0052] FIGURE 6 depicts an audio system 250 (“the system 250”) for detecting the audio output signal transmitted by the loudspeaker array 152 relative to the wall 110 in the room 100 and for adjusting an equalization transmission of the audio output signal based on the directivity of the audio output signal in accordance with one embodiment. Similar to the system 140 noted above in connection with FIGURE 5 the system 250 includes the microphone array 160, the controller 162, the amplifier 164, and the loudspeaker array 152. The controller 162 includes the transfer estimation block 200, the sound intensity calculation block 206, the boundary estimation block 208, and a boundary equalizer block 212. In general, the transfer estimation block 200, the sound intensity calculation block 206, and the boundary estimation block 208 as illustrated in connection with FIGURE 6 operate similarly to that described in connection with FIGURE 5. In general, upon the controller 162 detecting location of the wall 110 in the room 100 based on the capture audio output signal, the boundary estimation block 208 may control various equalization parameters as set forth in the boundary equalizer block 212 to adjust the equalization of the audio output signal as provided by the loudspeaker array 152 including the woofer 182. In general, the transfer path estimation block 200, the sound intensity calculation block 206, and the boundary estimation block 208 operate in a similar manner as described in connection with FIGURE 5.

[0053] The controller 162 as noted in connection with FIGURE 6 seeks to determine whether ( 1 ) no walls are present, (2) one wall 110 is present, or (3) two walls are present (e.g., loudspeaker array 152 is located in a comer of the room 100). Upon determination that either one wall 110 is present or two walls 110 are present, the controller 162 may control equalization aspects for the audio output signal. For example, upon detecting that the loudspeaker array 152 is positioned proximate to one wall 110 (i.e., the controller 162 determines the location of one wall 110 relative to the loudspeaker array 152), the controller 162 controls the boundary equalizer block 212 to employ first preset equalization parameters. Upon detecting that the loudspeaker array 152 ispositioned proximate to two walls 110 (i.e., the controller 162 determines the location of two walls 110 relative to the loudspeaker array 152), the controller 162 controls the boundary equalizer block 212 to employ second preset equalization parameters. Each of the first and second preset equalization parameters may involve the controller 162 controlling the boundary equalizer block 212 to attenuate low frequency components on the audio output signal to compensate for the bass boost due to wall reflections. The boundary equalizer block 212 may include a cascading set of two or more biquad infinite impulse response (IIR) filters. The equalization parameters for each biquad IIR filter may include center frequency, gain, and Q-factor. The preset eq for a condition may include a lower gain for when a two-wall condition is detected (or located). Thus, in this regard, the second preset equalization parameters may involve a lower gain for the center frequency than that of gain applied to the center frequency associated with the first preset equalization parameters.

[0054] In general, the above disclosure identifies various limitations of a loudspeaker system that transmits an audio output signal into room (or listening environment) with a fixed radiation pattern, such as, for example, 360-degree loudspeakers. To automatically reduce the coloration and enhance the performance of these types of loudspeakers, the disclosed system and method utilize microphone arrays 160 to auto-detect wall reflection of the audio output signal based on an intensity flow calculation and therefore adjust the playing mode (e.g., directivity of the audio output signals) of the speaker array.

[0055] In general, the controller 162 may process the captured audio output signal and perform transfer function estimation, intensity flow calculation, and boundary estimation. Based on the detection results (e.g., detection of the direction of the wall relative to the loudspeaker array 152), the discloses system 140 adjusts the transmittivity (or adjusts the angle or orientation) of the audio output signal as transmitted by the loudspeaker array 152.

[0056] Aspects provided herein which provides the disclosed solution of performing, for example, the wall detection (or direction of the wall or location of the wall) by using a low- frequency signal (or component) of the audio output signal. Therefore, the tweeters (or high frequency loudspeakers) in the loudspeaker array 152 do not need to be uniformly distributed alonga circle to have 360 radiation patterns for emitting audio output signals. Similarly, the woofer 182 of the loudspeaker array 152 and the microphone array 160 may not to be symmetrically placed or positioned so long as a calibration of the sound intensities in the “no wall” condition is performed during the product development phase. The disclosed system and method provide the following advantages such as an intensity-based approach that is sensitive to nearby walls, and less sensitive to any small reflecting surfaces. On the contrary, systems and methods that search for wall reflections in an impulse response, as described in U.S. Patent Nos. 11,778,379 and 11,924,625, may have difficulties distinguishing the direct sound and reflections from nearby walls and such systems and methods may be prone to error due any small reflecting surfaces.

[0057] The phase difference between microphone pairs may be considered when computing the sound intensity. This aspect may make the detection more robust under microphone sensitivity errors compared to pure magnitude-based methods.

[0058] The disclosed wall detection solution may achieve various sound radiation modes combined with beamforming. For example, the disclosed wall detection solution may be used on applications such as voice assistance, teleconference conference devices, etc. to reduce the influence of the wall reflection and to further enhance the sound performance of the speaker. The disclose system may also need multichannel beamforming from a single device.

[0059] It recognized that the controllers as disclosed herein may include various microprocessors, integrated circuits, memory devices (e.g., FLASH, random access memory (RAM), read only memory (ROM), electrically programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM), or other suitable variants thereof), and software which co-act with one another to perform operation(s) disclosed herein. In addition, such controllers as disclosed utilizes one or more microprocessors to execute a computerprogram that is embodied in a non-transitory computer readable medium that is programmed to perform any number of the functions as disclosed. Further, the controller(s) as provided herein includes a housing and the various number of microprocessors, integrated circuits, and memory devices ((e.g., FLASH, random access memory (RAM), read only memory (ROM), electrically programmable read only memory (EPROM), electrically erasable programmable read onlymemory (EEPROM)) positioned within the housing. The controller(s) as disclosed also include hardware-based inputs and outputs for receiving and transmitting data, respectively from and to other hardware-based devices as discussed herein.

[0060] While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification Eire words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.

Claims

WHAT IS CLAIMED IS:

1. An audio system comprising: a loudspeaker array for transmitting a first audio output signal in a listening environment; a microphone array including one or more pairs of microphones to capture the first audio output signal; and at least one controller programmed to: receive the captured first audio output signal from each of the pairs of microphones; determine a sound intensity of the captured first audio output signal for each of the pairs of microphones; and determine a location of a wall in the listening environment relative to the loudspeaker array based at least on the sound intensity of the captured first audio output signal for each of the pairs of microphones; and transmit a second audio output signal in a direction away from the location of the wall.

2. The audio system of claim 1, wherein the at least one controller is further programmed to compare the sound intensity of the captured first audio output signal for each of the pairs of microphones to a predetermined threshold.

3. The audio system of claim 2, wherein the at least one controller is further programmed to determine the location of the wall based at least on the sound intensity of the captured first audio output signal for a corresponding pair of microphones that exceeds the predetermined threshold.

4. The audio system of claim 3, wherein the at least one controller is further programmed to establish a beamforming target angle for transmitting the second audio output signal in the direction away from the location of the wall.

5. The audio system of claim 3, wherein the at least one controller is further programmed to perform boundary estimation to determine whether the loudspeaker array is positioned in one of near one wall, near two walls, or no walls.

6. The audio system of claim 1, wherein the at least one controller is further programmed to perform a transfer path estimation corresponding to an estimate of a transfer function from a reference signal to an output provided by each microphone pair.

7. The audio system of claim 6, wherein the reference signal corresponds to the first audio output signal as provided from the at least one controller to an amplifier that amplifies the first audio output signal.

8. The audio system of claim 1, wherein the at least one controller is further programmed to transmit the second audio output signal with first preset equalization parameters in response to the loudspeaker array being positioned proximate to one wall.

9. The audio system of claim 8, wherein the at least one controller is further programmed to transmit the second audio output signal with second preset equalization parameters in response to the loudspeaker array being positioned proximate to two walls.

10. The audio system of claim 1, wherein the microphone array is positioned on the loudspeaker array.

11. A method comprising: receiving a captured audio output signal from pairs of microphones in a microphone array; determining a sound intensity of the captured audio output signal for the pairs of microphones in the microphone array;determining a location of a wall in a listening environment relative to a loudspeaker array based at least on the sound intensity of the captured audio output signal for each of the pairs of microphones; and transmitting a first audio output signal in a direction away from the location of the wall.

12. The method of claim 11, further comprising comparing the sound intensity of the captured audio output signal for the pairs of microphones to a predetermined threshold.

13. The method of claim 12, further comprising determining the location of the wall based at least on the sound intensity of the captured audio output signal for a corresponding pair of microphones that exceeds the predetermined threshold.

14. The method of claim 13 further comprising establishing a beamforming target angle for transmitting the first audio output signal in the direction away from the location of the wall.

15. The method of claim 13 further comprising performing boundary estimation to determine whether the loudspeaker array is positioned in one of near one wall, near two walls, or no walls.

16. The method of claim 11 further comprising performing a transfer path estimation corresponding to an estimate of a transfer function from a reference signal to an output provided by each microphone pair.

17. The method of claim 16, wherein the reference signal corresponds to the first audio output signal as provided from at least one controller to an amplifier that amplifies an audio output signal.

18. The method of claim 11 further comprising transmitting the first audio output signal with first preset equalization parameters in response to the loudspeaker array being positioned proximate to one wall.

19. The method of claim 18 further comprising transmitting the first audio output signal with second preset equalization parameters in response to the loudspeaker array being positioned proximate to two walls.

20. A computer-program product embodied in a non-transitory computer readable medium that is stored in memory and that is executable by at least one controller in an audio system to: receive a captured audio output signal from pairs of microphones in a microphone array; determine a sound intensity of the captured audio output signal for the pairs of microphones in the microphone array; determine a location of a wall in the listening environment relative to a loudspeaker array based at least on the sound intensity of the captured audio output signal for each of the pairs of microphones; and transmit a first audio output signal in a direction away from the location of the wall.

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