Patent Publication Number: US-9894454-B2

Title: Multi-channel audio capture in an apparatus with changeable microphone configurations

Description:
BACKGROUND 
     Technical Field 
     The exemplary and non-limiting embodiments described herein relate generally to the detection and capture of audio signals and, more particularly, to the analysis of directional information of audio signals detected and captured by a mobile device. 
     Brief Description of Prior Developments 
     Spatial audio capture involves the capture of sound for the subsequent reproduction and artificial re-creation of the sound. One type of spatial audio capture is binaural audio capture, in which microphones capture directional information as sound in a horizontal plane for the re-creation of the sound via speakers arranged to produce a three-dimensional (3-D) audio sensation through headphones. Another type of spatial audio capture is multichannel 5.1 audio capture, in which microphones capture directional information as sound in the horizontal plane and re-create that sound through five full-bandwidth channels and one low frequency effect channel to produce a 3-D audio sensation. 
     SUMMARY 
     The following summary is merely intended to be exemplary. The summary is not intended to limit the scope of the claims. 
     In accordance with one aspect, an apparatus comprises: at least one processor, and at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to: provide an audio capture event wherein one or more microphone configurations are configured to provide one or more audio signals based on at least one acoustic signal from at least one acoustic source, at least one of the one or more microphone configurations being defined by a first position of a first microphone configuration on a first portion and a second position of a second microphone configuration on a second portion, the second portion being movable relative to the first portion. 
     In accordance with another aspect, a method comprises providing an audio capture event wherein one or more microphone configurations are configured to provide one or more audio signals based on at least one acoustic signal from at least one acoustic source, at least one of the one or more microphone configurations being defined by a first position of a first microphone configuration on a first portion and a second position of a second microphone configuration on a second portion, the second portion being movable relative to the first portion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing aspects and other features are explained in the following description, taken in connection with the accompanying drawings, wherein: 
         FIG. 1A  is a perspective view of a mobile device in a video capture orientation; 
         FIG. 1B  is a schematic representation of positions of microphones in the mobile device in the orientation of  FIG. 1A ; 
         FIG. 2A  is a perspective view of the mobile device with a cover thereof closed; 
         FIG. 2B  is a schematic representation of positions of microphones in the mobile device in the orientation of  FIG. 2A ; 
         FIG. 3A  is a perspective view of the mobile device in an audio capture orientation; 
         FIG. 3B  is a schematic representation of positions of microphones in the mobile device in the orientation of  FIG. 3A ; 
         FIG. 4  is a graphical representation of the calculation of an angle of sound arriving at a device having a plurality of microphones; 
         FIG. 5A  is a perspective view of a camera with a lens cover in a closed position; 
         FIG. 5B  is a top view of the camera of  FIG. 5A  showing positions of microphones in the camera; 
         FIG. 6A  is a perspective view of a camera with a lens cover in an open position; 
         FIG. 6B  is a top view of the camera of  FIG. 6A  showing positions of microphones in the camera; 
         FIG. 7  is a perspective view of a camera in a landscape orientation showing locations of four microphones; 
         FIG. 8  is a perspective view of a camera in a video call orientation showing locations of four microphones; 
         FIG. 9  is a schematic view of a device showing a part that is moved to open and close a port in which a microphone is located; 
         FIG. 10  is a schematic view of a device showing a part that is moved to open and close a port to move an apparent location of a sensor in the device; and 
         FIG. 11  is a flow of one exemplary method of optimizing audio capture parameters in real time for a mobile device. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENT 
     Directional detection of sounds from one or more sound sources is optimal when the sound sources are arranged on the same plane with three or more directional microphones. In detecting the direction of sounds through such microphones, whether the sound source is located above or below a horizontal plane cannot be discerned. Nevertheless, when the microphone plane is horizontal, knowing whether the sound source was above or below the plane is of little value, since playback of the sound in a multichannel 5.1 audio format cannot reproduce sounds from above or below the horizontal plane. Furthermore, knowing whether the sound is above or below the horizontal plane is not very useful for playback in a binaural format. On the other hand, if the microphone plane is vertical, then “above the plane” can refer to “in front of the device” and “below the plane” can refer to “behind the device” (or vice versa). In vertical orientations of the microphone plane, whether the sound emanates from in front of or behind the device is useful information. 
     Stereo audio can be recorded with two omni-directional microphones that are separated from each other in a horizontal direction. Directional microphones generally cannot be used for recording stereo audio in such a configuration because of their directionality, which facilitates their operability only in certain orientations. 
     However, there are many uses for directional microphones in mobile devices. Such uses include, for example, surround sound capture for video recordings and surround sound teleconferencing. In any use, however, the microphones provide for an audio capture event such as a pure audio capture (receipt of audio without further processing), audio recording, audio/visual recording, or any other use case associated with receiving an audio signal. 
     A mobile device may be used in different physical orientations depending on the use scenario. Video is usually recorded on a mobile device when the mobile device is in a landscape orientation. In teleconferencing in which multiple people are providing audio input without video, however, the mobile device, which is generally a mobile phone, is usually laid flat on a table or other surface. During teleconferencing that includes video, the mobile device is usually held in a user&#39;s hand or placed on a surface so as to remain in a portrait orientation. In order to make the device work in different orientations (both landscape and portrait), more microphones are needed than is required to make the device work in only one orientation. In the past, additional microphones have been incorporated into mobile devices to render the mobile devices operable in multiple orientations. 
     Referring now to the Figures, in some embodiments described herein, audio capture parameters in real time can be optimized by adjusting the locations of microphones relative to other microphones. To do so, the microphones are located on a moving part of a mobile device (e.g., a slidable, foldable, or otherwise operable part), or the mobile device itself may be bendable or otherwise configurable by the user. 
     In other embodiments, microphones may be intentionally located on moving parts of the mobile device such that when the parts are moved, various effects may be realized. For example, upon moving parts of the mobile device, an application may be triggered to start, a microphone may move to a location that provides for the optimal capture of audio for the application, and/or another sensor may be revealed (e.g., a camera or additional microphone may be revealed from behind the moving part). 
     In still other embodiments, a microphone may be located on a moving part of the mobile device such that in one position of the moving part the microphone is optimal for recording in one orientation of the mobile device and in another position of the moving part the microphone is optimal for another orientation of the mobile device. 
     In still other embodiments, a moving part of the mobile device may be used to open and close microphone ports so that the effective microphone position varies. In such embodiments, the moving part may simultaneously start an application for which the new effective microphone position is preferred over the previous microphone position. Additionally, or in the alternative, the moving part may reveal another sensor or a camera. 
     In still other embodiments, a user interface (UI) may prompt a user to move the moving part so that microphones are moved to an optimal position for a current application. This can be done, for example, by providing audio output to the user through a headphone audio system where quality problems caused by suboptimal microphone locations are exaggerated or, for example, cause the illumination of a light near the microphone that should be moved. 
     Referring more specifically now to  FIG. 1A , a mobile device is designated generally by the reference number  100  and is hereinafter referred to as “device  100 .” Device  100  comprises a handset  110  having a slidable cover  120 . As shown, a first microphone  130  is located on the handset  110 , and a second microphone  140  and a third microphone  150  are located on the slidable cover  120 . When the device  100  is positioned in a landscape mode for video recording, a horizontal plane  160  is generally perpendicular to the device  100 . When the horizontal plane  160  is generally perpendicular to the device  100 , the microphones  130 ,  140 ,  150  are positioned relative to each other on the horizontal plane as shown in  FIG. 1B  in which the first microphone  130  is separated from the second microphone  140  by a distance h and the second microphone  140  is separated from the third microphone by a distance d. In this mode, the microphones  130 ,  140 ,  150  are in optimal recording positions for video recording. 
     However, when the device  100  is closed and positioned flat on a table or other surface as shown in  FIG. 2A  in preparation for an audio teleconferencing application, a vertical plane  170  is generally perpendicular to the device  100 . In this configuration of the microphones, the same microphones  130 ,  140 ,  150  are positioned on the vertical plane  170  and thus generally cannot be used for detecting sound source directions since the distance h≈0, as shown in  FIG. 2B . 
     Referring now to  FIG. 3A , when the slidable cover  120  is opened for the audio teleconferencing application, the microphones  130 ,  140 ,  150  are moved to optimal positions. Referring now to  FIG. 3B , the distances d and h can be used for the capture of spatial audio directly from the microphones  130 ,  140 ,  150 . The small elevation distance z ( FIG. 3A ) denoting the distance between the second microphone  140  located on the slidable cover  120  and the first microphone  130  located on the handset  110  is negligible as long as h is approximately greater than z. 
     Referring to  FIGS. 1A-3B , the presence of a non-zero distance h enables the microphones  130 ,  140 ,  150  of the device  100  to discern whether a sound is arriving from in front of or behind the device  100 . 
     To determine the optimal positions for the microphones  130 ,  140 ,  150  in the audio teleconferencing application, a method of directional analysis which is directly based on a correlation between audio channels defined by positions of the microphones  130 ,  140 ,  150  is selected. The direction of arriving sound is estimated independently for B frequency domain subbands in an effort to find the direction of a perceptually dominating sound source for every subband. 
     In such a method of directional analysis, every input channel k=1, . . . , 3 is transformed to a frequency domain using discrete Fourier transform (DFT). Sinusoidal windows with 50% overlap and an effective length of 20 milliseconds (ms) are used. Before the DFT transform D tot =D max +D HRTF , zeroes are added to the end of the window. D max  corresponds to the maximum delay in samples between the microphones. In the microphone setup presented in  FIGS. 1A and 1B , the maximum delay is obtained as: 
                     D   max     =       d   ⁢           ⁢     F   s       v             (   1   )               
where F s  is the sampling rate of signal and v is the speed of the sound in the air. D HRTF  is the maximum delay caused to the signal by head-related transfer function (HRTF) processing. After the DFT transform, the frequency domain representation X k (n) of all three channels, k=1, . . . , 3, n=0, . . . , N−1, is presented. N is the total length of the window considering the sinusoidal window (length N s ) and the additional D tot  zeroes.
 
     Frequency domain representation is divided into B subbands:
 
 X   k   b ( n )= X   k ( n   b   +n ),  n= 0, . . . ,  n   b+1   −n   b −1,  b= 0, . . . ,  B− 1  (2)
 
where n b  is the first index of the bth subband. The widths of the subbands can follow, for example, the equivalent rectangular bandwidth (ERB) scale.
 
     For every subband, the directional analysis is performed. In doing so, the direction in which a sound source is located is estimated using two audio channels (for example, the channels defined by the positions of the second microphone  140  and the third microphone  150 ). The task is to find delay τ b  that maximizes the correlation between two channels for subband b. Frequency domain representation of, e.g., X k   b (n), can be shifted τ b  time domain samples using: 
     
       
         
           
             
               
                 
                   
                     
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     Now the optimal delay is obtained from: 
                       max     τ   b       ⁢           ⁢     Re   (       ∑     n   =   0         n     b   +   1       -     n   b     -   1       ⁢           ⁢     (         X     2   ,     τ   b       b     ⁡     (   n   )       ⋆       X   3   b     ⁡     (   n   )         )       )       ,       τ   b     ∈     [       -     D   max       ,     D   max       ]               (   4   )               
where Re indicates the real part of the result and denotes the complex conjugate. X 2,τ     b     b  and X 3   b  are considered vectors with length of n b+1 −n b  samples. Resolution of one sample is generally suitable for the search of the delay. With the delay information, a sum signal is created using the following logic:
 
     
       
         
           
             
               
                 
                   
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     In the sum signal, the content of the channel in which an event occurs first is added as such, whereas the channel in which the event occurs later is shifted to obtain the best match. Shift τ b  indicates how much closer the sound source is to the second microphone  140  than the third microphone  150 . The actual distance can be calculated as: 
     
       
         
           
             
               
                 
                   
                     Δ 
                     23 
                   
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     Utilizing basic geometry on the setup in  FIGS. 1A and 1B , and referring now to  FIG. 4 , it can be calculated that the angle of the arriving sound from a source  180  is equal to: 
                       α   .     b     =     ±       cos     -   1       (         Δ   23   2     +     2   ⁢   b   ⁢           ⁢     Δ   23       -     d   2         2   ⁢   db       )               (   7   )               
where d is the distance between the second microphone  140  and the third microphone  150  and where b is the estimated distance between the source  180  and the nearest microphone (the second microphone  140 , as shown in  FIG. 4 ). Typically b can be set to a fixed value. For example, b=2 meters has been found to provide stable results.
 
     There are two alternatives for the direction of the arriving sound as the exact direction cannot be determined with only two microphones. One is from the front and the other is from behind the microphones. The third microphone is utilized to define which of the signs in equation (7) is correct: 
                       max     δ   b       ⁢           ⁢     Re   (       ∑     n   =   0         n     b   +   1       -     n   b     -   1       ⁢           ⁢     (         X     2   ,     δ   b       b     ⁡     (   n   )       ⋆       X   1   b     ⁡     (   n   )         )       )       ,       δ   b     ∈     [       -       hF   s     v       ,       hF   s     v       ]               (   8   )               
where δ b  is the delay between first and second channels (X 1  and X 2 ), the first channel being shifted relative to the second channel to achieve maximum correlation, and the delay being calculated for each frequency band b. If δ b  is positive, then the source  180  is closer to the second microphone  140  than the first microphone  130  and thus α b  is positive:
 
                     α   b     =     {               α   .     b             δ   b     ≥   0               -       α   .     b               δ   b     &lt;   0           .               (   9   )               
Thus, it can be determined for each frequency band which direction the sound is coming from. In particular, h is the height of the triangle and depends on whether the cover is open or closed and in which orientation the phone is placed. This h can be calculated when the microphone placement and the cover position are known. For example:
 
     
       
         
           
               
               
             
               
                   
               
               
                 H (meters) 
                   
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                 0.01 
                 Landscape orientation, cover closed, 
               
               
                   
                 device thickness = 10 millimeters (mm) 
               
               
                 0.0001 
                 Teleconference orientation, cover closed 
               
               
                 0.0199 
                 Teleconference orientation, cover open, 
               
               
                   
                 slide distance = 20 mm 
               
               
                   
               
            
           
         
       
     
     In other exemplary embodiments, a slidable camera lens cover can be used to optimize microphone positions in different applications. One microphone may be placed on a camera lens cover over a camera lens in a mobile device. The microphone positions in the device body and the lens cover may be such that when the lens cover is closed the microphone positions are optimal for recording speech for voice communications, and when the cover is open the microphone positions are optimal for recording stereo video. 
     Referring now to  FIGS. 5 and 6 , an example of such an arrangement is shown. As shown in  FIGS. 5A and 5B , for high quality noise cancellation for voice communications, a device  200  (such as a camera) has a first microphone  230  on a body portion  210  and a second microphone  240  on a slidable cover  220 . The device  200  is configured such that the microphones  230 ,  240  are arranged to be close to each other. The microphones  230 ,  240  are also located so that they are close to the user&#39;s mouth when the device  200  is held in a normal talking position. If the microphones  230 ,  240  are close and aligned as shown in  FIG. 5A , beamforming may be used to obtain optimal voice quality in noisy environments. However, the same positioning may be less than desirable with regard to obtaining stereo recording in a video recording using the device  200  since the distance d in  FIG. 5B  is essentially zero. 
     As shown in  FIG. 6A , when the second microphone  240  is on the slidable cover  220  of the device  200  (when the device  200  is a camera and the slidable cover  220  is a lens cover over a lens  265 ), then the slidable cover  220  is moved when the camera is used for video recording. The position to which the second microphone  240  moves when the slidable cover  220  is opened is more suitable for stereo recording since, as shown in  FIG. 6B , the distance d is greatly increased relative to the distance d as shown in  FIG. 5B . 
     Referring now to  FIGS. 7 and 8 , another example of such an arrangement is shown. A mobile device  300  may be configured to have four microphones, namely, a first microphone  310 , a second microphone  320 , a third microphone  330 , and a fourth microphone  340 , arranged as shown in  FIG. 7 . The first microphone  310  is located on a slidable member such as a slidable lens cover  350 , which is located adjacent to a display  360  on a surface of the mobile device  300 . Such an arrangement of microphones on the mobile device  300  is optimal for noise cancellation with beamforming in normal voice communications and also for multichannel audio capture during videography using the mobile device in a landscape orientation. 
     However, the arrangement of  FIG. 7  may not be optimal for video calls, where the mobile device  300  is held in a portrait orientation and where stereo audio is desired, as shown in  FIG. 8 . In particular, if the slidable lens cover  350  is not moved to an open position to expose a lens  355 , a distance D separating the first microphone  310  and the second microphone  320  (when both microphones are located on a plane  370 ) would be zero, as shown in  FIG. 7 . In such a configuration of the microphones, stereo recording would be impossible. Also, in holding the mobile device  300  in the portrait orientation, as shown in  FIG. 8 , the third microphone  330  and the fourth microphone  340  would be blocked by the user&#39;s hand. 
     As shown in  FIG. 9 , the slidable member on a mobile device  400  is not limited to being a slidable lens cover, as it may be a slidable switch  450  or the like. Moving the slidable switch  450  may open an application where a new position of a microphone  410  (after sliding) improves quality of the captured audio. In doing so, the actual position of the microphone  410  may not change. Moving the slidable switch  450  may open and cover ports  420  through which sound can be transmitted, such ports  420  connecting the microphone  450  to the environment  460  outside the mobile device  400 . 
     Referring now to  FIG. 10 , in some exemplary embodiments of a mobile device  500 , it may be possible to move the apparent location of a video sensor  510  upon manipulation of a slidable cover  550  without moving the video sensor  510  itself. For example, moving the apparent location of the video sensor  510  (when the video sensor  510  is a camera lens) may be beneficial when depth maps are created with two cameras. If one of the cameras can be moved, then the apparent distance (which determines the optimum range for depth map calculation) between the two cameras is changed, and the depth maps can be made to work for a larger range of depths. However, this is not limited to an arrangement using two cameras, as it is possible to take two consecutive pictures with a single camera such that the apparent position of the camera is changed between the two pictures. If the two consecutive pictures are taken in quick succession from the same camera with a small but minimal movement of the camera, a depth map may then be calculated from the two pictures. 
     In any of the exemplary embodiments disclosed herein, a user may be notified to change microphone locations to achieve optimal performance. For example, if a device is oriented in a landscape mode and is in an open position or is on a table in a closed position, then the microphones of the device are likely in suboptimal positions. Device orientation can be detected using accelerometers inside the device. In such embodiments, the device notifies the user of a need to slide the device open or closed for optimal performance. This can be performed by a number of different methods. For example, the device may show a video or moving graphic of a cover sliding to an open position or to a closed position; the device may play a sound that corresponds to a sound that comes from opening or closing the cover; the device may show a text such as “please open/close cover”; or the device may provide an audio instruction such as “please open/close cover.” Another method may be such that if audio is monitored during a video capture (e.g., from headphones or the like), the device could exaggerate a low quality audio signal caused by the moving parts of the device being in suboptimal positions for the current audio recording use case. For example, if the current position of the microphones causes the stereo image to be very narrow, the device could play back the audio signal to the monitoring headphones in mono and switch back to stereo once the microphone positions are changed to the optimal position. Still another method may be to show a red light next to a microphone that is in a suboptimal position. The light gradually turns green when the moving part with the microphone is moved to the optimal position. Combinations of the foregoing methods are also possible. 
     To improve suboptimal microphone locations, in some cases the user may choose to ignore the prompting to slide the cover open or closed. In this case, the device operates under the existing parameters. For example, if the height h of the triangle in  FIGS. 1-3  is too small, the device can either switch to recording stereo instead of multichannel 5.1 audio or binaural sound; the angle of the arriving sound (in Equation (7) above) can always be chosen to be positive, indicating that all directional sounds are rendered from the front of the device; or the device can record stereo but can use a blind surround upmixing algorithm (e.g., DOLBY PROLOGIC or the like) to create multichannel 5.1 audio from the stereo. 
     In other efforts to improve suboptimal microphone locations, adaptations may be made when the microphone locations are constantly changing. In bendable products such as a bendable mobile phone, the microphone locations with respect to each other may change continuously. With such devices the parameters d and h in the above equations are constantly updated. For example, the bendable mobile phone may calculate new d and h values for the multichannel 5.1 audio or binaural capture algorithm once for every window. These values are used for that window only and the next window may have different values. 
     Information regarding the directions of the sound sources may be used for applications other than multichannel 5.1 audio capture or binaural audio capture. For example, sound directions may be used in the control of games. 
     In any of the exemplary embodiments described above, it is possible to use a mobile device for audio recording in more orientations without incorporating additional microphones. 
     Referring now to  FIG. 11 , one exemplary method of optimizing audio capture parameters in real time for a mobile device is designated generally by the reference number  1100  and is hereinafter referred to as “method  1100 .” In the method  1100 , input is designated regarding either a purely audio capture or a combination of audio and video capture. This input is embodied in an input step  1110 . An analysis step  1120  is then executed in which directional analysis is performed to determine the optimal positions for microphones. The analysis step  1120  is carried out by a controller  1122  having a memory  1124  and a processor  1126 . Feedback regarding optimal positions for the microphone(s) is then provided in a feedback step  1130 . The feedback may comprise instructions to the user as to whether a slidable cover should be open or closed, whether the mobile device should be arranged in a landscape or portrait orientation, and/or the like. Audio capture is then carried out in an audio capture step  1140 . 
     An apparatus comprises at least one processor, and at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to: provide an audio capture event wherein one or more microphone configurations are configured to provide one or more audio signals based on at least one acoustic signal from at least one acoustic source, at least one of the one or more microphone configurations being defined by a first position of a first microphone configuration on a first portion and a second position of a second microphone configuration on a second portion, the second portion being movable relative to the first portion. The apparatus may be further caused to determine an optimal microphone configuration for the audio capture event using a directional analysis based on a correlation between audio channels defined by the first position of the first microphone configuration and the second position of the second microphone configuration. The apparatus may be further caused to provide a feedback regarding optimal positions for the first microphone configuration and the second microphone configuration for subsequent adjustment of the positions of the first microphone configuration and the second microphone configuration. The apparatus may be further caused to determine relative positions of the first microphone configuration and the second microphone configuration and configure the first microphone configuration and the second microphone configuration for optimal performance. The apparatus may be further caused to provide an indication to a user for the user to configure the first microphone configuration and the second microphone configuration for optimal performance. The second portion may be a cover, a slidable cover, a foldable portion, or a bendable portion of the apparatus. The first portion may include a camera and the second portion may be a slidable lens cover. The apparatus may further comprise a third microphone configuration. When the apparatus is positioned flat, a vertical plane through the first microphone configuration, the second microphone configuration, and the third microphone configuration may define a horizontal distance of zero between the first microphone configuration and the second microphone configuration when the apparatus is in the first position, and an optimal position for the audio capture event may comprise a horizontal non-zero distance between the first microphone configuration and the second microphone configuration when the apparatus is in the second position. The first microphone configuration and the second microphone configuration may comprise directional microphones. At least one of the first and second microphone configurations may comprise at least one of a microphone, one or more sound channels, and one or more sound inlets through which sound can be transmitted, the microphone being acoustically coupled to the one or more sound channels and the one or more sound inlets. At least one of the first and second microphone configurations may be modified by the movement of the second portion relative to the first portion. An electronic mobile device may comprise the apparatus. 
     A method comprises providing an audio capture event wherein one or more microphone configurations are configured to provide one or more audio signals based on at least one acoustic signal from at least one acoustic source, at least one of the one or more microphone configurations being defined by a first position of a first microphone configuration on a first portion and a second position of a second microphone configuration on a second portion, the second portion being movable relative to the first portion. The method may further comprise determining an optimal microphone configuration for the audio capture event using a directional analysis based on a correlation between audio channels defined by the first position of the first microphone configuration and the second position of the second microphone configuration. Using a directional analysis may further comprise transforming a plurality of input channels to a frequency domain using discrete Fourier transform. The method may further comprise dividing the frequency domain into subbands. The method may further comprise providing a feedback regarding optimal positions for the first microphone configuration and the second microphone configuration for subsequent adjustment of the first position of the first microphone configuration and the second position of the second microphone configuration. The method may further comprise determining relative positions of the first microphone configuration and the second microphone configuration and configuring the first and second microphone configurations for optimal performance. An indication may be provided to a user for the user to configure the microphone configurations for optimal performance. The microphone configuration may be further defined by a third microphone configuration on the first portion or the second portion. Providing a feedback regarding optimal positions for the plurality of microphones may comprise one or more of exaggerating a low quality audio output to the user, illuminating a light, providing a text graphic, and providing an audio instruction. 
     In a non-transitory computer readable storage medium encoded with instructions that, if executed by a computer, perform a process, the process comprises providing an audio capture event wherein one or more microphone configurations are configured to provide one or more audio signals based on at least one acoustic signal from at least one acoustic source, at least one of the one or more microphone configurations being defined by a first position of a first microphone configuration on a first portion and a second microphone configuration on a second portion, the second portion being movable relative to the first portion between the first position and a second position. 
     It should be understood that the foregoing description is only illustrative. Various alternatives and modifications can be devised by those skilled in the art. For example, features recited in the various dependent claims could be combined with each other in any suitable combination(s). In addition, features from different embodiments described above could be selectively combined into a new embodiment. Accordingly, the description is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.