Patent Publication Number: US-11380313-B2

Title: Voice-based control in a media system or other voice-controllable sound generating system

Description:
RELATED PATENT APPLICATION 
     This application is a Continuation of U.S. Non-Provisional patent application Ser. No. 15/962,011, filed on Apr. 25, 2018, and claims priority to commonly owned U.S. Provisional Patent Application No. 62/491,018 filed Apr. 27, 2017, which are hereby incorporated by reference in their entirety for all purposes. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to voice control of a system or device, and more particularly, for improved voice control of a system or device that generates sounds. 
     BACKGROUND 
     A growing number of systems are configured for voice-based control, or voice command, of one or more aspects of such systems. These systems may be referred to voice-controllable systems. A voice-controllable system may allow a user to easily control aspects of the system operation in a hands-free manner. Some example voice-controllable systems include home appliances, mobile phones (e.g., for voice-based dialing, texting, web browsing, etc.), media systems (e.g., TV, stereos, etc.), computer operating systems, commercial software for computers, internet search engines, vehicles, and call centers. Voice control has improved in recent years due to substantial advancements in voice recognition, e.g., based on the advancement of deep learning generated algorithms and the development of graphics processing units (GPUs) that allow accelerated processing of voice recognition algorithms. 
     However, for voice-controllable systems that also generate sound, such as certain TVs and other entertainment systems, mobile phone, computers, blue tooth speakers, etc., referred to herein as voice-controllable sound generating systems (SGS), the effectiveness of the voice-recognition system may be lessened by the fact that audio output by the voice-controllable SGS mixes with voice command audio, and may thus mask or make the voice audio difficult to identify. 
     SUMMARY 
     Embodiments of the present disclosure provide systems and methods for improving voice-based control of a voice-controllable sound generating system (SGS) by cancelling or otherwise countering sounds output by a sound source associated with the voice-controllable sound generating system. As used herein, a voice-controllable sound generating system includes any system that (a) generates sounds and (b) is configured for voice-based control of one or more functions of the system. Example voice-controllable sound generating systems include certain entertainment or media systems (e.g., a voice-controllable TV, stereo system, smartphone, laptop computer, tablet computer, desktop computer, etc.), blue tooth speakers, intercom systems, etc. 
     Some embodiments provide an audio countering system configured to obtain and use electronic system-based audio signals communicated by an audio source of the voice-controllable sound generating system to counter corresponding system-based audio signals received at a voice-control microphone, after being influenced by the surrounding physical environment and/or other distortion factors. By cancelling or countering the audio output by the sound generating system and received at the microphone, the audio countering system can effectively isolate or enhance a voice-based signal received at the microphone simultaneous with the sounds waves output by the sound generating system. A voice control system may then analyze the resulting audio signals, with the enhanced voice-based signal (resulting from the cancellation/countering of the sound generating system audio) to identify voice commands for the voice-controllable sound generating system, which may then be implemented. 
     In one embodiment, the system may use the same digital source to null, counterbalance, cancel, or compensate for the microphone to the sounds generated by the device. This may be performed in the digital domain. Furthermore, the system may compensate for system volume, speaker aberrations or anomalies, proximity to speaker, reflections, or echoes. In another embodiment, the system may use the digital source to compensate in the analog domain. For example, the digital source may be converted from analog to digital, the phase inversion may be matched, and gain or attenuation may be applied. In yet another embodiment, an analog source could be converted to the digital domain and compensated-for in the digital domain. In still yet another embodiment, an analog source could be used by matched phase inversion and attenuated or gain applied as-needed. 
     The system may include a digital or analog sound source. The output of the sound source may be amplified with a specified gain to the speaker. In parallel, the output of the sound source may be routed to a digital or analog compensation circuit. The compensation circuit may also have input from a system microphone, into which voice-activated commands are entered. The compensation circuit may perform, in the digital or analog domain as described above, compensation for the output of the sound source in the input from the microphone. A delay may be accounted-for, wherein the sound source may have taken an amount of time to reach the microphone after leaving the speaker. The compensated signal may be interpreted by the rest of the system, in which voice-activated commands are scanned-for and recognized. 
     In order to compensate for sound-making devices, the system may first perform a calibration mode. In the calibration mode, an available or desired audio frequency band sweep may be performed, wherein the sound source goes through such a sweep to determine ambient conditions of input for the microphone. Through such a process, expected delay, echo, and other signal aspects may be characterized. This characterization information may be used in subsequent operating modes to compensate-for the sound source during operation and detection of voice commands. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Example aspects of the present disclosure are described below in conjunction with the figures, in which: 
         FIG. 1  illustrates an example system for cancelling or otherwise countering the audio output by a voice-controllable sound generating system (e.g., a voice-controllable media system) to enhance the identification of voice commands from a user, according to embodiments of the present invention; 
         FIG. 2  illustrates an example sound compensation system for a digital voice-controllable sound generating system, with synchronization signaling, according to one embodiment; 
         FIG. 3  illustrates an example sound compensation system for a digital voice-controllable sound generating system, without synchronization signaling, according to one embodiment; 
         FIG. 4  illustrates an example sound compensation system for an analog voice-controllable sound generating system, according to one embodiment; 
         FIG. 5  illustrates an example system for synchronizing sound cancelling/countering signals for an analog voice-controllable sound generating system, according to one embodiment; and 
         FIG. 6  illustrates an example method for calibrating a sound compensation system to compensate for acoustic distortion factors, according to one embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present disclosure provide systems and methods for improving voice-based control of a voice-controllable sound generating system (e.g., a voice-controllable entertainment system, TV, stereo system, smartphone, computer, blue tooth speaker, intercom system, etc.) by cancelling or otherwise countering sounds output by a sound source associated with the voice-controllable sound generating system. 
     A voice-controllable sound generating system may include a sound generating system (SGS) audio source that generates and/or communicates Electronic SGS audio signals for output by speaker(s) as sound waves, and a voice-control microphone intended to receive voice-based audio including voice commands for controlling various functions of the sound generating system (e.g., power, operating mode, volume, channel, media playback functions, system settings, etc.). However, the voice-control microphone may also inherently receive SGS-based sound waves output by the speaker(s) and/or additional sound waves from other sources, which may distort or conceal the voice audio and thus complicate the accurate identification of the voice commands from the audio received at the microphone. 
     Thus, some embodiments provide an audio countering system configured to obtain and use the Electronic SGS audio signals communicated by the SGS audio source (the same electronic audio signals that are communicated to and output by the speakers as SGS-based sound waves) to counter the SGS-based audio received at the voice-control microphone (after being influenced by the surrounding physical environment and/or other distortion factors). For example, the audio countering system may use the electronic SGS audio signals to generate SGS audio-countering signals calculated to cancel or otherwise counter the SGS-based audio received via the microphone. By cancelling or countering the SGS-based audio received via the microphone, the audio countering system can effectively isolate or enhance a voice-based audio signal from a combined audio signal—including the voice-based audio signal and the SGS-based audio-received at the microphone. The audio countering system can then communicate the SGS audio-countered audio signal (including the isolated or enhanced voice-based audio signal) to a voice control system, which may identify voice commands from the SGS audio-countered audio signal, and implement the control functions associated with the identified voice commands. 
     The audio countering system may be integrated in or separate from the sound generating system, according to the particular embodiment. 
     Some embodiments include a calibration system configured to modify (calibrate) the Electronic SGS audio signals used by the audio countering system to cancel or otherwise counter the SGS-based audio received via the microphone, in particular to account for the influence of distortion factors on the SGS-based audio, e.g., time delay and signal distortion caused by the transmission, reflection, absorption, diffusion, etc. of sound waves. Distortion factors are discussed in more detail below with reference to  FIG. 1 . 
     The calibration system may be configured to output calibration audio signals via one or more speakers, receive calibration sound waves via the microphone, and determine calibration data that characterizes the influence of distortion factors on the calibration audio signals. The audio countering system may use the calibration data for countering SGS-based audio signals output via speakers and received at the voice-control microphone, in particular to compensate for distortion factors that influence the SGS-based audio signals. 
     The calibration audio source may be the SGS audio source or a separate calibration audio source. Further, the calibration audio signals may comprise portion(s) of the SGS-based audio signals generated by the SGS audio source, or may be integrated in or combined with SGS-based audio signals generated by the SGS audio source, or may be output separate from the output of SGS-based audio signals (e.g., during a defined calibration process), or otherwise generated and output. 
     Other embodiments may omit the calibration system. 
     Various embodiments may be configured for one or more of the following types of sound countering: 
     1. “Digital-digital sound-countering”: Digital countering of digital signals. For example, using electronic SGS-based audio signals generated by a digital SGS audio source to counter digital SGS-based audio signals (e.g., audio signals received at a voice-control microphone and passed through an analog-to-digital (ADC) converter). 
     2. “Digital-analog sound-countering”: Digital countering of analog signals. For example, using electronic SGS-based audio signals generated by a digital SGS audio source to counter analog SGS-based audio signals received at a voice-control microphone. 
     3. “Analog-analog sound-countering”: Analog countering of analog signals. For example, using electronic SGS-based audio signals generated by an analog SGS audio source to counter analog SGS-based audio signals received at a voice-control microphone. 
     4. “Analog-digital sound-countering”: Analog countering of digital signals. For example, using electronic SGS-based audio signals generated by an analog SGS audio source to counter digital SGS-based audio signals (e.g., audio signals received at a voice-control microphone and passed through an analog-to-digital (ADC) converter). 
       FIG. 1  illustrates an example system  10  for cancelling or otherwise countering the audio output by a voice-controllable sound generating system (e.g., a voice-controlled media system) to enhance the identification of voice commands from a user, according to embodiments of the present invention. The voice-controllable sound generating system (SGS) may comprise a TV, a stereo system, a smartphone, laptop computer, tablet computer, desktop computer, or any other system configured to output SGS-based sounds, receive voice-based commands (e.g., via a microphone), and control one or more aspects of the voice-controllable sound generating system based on the voice-based commands. 
     As shown in  FIG. 1 , example system  10  may include a sound generating system (SGS) audio source  12 , one or more speakers  14 , a microphone  16 , a calibration system  20 , an audio countering system  22 , and a voice control system  24 . SGS audio source may comprise any circuits and other electronics configured to communicate Electronic SGS audio signals  30  (analog or digital) to one or more speakers  14 , which may output the signals  30  as SGS-based sound waves (e.g., into a room or an outdoor environment). In some embodiments, SGS audio source may generate and communicate the Electronic SGS audio signals  30  (analog or digital) for output by speaker(s)  14  as SGS-based sound waves. In other embodiments, SGS audio source may act as a pass-through or relay to communicate Electronic SGS audio signals  30  received from another source to speaker(s)  14 . 
     The SGS-based sound waves output by speaker(s)  14  may be received by microphone  16 , converted to electronic signals (analog or digital), and communicated to audio countering system  22 . The SGS-based audio signals may be influenced by one or more distortion factors  40  (e.g., sound wave reflections due to the respective room and/or other physical objects), as discussed below in more detail. Thus, the SGS-based electronic signals communicated by microphone  16  to audio countering system  22  are referred to as distorted SGS-based audio signals  32 . 
     Microphone  16  may receive sound waves from any number of audio sources, including SGS-based sound waves discussed above, voice-based sound waves (which may include voice commands) from one or more persons  60 , and/or other sound waves from other source(s). Microphone  16  may convert or otherwise process the combined audio signals to generate microphone-processed audio signals  36  (analog or digital), which may include (a) distorted SGS-based audio signals  32  corresponding with received SGS-based sound waves, and (b) additional audio signals  34  including voice-based signals corresponding with received voice-based sound waves and any other signals corresponding with sound waves received from any other source. 
     In some embodiments, in addition to communicating Electronic SGS audio signals  30  for output by speaker(s)  14  as sound waves, SGS audio source may also communicate the same Electronic SGS audio signals  30  to audio countering system  22 . Audio countering system  22  may use the Electronic SGS audio signals  30  received from SGS audio source to counter the distorted SGS-based audio signals  32  (based on the same Electronic SGS audio signals  30 ) received from microphone  16 , to thereby help isolate or enhance voice-based audio signals in the combined microphone-processed audio signals  36 . 
     Audio countering system  22  may include any circuits and/or other electronics configured to use Electronic SGS audio signals  30  received from SGS audio source to cancel or otherwise counter distorted SGS-based audio signals  32  received via microphone  16 , e.g., to improve the detection of human voice commands within the additional audio signals  34  received via microphone  16 . When a person speaks a voice command for a selected function associated with system  10  while speaker(s)  14  are outputting SGS-based sound waves, microphone  16  receives combined sound waves and generates a combined audio signal  36  including distorted SGS-based audio signals  32  combined with voice-based audio signals  34  and/or other audio signals. 
     Audio countering system  22  may use electronic SGS audio signals  30  (which may or may not be modified/calibrated based on calibration data  44  provided by a calibration system  20 , as discussed below) to counter the distorted SGS-based audio signals  32  within the combined audio signal  36  received from microphone  16 , to generate SGS-countered audio signals  38 , which may substantially isolate or enhance the voice-based audio signals (digital or analog) from the combined audio signal  36  received from microphone  16 . Audio countering system  22  may then communicate the SGS-countered audio signals  38  to voice control system  24 , which may analyze the signals  38  to identify one or more voice commands, and implement or communicate with a respective control system to implement the identified voice command(s) for selected function(s) associated with system  10 . 
     In some embodiments, audio countering system  22  may modify the Electronic SGS audio signals  30  received from SGS audio source based on calibration data  44  calculated by calibration system  20 , and use the modified (calibrated) Electronic SGS audio signals  46  to cancel or counter the distorted SGS-based audio signals  32  received via microphone  16 . For example, audio countering system  22  may use calibration data  44  calculated by calibration system  20  to calibrate the Electronic SGS audio signals  30  to better match the distorted SGS-based audio signals  32  to be countered. Thus, the calibration data  44  may be configured to account for the influence of distortion factors  40  on the SGS-based audio signals, e.g., at any point(s) along the course from the communication of the electronic SGS audio signals  30  from SGS audio source, through the transmission and detection of corresponding SGS-based sound waves (from the system speaker(s)  14 , through a physical environment, and to microphone  16 ), and to the communication of distorted SGS-based audio signals  32  to audio countering system  22  for processing. 
     Calibration system  20  may include a calibration audio source  21  configured to generate and output calibration audio signals  42  (analog or digital) to speaker(s)  14  for output as sound waves. The calibration sound waves may be received at microphone  16  and converted to distorted calibration audio signals  48  (analog or digital), which may be communicated to calibration system  20  for processing. Distorted calibration audio signals  48  represent calibration audio signals  42  after being influenced or “distorted” by distortion factors  40 . Calibration audio signals  42  may include any audio signals (human-audible or human-inaudible) that may be used for such system calibration. For example, calibration audio signals  42  may include white noise signals output at various volumes to define baseline compensation variables for spatial aberrations of the listening space and system performance. 
     Calibration system  20  may analyze the distorted calibration audio signals  48  (e.g., in comparison to the corresponding calibration audio signals  42 ) using any suitable algorithms to determine calibration data  44  that characterizes the influence of distortion factor(s)  40  on the calibration audio signals  42 . As discussed above, audio countering unit  22  may use the calibration data  44  for countering distorted SGS-based audio signals  32  communicated by microphone  16 . For example, audio countering unit  22  may apply the calibration data  44  to Electronic SGS audio signals  30  generated by SGS audio source to generate calibrated SGS-based audio signals  46  that may be are used to counter the distorted SGS-based audio signals  32  received from microphone  16 . 
     In some embodiments, calibration audio signals  42  may include sync signals, which may be used to measure the delay between (a) electronic SGS audio signals  30  being received at audio countering system  22  from SGS audio source  12  and (b) the resulting distorted SGS-based audio signals  32  received at audio countering system  22  via microphone  16 , such that the earlier-received electronic SGS audio signals  30  may be time-shifted by the appropriate time period for countering the later-received distorted SGS-based audio signals  32 . Synch signals  42  may include any sound signals, at any volume and frequency or frequencies (human-audible or human-inaudible) that can be detected by microphone  16  and identified by calibration system  20  or audio countering system  22 . In some embodiments, sync signals may be output using a spread-spectrum approach in the audio domain. 
     As used herein, “distortion factors” may include any factors that distort or otherwise influence any type of audio signals (e.g., SGS-based audio signals, calibration audio signals, etc.), while in the form of electronic signals (e.g., being communicated between different components of system  10 ) or in the form of sound waves (e.g., between being output by speaker(s) and being received at a microphone). For example, distortion factors may include transmission effects on audio signals from a respective sound source (e.g., SGS audio source or calibration audio source) to one or more speaker(s), effects imparted by the speaker(s) themselves, acoustic effects from the surrounding physical environment (e.g., walls, furniture, or other physical structures), acoustic effects from interaction between sound waves from multiple speakers, effects imparted by the microphone itself (e.g., associated with collection and/or processing of audio signals), and/or any other distortion factors that may impart an influence on the respective audio signals (e.g., SGS-based audio signals or calibration audio signals). 
     In other embodiments, audio countering system  22  is configured to cancel or counter the distorted SGS-based audio signals  32  without calibrating the Electronic SGS audio signals  30 , and may thus omit calibration system  20 . 
     In addition, audio countering system  22  may include any circuits and/or other electronics configured to provide any one or more of the following types of sound-countering defined above: (1) digital-digital sound-countering, (2) digital-analog sound-countering, (3) analog-analog sound-countering, and/or (4) analog-digital sound-countering. 
       FIG. 2  illustrates components of an example sound compensation system  10 A for a digital voice-controllable sound generating system (SGS), with synchronization signaling, according to one example embodiment of system  10  shown in  FIG. 1 . System  10 A may include a digital SGS audio source  12  configured to output digital SGS audio signals  30  for output via speaker(s)  14 , e.g., after passing through a digital-to-analog converter  80  and amplifier  82 . In addition, digital SGS audio source  12  may communicate the same digital SGS audio signals  30  to a digital audio countering system  22 A, which uses the SGS audio signals  30  to counter (distorted and time-shifted) audio signals received via microphone  16 , e.g., as discussed above regarding  FIG. 1 . 
     In some embodiments, the system may include multiple digital SGS audio sources simultaneously outputting different sounds. Thus, as shown in  FIG. 2 , at least one further digital SGS audio source  12 ′ may generate digital SGS audio signals for output via speaker(s)  14 ′, e.g., after passing through a digital-to-analog converter  80 ′ and amplifier  82 ′. In addition, each further digital SGS audio source  12 ′ may communicate its digital SGS audio signals to digital audio countering system  22 A, which may use the SGS audio signals from the multiple SGS audio sources  12 ,  12 ′ to counter audio signals received via microphone  16 . 
     System  10 A may include a calibration system  20  configured to generate and output synchronization or calibration signals  42 , e.g., at defined intervals or based on defined triggering events. In the illustrated example, calibration system  20  outputs synchronization (“sync”) signals  42  via the same speaker(s)  14  as the audio from digital SGS audio source  12 . Synch signals  42  may include any sound signals (within or outside the typical human-audible frequency spectrum) that can be detected by microphone  16  and identified by DSP  70 . 
     Digital audio countering system  22 A may include an amplifier  60 , an analog-to-digital converter (ADC)  62 , a digital signal processor (DSP)  70 , a memory buffer (e.g., RAM), and one or more compensation algorithms  50 , along with any other hardware and/or software/firmware components for performing sound countering functionality. DSP  70  may be configured to receive (a) digital SGS audio signals  30  from digital SGS audio source  12  (and/or at least one further digital SGS audio source  12 ′) and (b) microphone-processed audio signals  36  received via microphone  16 , e.g., after passing through amp  60  and ADC  62 . Microphone-processed audio signals  36  may include audio signals originating from various sources and distorted by various distortion factors  40 , as discussed above regarding  FIG. 1 . For example, microphone-processed audio signals  36  may include combination of (a) distorted SGS-based audio signals  32  corresponding with digital SGS audio signals  30 , (b) distorted sync signals  48  corresponding with synch signals  42 , and/or (c) additional audio signals  34  including voice-based sound signals. 
     DSP  70  may be configured to use digital SGS audio signals  30 , which may be time-shifted or synchronized based on received sync signals  48 , to counter the distorted SGS-based audio signals  32  within the combined audio signal  36  received from microphone  16 , to generate SGS-countered audio signals  38 , which may substantially isolate or enhance any voice-based audio signals received via microphone  16 . DSP  70  may be configured to execute any suitable audio compensation algorithms  50  for generating SGS-countered audio signals  38 . For example, DSP  70  may be configured to execute an adaptive filter according to any known or suitable active noise cancellation algorithms or routines, e.g., embodied as a known or suitable frequency-domain adaptive filter configured to efficiently process discrete-time signals using block and multi-rate adaptive filtering, e.g., as disclosed in the article “Frequency-domain and multirate adaptive filtering” by J. J. Shynk,  IEEE Signal Processing Magazine , Vol. 9, Issue 1, January 1992 (pp. 14-37). 
     In some embodiments, DSP  70  may utilize a memory buffer (e.g., RAM)  72  to temporarily store (buffer) digital SGS audio signals  30  from digital SGS audio source  12  (or multiple digital SGS audio sources  12 ,  12 ′), to use the digital SGS audio signals  30  for countering the corresponding distorted and time-shifted (delayed) SGS-based audio signals  32  received via microphone  16 . DSP  70  may determine the appropriate duration for time-shifting the (earlier-received) digital SGS audio signals  30  to counter the corresponding (later-received) distorted SGS-based audio signals  32  based on the timing of distorted sync signals  48  received from microphone  16  and clock-based timing of the output of synch signals  42  from calibration system  20 . System  10 A may recalibrate this time-shifting delay at any suitable interval or upon any defined triggering event). 
       FIG. 3  illustrates components of an example sound compensation system  10 B for a digital voice-controllable sound generating system, without synchronization signaling, according to one example embodiment of system  10  shown in  FIG. 1 . 
     System  10 B may be generally similar to system  10 A shown in  FIG. 2 , but may be configured to synchronize the use of digital SGS audio signals  30  received from SGS audio source  30  to counter the resulting (later-received) distorted SGS-based audio signals  32  without the use of discrete sync signals  42 . 
     In some embodiments, the digital audio countering system  22 B of system  10 B may include (a) a first memory buffer (e.g., RAM)  72  for storing or buffering digital SGS audio signals  30  from digital SGS audio source  12  (or multiple digital SGS audio sources  12 ,  12 ′) and a second memory buffer (e.g., RAM)  74  for storing or buffering SGS-based audio signals  32  received via microphone  16 . DSP  70  may analyze the details of the respective audio signals stored in buffers  72  and  74  to identify elements of distorted SGS-based audio signals  32  that match the corresponding digital SGS audio signals  30 , and determine the associated delay between the two signals based on the identified matching signal elements. DSP  70  may then use this determined delay to time-shift digital SGS audio signals  30  to counter the corresponding (later-received) distorted SGS-based audio signals  32 . System  10 A may perform such time-shift calibration continuously, or at any suitable interval, or upon any defined triggering event. 
       FIG. 4  illustrates components of an example sound compensation system  10 C for an analog voice-controllable sound generating system, according to one example embodiment of system  10  shown in  FIG. 1 . System  10 C may include an analog SGS audio source  12  configured to output analog SGS audio signals  30  for output via speaker(s)  14 , e.g., after passing through an amplifier  82 . In addition, analog SGS audio source  12  may communicate the same analog SGS audio signals  30  to an analog audio countering system  22 C, which uses the analog SGS audio signals  30  to counter (distorted and time-shifted) analog audio signals received via microphone  16 , e.g., as discussed above regarding  FIG. 1 . 
     System  10 C may include a calibration system  20  configured to generate and output synchronization or calibration signals  42 , e.g., at defined intervals or based on defined triggering events. In the illustrated example, calibration system  20  outputs synchronization (“sync”) signals  42  via the same speaker(s)  14  as the audio from analog SGS audio source  12 . Synch signals  42  may include any sound signals (within or outside the typical human-audible frequency spectrum) that can be detected by microphone  16  and identified by DSP  70 . 
     Analog audio countering system  22 C may include an amplifier  60  and an analog compensation circuit  90 . Analog audio countering system  22 C may be configured to receive (a) analog SGS audio signals  30  from analog SGS audio source  12  and (b) analog microphone-processed audio signals  36  received via microphone  16 , e.g., after passing through amplifier  60 . Microphone-processed audio signals  36  may include audio signals originating from various sources and distorted by various distortion factors  40 , as discussed above regarding  FIG. 1 . For example, microphone-processed audio signals  36  may include combination of (a) distorted SGS-based audio signals  32  corresponding with analog SGS audio signals  30 , (b) distorted sync signals  48  corresponding with synch signals  42 , and/or (c) additional audio signals  34  including voice-based sound signals. 
     Analog audio countering system  22 C may use analog SGS audio signals  30 , which may be time-shifted or synchronized based on received sync signals  48 , to counter the distorted SGS-based audio signals  32  within the combined audio signal  36  received from microphone  16 , to generate SGS-countered audio signals  38 , which may substantially isolate or enhance any voice-based audio signals received via microphone  16 . Analog compensation circuit  90  may include any suitable delay/synchronization circuitry for time-shifting (delaying) the application of analog SGS audio signals  30  received from analog SGS sound source  12  to cancel/counter the corresponding (later-received) distorted SGS-based audio signals  32  received via microphone  16 , e.g., using a time delay based on the determined delay between sync signals  42  generated by calibration source  20  and the resulting distorted sync signals  48  received via microphone  16 . 
       FIG. 5  illustrates an example system  100  for synchronizing sound cancelling/countering signals for an analog voice-controllable sound generating system, e.g., for use in system  10 C shown in  FIG. 4 , according to one embodiment. System  100  may include the previously discussed components of microphone  16 , amplifier  60 , and analog SGS audio source  12 , along with spatial aberration correction electronics  102 , PLL (phase locked loop) and AGC (acoustic gain control) electronics  104 , phase shift adjust and AGC electronics  106 , and an audio sum amplifier  108 . 
     As shown in  FIG. 5 , analog SGS audio source  12  outputs analog SGS audio signals to both (a) speaker(s)  14  and (b) the sound countering system, in particular to (i) phase shift adjust and AGC electronics  106  and (ii) PLL and AGC electronics  104 . Microphone  16  receives sound waves (originated from the SGS audio signals, any voice-based signals, and/or other audio sources) and generate corresponding analog audio signals, which are passed through amplifier  60  and then processed by spatial aberration correction electronics  102 . The spatial-aberration-corrected signals are then passed to both (a) PLL and AGC electronics  104  and (b) audio sum amplifier  108 . 
     As shown, PLL and AGC electronics  104  receives (a) analog SGS audio signals from analog SGS audio source  12  and (b) microphone-received and spatial-aberration-corrected signals from spatial aberration correction electronics  102 , and process such signals to generate phase error voltage and gain adjust signals  105 , which are passed to phase shift adjust and AGC electronics  106 . Phase shift adjust and AGC electronics  106  phase-shifts the analog SGS audio signals received from analog SGS audio source  12  based on the phase error voltage and gain adjust signals  105  received from PLL and AGC electronics  104 , and forwards the phase-shifted SGS audio signals to audio sum amplifier  108 . 
     Audio sum amplifier  108  sums (a) the microphone-received signals received from spatial aberration correction electronics  102  with (b) the phase-shifted SGS audio signals received from phase shift adjust and AGC electronics  106 , which cancels or counters the portion of the microphone-received signals corresponding with the SGS audio signals output via speaker(s)  14  and received via microphone  16 , to thereby enhance the remaining portions of the microphone-received signals, e.g., including voice-based signals. Thus, the resulting SGS-countered audio signals  38  may enhance any voice commands included in the microphone-received signals, and these enhanced signals  38  may then be passed to a voice control system  24  for processing. 
     In some embodiments, a synchronization signal can be used to create the PPL error voltage and gain control signals  105 . For example, analog SGS audio source  12  may include a synchronization signals generator  120  configured to generate and output synchronizations signals. Further, in some embodiments, the spatial aberration correction electronics  102  may be omitted, thus providing a fully analog system. 
       FIG. 6  illustrates an example method  200  for calibrating a sound compensation system to compensate for acoustic distortion factors, according to one embodiment. In some embodiments, method  200  may be implemented by calibration system  20  shown in  FIGS. 1-3 , for example. With reference to  FIG. 1 , at  202  calibration system  20  may output calibration signals  42  via speaker(s)  14  at a first (e.g., low) volume. In one embodiment the calibration signals  42  may comprise white noise signals. At  204 , calibration system  20  may receive and analyze distorted calibration audio signals  48  via microphone  16  and determine compensation values representing the distortion of the received audio signals, e.g., as imparted by any distortion factors  40 . 
     At  206 , calibration system  20  may determine whether a predefined maximum volume for the calibration signals has been reached. If not, as indicated at  208 , calibration system  20  may output calibration signals  42  via speaker(s)  14  at a next (e.g., higher) volume level, and determine resulting compensation values based on distorted calibration audio signals  48  received via microphone  16 . When calibration system  20  determines at  206  that the predefined maximum volume for the calibration signals has been reached, all compensation values are acquired and the method may end, as indicated at  210 .