PATENT DOCUMENT

Publication Number: US-9706288-B2
Application Number: US-201514656443-A
Country: US
Kind Code: B2

Title: Apparatus and method of active noise cancellation in a personal listening device

Abstract:
Personal listening device (PLD) includes earphone housing having therein (a) inertial sensor to detect motion of PLD and to generate motion signal, (b) pressure sensor to detect compression of portion of PLD and to generate pressure sensor signal, and (c) speaker to receive anti-noise signal and desired audio signal from electronic device, and active noise control (ANC) system to generate anti-noise signal as being one of first or second anti-noise signal. ANC system includes processor, vibration detector to detect vibration of the PLD based on at least one of motion signal or pressure sensor signal, and ANC anti-noise generator to generate first anti-noise signal when vibrations are not detected by vibration detector, and to generate second anti-noise signal when vibrations are detected by vibration detector. Second anti-noise signal is based on detected vibrations. Processor reconfigures ANC system for ANC anti-noise generator to generate second anti-noise signal. Other embodiments are described.

Claims:
The invention claimed is: 
     
       1. A personal listening device (PLD) comprising:
 an earphone housing having therein (a) an inertial sensor to detect motion of the PLD and to generate a motion signal, (b) a pressure sensor to detect compression of a portion of the PLD and to generate pressure sensor signal, and (c) a speaker to receive an anti-noise signal and a desired audio signal from an electronic device; and 
 an active noise control (ANC) system to generate the anti-noise signal as being one of a first anti-noise signal or a second anti-noise signal, the ANC system includes
 a processor, 
 a vibration detector coupled to the processor, the vibration detector to detect a vibration of the PLD based on at least one of the motion signal or the pressure sensor signal, and 
 an ANC anti-noise generator coupled to the processor, the ANC anti-noise generator to generate the first anti-noise signal when vibrations are not detected by the vibration detector, and to generate the second anti-noise signal when vibrations are detected by the vibration detector, the second anti-noise signal being based on detected vibrations, 
 wherein the processor reconfigures the ANC system for the ANC anti-noise generator to generate the second anti-noise signal. 
 
 
     
     
       2. The PLD in  claim 1 , wherein the inertial sensor comprises at least one of an accelerometer, a gyroscope, or a microelectromechanical system (MEMS), wherein the inertial sensor detects motion in at least three axes: x-axis, y-axis, z-axis. 
     
     
       3. The PLD in  claim 1 , wherein the first anti-noise signal is based on at least one of a reference microphone signal or an error microphone signal. 
     
     
       4. The PLD in  claim 3 , wherein the ANC system comprises a memory device:
 to store a plurality of predetermined sensor data patterns including patterns that indicate the contexts of: walking, jumping, running, and vehicle motions or vibrations. 
 
     
     
       5. The PLD in  claim 4 , wherein the vibration detector is coupled to the memory device and wherein the vibration detector to detect the vibration comprises:
 the vibration detector matching at least one of the motion signal or the pressure sensor signal with at least one of the predetermined sensor data patterns. 
 
     
     
       6. The PLD of  claim 5 , wherein the processor reconfiguring the ANC system comprises:
 the processor locking filter coefficients of an adaptive filter included in the ANC system or locking filtering by the adaptive filter included in the ANC system. 
 
     
     
       7. The PLD of  claim 5 , wherein the processor reconfiguring the ANC system comprises:
 the processor changing a speed of updates made to an adaptive filter by an adaptive filter controller included in the ANC system. 
 
     
     
       8. The PLD of  claim 5 , wherein the processor reconfiguring the ANC system comprises:
 the processor selecting predetermined adaptive filter coefficients associated with the at least one of the predetermined sensor data patterns, wherein the predetermined coefficients are stored in the memory device, and 
 the processor overriding filter coefficients of an adaptive filter, that were computed by an adaptive filter controller included in the ANC system, with the predetermined filter coefficients. 
 
     
     
       9. The PLD of  claim 5 , wherein the processor reconfiguring the ANC system comprises:
 the processor applying a jacket on filter coefficients of an adaptive filter included in the ANC system. 
 
     
     
       10. The PLD of  claim 5 , wherein the processor reconfiguring the ANC system comprises:
 the processor muting the anti-noise signal output from the speaker. 
 
     
     
       11. A method of active noise cancellation in a personal listening device (PLD) comprising:
 receiving by an active noise control (ANC) system a reference microphone acoustic signal and an error microphone acoustic signal from the PLD; 
 receiving by the ANC system at least one of a motion signal or a pressure sensor signal from the PLD, wherein the motion signal is based on a detected motion of the PLD and the pressure sensor signal is based on a detected compression of a portion of the PLD; 
 determining by the ANC system whether vibrations of the PLD are detected based on at least one of the motion signal or the pressure sensor signal; 
 when vibrations are not detected, generating by the ANC system a first anti-noise signal based on the reference microphone acoustic signal and the error microphone acoustic signal; and 
 when vibrations are detected, generating by the ANC system a second anti-noise signal, wherein generating by the ANC system the second anti-noise signal includes reconfiguring the ANC system. 
 
     
     
       12. The method of  claim 11 , wherein determining by the ANC system whether vibrations of the PLD system are detected comprises:
 the ANC system matching at least one of the motion signal or the pressure sensor signal with at least one of a plurality of predetermined sensor data patterns. 
 
     
     
       13. The method of  claim 12 , wherein the plurality of predetermined sensor data patterns are stored in a memory device included in the ANC system. 
     
     
       14. The method of  claim 13 , wherein the plurality of predetermined sensor data patterns include patterns that indicate the contexts of walking, jumping, running, and vehicle motions or vibrations. 
     
     
       15. The method of  claim 14 , wherein reconfiguring the ANC system comprises:
 locking filter coefficients of an adaptive filter included in the ANC system. 
 
     
     
       16. The method of  claim 14 , wherein reconfiguring the ANC system comprises:
 changing a speed of updates made to an adaptive filter by an adaptive filter controller included in the ANC system. 
 
     
     
       17. The method of  claim 14 , wherein reconfiguring the ANC system comprises:
 selecting predetermined adaptive filter coefficients associated with the at least one of the predetermined sensor data patterns, wherein the predetermined coefficients are stored in the memory device, and 
 a processor overriding filter coefficients of an adaptive filter, that were computed by an adaptive filter controller included in the ANC system, with the predetermined filter coefficients. 
 
     
     
       18. The method of  claim 14 , wherein reconfiguring the ANC system comprises:
 a processor applying a jacket on filter coefficients of an adaptive filter included in the ANC system. 
 
     
     
       19. A computer-readable non-transitory storage medium having stored therein instructions, when executed by a processor, causes an active noise control (ANC) system to perform a method of active noise cancellation in a personal listening device (PLD), the method comprising: receiving a reference microphone acoustic signal and an error microphone acoustic signal from the PLD; receiving at least one of a motion signal or a pressure sensor signal from the PLD, wherein the motion signal is based on a detected motion of the PLD and the pressure sensor signal is based on a detected compression of a portion of the PLD; determining whether vibrations of the PLD are detected based on at least one of the motion signal or the pressure sensor signal; when vibrations are not detected, generating a first anti-noise signal based on the reference microphone acoustic signal and the error microphone acoustic signal; and when vibrations are detected, generating a second anti-noise signal, wherein the processor reconfigures the ANC system to generate the second anti-noise signal. 
     
     
       20. The computer-readable non-transitory storage medium of  claim 19 , wherein the ANC system is included in an electronic device coupled to the PDL, the electronic device transmitting an audio signal to the PDL. 
     
     
       21. The computer-readable non-transitory storage medium of  claim 19 , wherein the ANC system is included in the PDL.

Description:
FIELD 
     Embodiments of the invention relate generally to an apparatus and a method that improve the active noise control (ANC) in a personal listening device (PLD) by reducing artifacts generated by the ANC system in the noise-cancelling control signal when vibrations of the personal listening device are detected. More specifically, an embodiment of the invention is directed to a personal listening device having an active noise control (ANC) system that detects vibrations of the personal listening device and reduces the artifacts generated by the ANC system by reconfiguring the ANC system to generate an anti-noise signal that is based on the detected vibration. 
     BACKGROUND 
     Currently, some personal listening devices such as earbuds, earphones, and headphones include an active noise control (ANC), also referred to as acoustic noise cancellation, system that improves the listening experience for the user by cancelling the external or ambient (environmental) noises from being heard by the user. The ANC technique cancels the external or ambient sound by generating a control signal that causes the personal listening device to introduce an anti-noise, which is an additional, electronically controlled sound field designed to counteract or destructively interfere with the desired external or ambient sound. 
     In some ANC systems, a reference microphone included in the personal listening device (PLD) may be used to pick up the primary noise source and to generate a reference signal. In some ANC systems, an error microphone also coupled to the personal listening device (PLD) may be used to detect the unwanted noise being heard by the user and to generate an error signal that represents the residual noise that may still remain despite the ANC system being in operation. The error signal monitors the ANC system&#39;s performance. The reference signal and the error signal may then be used to control the adaptation of the filters in the ANC system. 
     However, personal listening devices that perform ANC often have issues performing the ANC in a stable manner. For instance, when using the personal listening device while walking, running, or being on a slightly rough bus ride, the sound field captured by the reference microphone and the error microphone may vary substantially from the unwanted ambient noise that is to be cancelled. As a result, the adaptive filters converge to a wrong solution and the anti-noise being generated in accordance with this incorrect solution may include audible artifacts that can be significant enough to cause the user to feel uncomfortable or even nauseous. 
     SUMMARY 
     Generally, the invention relates to personal listening devices such as headphones (e.g., earphones, earbuds) that are part of an active noise control (ANC) system to generate an acoustic anti-noise signal that is driving a speaker in the headphone. Specifically, an embodiment of the invention pertains to improving the ANC of the personal listening devices by using signals from an accelerometer and/or signals from a pressure sensor included in the personal listening device (e.g., within an earphone housing) to detect vibrations in the personal listening device and adapting the ANC system to generate an anti-noise signal based on the detected vibrations. 
     In one embodiment of the invention, a personal listening device (PLD) includes an earphone/headphone housing having therein a speaker, an error microphone, an inertial sensor, and a pressure sensor. The PLD also includes an active noise control (ANC) system. The inertial sensor may detect motion of the PLD and generate a motion signal. The pressure sensor may detect compression of a portion of the PLD and generate pressure sensor signal. The speaker may receive an anti-noise signal and a desired audio signal from an electronic device. The ANC system may generate one of a first anti-noise signal or a second anti-noise signal to drive the speaker and hence, reduce the ambient sound that may be heard by a user of the PLD. The ANC system may include a processor, a vibration detector to detect a vibration of the PLD based on at least one of the motion signal or the pressure sensor signal, and an ANC adaptive anti-noise generator. The ANC adaptive anti-noise generator may generate the first anti-noise signal when vibrations are not detected. The ANC system may generate, when vibrations are detected, the second anti-noise signal based on detected vibrations. In one embodiment, the processor reconfigures the ANC system for the ANC anti-noise generator to generate the second anti-noise. 
     In another embodiment of the invention, a method of active noise cancellation in a PLD starts with an active noise control (ANC) system receiving a reference microphone acoustic signal and an error microphone acoustic signal from the PLD. The ANC system then receives at least one of a motion signal or a pressure sensor signal from the PLD. The motion signal is based on a detected motion of the PLD and the pressure sensor signal is based on a detected compression of a portion of the PLD. The ANC system then determines whether vibrations of the PLD are detected based on at least one of the motion signal or the pressure sensor signal. When vibrations are not detected, the ANC system generates a first anti-noise signal based on the reference microphone acoustic signal and the error microphone acoustic signal and when vibrations are detected, the ANC system generates a second anti-noise signal. The second anti-noise signal may be based on the detected vibration. The ANC system generating the second anti-noise signal includes reconfiguring the ANC system. 
     In another embodiment, a computer-readable storage medium has stored therein instructions that, when executed by a processor, causes an active noise control (ANC) system to perform a method of active noise cancellation in a PLD. The method starts with the ANC system receiving a reference microphone acoustic signal and an error microphone acoustic signal from the PLD. The ANC system then receives at least one of a motion signal or a pressure sensor signal from the PLD. The motion signal is based on a detected motion of the PLD and the pressure sensor signal is based on a detected compression of a portion of the PLD. The ANC system then determines whether vibrations of the PLD are detected based on at least one of the motion signal or the pressure sensor signal. When vibrations are not detected, the ANC system generates a first anti-noise signal based on the reference microphone acoustic signal and the error microphone acoustic signal. When vibrations are detected, the ANC system generates a second anti-noise signal, wherein the processor reconfigures the ANC system to generate the second anti-noise signal. 
     The above summary does not include an exhaustive list of all aspects of the present invention. It is contemplated that the invention includes all systems, apparatuses and methods that can be practiced from all suitable combinations of the various aspects summarized above, as well as those disclosed in the Detailed Description below and particularly pointed out in the claims filed with the application. Such combinations may have particular advantages not specifically recited in the above summary. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The embodiments of the invention are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings in which like references indicate similar elements. It should be noted that references to “an” or “one” embodiment of the invention in this disclosure are not necessarily to the same embodiment, and they mean at least one. In the drawings: 
         FIG. 1  illustrates examples of personal listening devices that may be coupled with a consumer electronic device according to one embodiment of the invention. 
         FIG. 2  illustrates an exemplary system for active noise cancellation in a personal listening device according to one embodiment of the invention. 
         FIG. 3  illustrates a block diagram of the details of an exemplary system for active noise cancellation in a personal listening device according to one embodiment of the invention. 
         FIG. 4  illustrates a flow diagram of an example method for active noise cancellation in a personal listening device according to one embodiment of the invention. 
         FIG. 5  is a block diagram of exemplary components of an electronic device used with a personal listening device in accordance with aspects of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known circuits, structures, and techniques have not been shown to avoid obscuring the understanding of this description. 
       FIG. 1  illustrates an example of personal listening devices (PLD)  200  that may be coupled with a consumer electronic device according to one embodiment of the invention. The personal listening devices may be, for instance, a headphone, an earphone, or a pair of earbuds. The personal listening device  200  may also be closed (or sealed) headphone, earphone, or pair of earbuds such that the speaker opening of the personal listening device  200  is “sealed” by the contact of the ear to the device  200  housing at the region surrounding the speaker&#39;s opening. The personal listening device  200  may also be a loosely fitting earbuds. 
     As shown in  FIG. 1 , the personal listening device  200  may be a headphone  200  (left) that include a pair of earcups that are placed over the user&#39;s ears or may be a pair of earbuds  200  (right) that are placed inside the user&#39;s ears. Embodiments of the invention may also use other types of personal listening devices  200 . The personal listening device  200  may be coupled to an electronic device  10  that transmits audio signal to the personal listening device  200 . The electronic device  10  may be a mobile or a stationary personal consumer electronic device. The personal listening device  200  may be coupled to the electronic device  10  via a wire  120  as shown in  FIG. 1  or via wireless connections (not shown). The personal listening devices  200  in  FIG. 1  are double-earpiece headsets. It is understood that single-earpiece or monaural headsets may also be used. As the user is using the personal listening device to listen to audio signals from the electronic device  10 , environmental noise may also be present (e.g., noise sources in  FIG. 1 ). 
       FIG. 2  illustrates an exemplary system for active noise cancellation in a personal listening device according to one embodiment of the invention. The system in  FIG. 2  illustrates an electronic device  10  used with an example of the right side of a personal listening device  200  according to one embodiment of the invention. It is understood that a similar configuration may be included in the left side of the personal listening device  200 .  FIG. 2  also includes an active noise control (ANC) system  300  that generates the anti-noise signal that is outputted by a speaker  240 . While illustrated as being separate in  FIG. 2 , the ANC system  300  may be included in the personal listening device  200 &#39;s housing  210  according to one embodiment. In another embodiment, the ANC system  300  may be included in the electronic device  10 . 
     Referring to  FIG. 2 , the personal listening device  200  comprises a housing  210  that has installed therein at least one reference microphone  220 , an error microphone  230 , a speaker  240 , an inertial sensor  250 , and a pressure sensor  260 . The housing  210  may be an earphone housing. The reference microphone  220  and the error microphone  230  may be air interface sound pickup devices that convert sound into an electrical signal. In one embodiment, the reference microphone  220  is located within the housing  210 . The reference microphone  220  may be located behind the speaker  240  as shown to pick up primary noise (e.g., external noise, ambient noise, environmental noise, voice, etc.) that is external to the personal listening device  200  and that may be heard by a user of the personal listening device  200 . In some embodiments, the reference microphone  220  is installed on the exterior of the housing  210  such that the reference microphone  220  is mounted externally to the personal listening device  200  to pick up the primary noise. In one embodiment, the reference microphone  220  is mounted on the bridge or headband portion of a headphone. As shown in  FIG. 2 , the reference microphone  220  may face the opposite direction of the eardrum. In the embodiment where a plurality of reference microphones  220  are included in the personal listening device  200 , the plurality of reference microphones  220  can form one or more microphone arrays that may be used to create microphone array beams (i.e., beamformers) which can be steered to a given direction by emphasizing and deemphasizing selected microphones  220 . In one embodiment, the beamformers may be steered towards the primary noise source. Similarly, the microphone arrays can also exhibit or provide nulls in other given directions. Accordingly, the beamforming process, also referred to as spatial filtering, may be a signal processing technique using the microphone array for directional sound reception. The reference microphone  220  generates and transmits a reference signal to the ANC system  300 . 
     As shown in  FIG. 2 , the speaker  240  receives the desired audio signal (e.g., desired audio content) from the electronic device  10  and generates the desired audio signal for the user of the personal listening device  200 . The speaker  240  also receives an anti-noise signal from the ANC system  300 . The speaker  240  outputs the anti-noise signal which is a signal that cancels the environmental noise from the audio signal heard by the user of the personal listening device  200 . 
     As shown in  FIG. 2 , the error microphone  230  is located in front of the speaker  240  at a position that is closest to the user&#39;s canal. The error microphone faces away from the direction of the user&#39;s eardrum. Accordingly, the error microphone  230  receives the acoustic signals that are outputted by the speaker  240  which are heard by the user of the personal listening device  200 . The acoustic signals that are outputted by the speaker  240  may include unwanted noise that was not cancelled by the ANC system  300 . The error microphone  230  thus monitors the performance of the ANC system  300  by detecting the unwanted noise and generating and transmitting an error signal to the ANC system  300 . The unwanted noise may be due to the frequency response of the overall sound producing system, which includes the electro-acoustic response of the personal listening device  200  and the physical or acoustic features of the user&#39;s ear up to the eardrum that can vary substantially during normal end-user operation, as well as across different users. Using the error signal from the error microphone  230 , the ANC system  300  may implement an adaptive filtering scheme (e.g., filtered-x least minimum square algorithm (FXLMS)). 
     The inertial sensor  250  included in the personal listening device  200  may be a sensing device that measures proper acceleration in three directions, X, Y, and Z or in only one or two directions. For example, the inertial sensor  250  may be an accelerometer, a gyroscope, or microelectromechanical system (MEMS). In other embodiments, a force sensor or a position, orientation and movement sensor may be used in lieu of the inertial sensor  250 . In one embodiment, the inertial sensor  250  detects motion of the PLD and generates a motion signal that is transmitted to the ANC system  300 . For instance, when the user of the personal listening device  200  walks, runs, jumps or is on a rough or bumpy ride in a vehicle, the inertial sensor  250  may detect the vibrations of the personal listening device  200 . 
     The pressure sensor  260  included in the personal listening device  200  may be a sensing device that measures the compression of a portion of the personal listening device  200  and to generate pressure sensor signal. The pressure sensor  260  may be an optical pressure sensor, a capacitive pressure sensor, a piezoelectric pressure sensor, an electromagnetic pressure sensor, etc. In one embodiment, the earpad portion of the personal listening device  200  may be made of a soft material (e.g., soft leather, semi-leather, special urethane, etc.). When the user of the personal listening device  200  walks, runs, or is on a rough or bumpy ride in a vehicle, the earpad portion of the personal listening device  200  may compress and decompress against the user&#39;s ear in accordance with the vibrations of the personal listening device  200 . The pressure sensor  260  may detect the compression (and decompression) of the earpad portion, for instance, and generate a pressure sensor signal that is transmitted to the ANC system  300 . In one embodiment, the pressure sensor signal may be used to determine whether the personal listening device is vibrating. 
     As shown in  FIG. 2 , the ANC system  300  comprises a processor  320 , a memory device  330 , a vibration detector  310 , and an ANC adaptive anti-noise generator  340 . The memory device  330 , the vibration detector  310  and the ANC adaptive anti-noise generator  340  may be coupled to the processor  320 . The memory device  330  may include one or more different types of storage such as hard disk drive storage, nonvolatile memory, and volatile memory such as dynamic random access memory. The processor  320  may be a microprocessor, a microcontroller, a digital signal processor, or a central processing unit. The term “processor” may refer to a device having two or more processing units or elements, e.g. a CPU with multiple processing cores. The processor  320  may be used to control the operations of the ANC system  300  by executing software instructions or code stored in the memory device  330 . For instance, the processor  320  may execute software instructions or code stored in the memory device  330  that causes the processor  320  to perform a method for active noise cancellation in the personal listening device  200  according to an embodiment of the invention. The ANC system  300  operates while the user is for example listening to a digital music file that is stored in the electronic device  10 . 
     As shown in  FIG. 2 , the vibration detector  310  may detect a vibration of the personal listening device  200  based on at least one of the motion signal from the inertial sensor  250  or the pressure sensor signal from the pressure sensor  260 . The processor  320  may control the vibration detector  310  by executing software instructions or code stored in the memory device  330  to determine whether vibrations of the personal listening device  200  are detected based on the received motion signal from the inertial sensor  250  and the pressure sensor signal from the pressure sensor  260 . In one embodiment, the ANC anti-noise generator  340  generates a first anti-noise signal when vibrations are not detected by the vibration detector  310  and generates a second anti-noise signal when vibrations are detected by the vibration detector  310 . The second anti-noise signal may be based on the detected vibrations. In one embodiment, the processor  320  reconfigures the ANC system  300  for the ANC anti-noise generator  340  to generate the second anti-noise signal. 
     As shown in  FIG. 2 , the ANC adaptive anti-noise generator  340  receives the reference signal from the reference microphone  220  and the desired audio signal from the electronic device  10 . The reference signal may be digitized and processed by the ANC adaptive anti-noise generator  340  to generate the anti-noise signal that is transmitted to the speaker  240  inside the personal listening device  200 .  FIG. 3  illustrates a block diagram of the details of the ANC adaptive anti-noise generator  340  according to one embodiment of the invention. The ANC adaptive anti-noise generator  340  may include at least one adaptive filter  350  and an adaptive controller  360 . As shown in  FIG. 3 , the at least one adaptive filter  350  receives the reference signal and generates the anti-noise signal that is electronically designed so as to have the proper pressure amplitude and phase that destructively interferes with the unwanted ambient noise captured by the reference microphone  220 . The speaker  240  then outputs the anti-noise signal. 
     The ANC adaptive anti-noise generator  340  also receives the error signal from the error microphone  230  as discussed above that monitors the performance of the ANC system  300 . The error signal may be digitized and processed by the ANC adaptive anti-noise generator  340 . In the implementation of the adaptive ANC system  300  based on the FXLMS algorithm, an identification of a secondary path is required. Thus, there are two adaptive filters operating simultaneously for each channel, the control filter and the secondary path filter. The identification and/or modeling of the transfer function for the secondary path can be performed online using the downlink (playback) signal as the training signal for the LMS algorithm. 
     The implementation of an adaptive ANC system  300  based on the FXLMS algorithm also uses the vibration detector  310  to detect when the personal listening device  200  is vibrating. When the personal listening device  200  is vibrating due to the user walking, running, jumping, etc., the reference signal from the reference microphone  220  and the error signal from the error microphone  230  may be inaccurate in that the signals may include the vibration and/or compression of the personal listening device  200  as part of the noise to be cancelled by the ANC system  300 . Thus, the signals from the reference microphone  220  and from the error microphone  230  when the personal listening device  200  may act as a disturbance signal to the adaptive filter algorithms, possibly causing the divergence of the filters. Accordingly, the vibration detector  310  is used to determine when the personal listening device  200  is vibrating. When vibrations of the personal listening device  200  are detected, the processor  320  may prevent the corrupted reference signal and the corrupted error signal to be used to adapt the filter(s)  350  in the ANC adaptive anti-noise generator  340  of the ANC system  300 . Thus, the at least one adaptive filter  350  is prevented from diverging or becoming unstable. In one embodiment, the ANC adaptive anti-noise generator  34  generates an anti-noise signal based on the reference signal and the error signal when vibrations are not detected. However, when the personal listening device  200  is vibrating, the anti-noise signal that is based on the reference signal and the error signal causes the personal listening device  200  to generate an anti-noise that includes artifacts. Accordingly, when the vibration detector  310  detects vibrations, the ANC adaptive anti-noise generator  340  generates a second anti-noise signal based on detected vibrations. 
     In one embodiment, the vibration detector  310  receives at least one of the motion signal from the inertial sensor  250  or the pressure sensor signal from the pressure sensor  260 . The motion signal and the pressure sensor signal may be digitized and processed by the vibration detector  310  to determine if the personal listening device  200  is vibrating. In one embodiment, the memory device  330  stores a plurality of predetermined sensor data patterns including patterns that indicate the contexts of: walking, jumping, running, and vehicle motions or vibrations. In this embodiment, the vibration detector  310  establishes that vibrations of the personal listening device  200  are detected when the vibration detector  310  matches at least one of the motion signal or the pressure sensor signal with at least one of the predetermined sensor data patterns. 
     In one embodiment, when the vibration detector  310  detects vibrations, the processor  320  reconfigures the ANC system  300  for the ANC anti-noise generator  340  to generate the second anti-noise based on the detected vibrations. The processor  320  in the ANC system  300  may implement a feed forward, a feedback, or a hybrid noise control algorithm. The processor  320  may reconfigure the ANC system  300  by for example adapting the coefficients of an finite impulse response (FIR) filter (e.g., secondary path) using a LMS adaptive algorithm, adapting the coefficients of an FIR filter (e.g., the control filter path) according to a filtered-x LMS algorithm, and reconfigure the ANC system  300  to alter the adaptation of the FIR filters when vibration of the personal listening device  200  is detected. For instance, when vibrations are detected, the processor  320  may lock the filter coefficients of an adaptive filter  350  included in the ANC system  300  or the processor may alternatively lock filtering by the adaptive filter  350 . The locking of the filter coefficients or the locking of the filtering may also be referred to as “freezing” the adaptive filter. Accordingly, the adaptive filter  350  remains in a previously acceptable state (e.g., not diverging or unstable) and generates anti-noise signals. In another embodiment, to reconfigure the ANC system  300 , the processor  320  changes a speed of updates made to the adaptive filter  350  by the adaptive filter controller  360  included in the ANC system  300 . For instance, if the vibration detector  310  matches the motion signal or the pressure signal with the predetermined sensor data pattern associated with the context of walking, the processor  320  may increase the speed of the adaptive filter updates in between the steps and may slowdown the speed of the adaptive filter updates when the user&#39;s step occurs (e.g., when the user&#39;s foot hits the ground). Accordingly, the ANC system  300  accounts for the pressure level change in the earcup due to the user&#39;s steps affecting the reference microphone signal from the reference microphone  220 . In another embodiment, to reconfigure the ANC system  300  when vibrations are detected, the processor  320  selects predetermined adaptive filter coefficients associated with the at least one of the predetermined sensor data patterns. For instance, if the vibration detector  310  matches the motion signal or the pressure signal with the predetermined sensor data pattern associated with the context of walking, the processor  320  may select the predetermined adaptive filter coefficient associated with the context of walking. The predetermined adaptive filter coefficients associated with each of the contexts may be stored in the memory device  330 . In this embodiment, the processor  320  overrides the filter coefficients of the adaptive filter  350 , that were computed by the adaptive filter controller  360  included in the ANC system  300 , with the predetermined filter coefficients that were selected. In another embodiment, to reconfigure the ANC system  300  when vibrations are detected, the processor  320  applies a jacket on filter coefficients of an adaptive filter  350  included in the ANC system  300 . The jacket establishes a maximum and a minimum for desired filter coefficients. Accordingly, when the vibrations of the personal listening device  200  cause the adaptive filter controller  360  to generate erroneous coefficients for the adaptive filter  350  in the ANC system  300 , the processor  320  applies the jacket to the erroneous coefficients which causes the erroneous coefficients that exceed the maximum established by the jacket or that fall below the minimum established by the jacket to be corrected by the processor  320 . The corrected values of the coefficients are values that are within the jacket&#39;s established limits. In one embodiment, when vibrations are detected, the processor  320  may mute the anti-noise signal output from the speaker  240 . However, it is noted that muting the anti-noise signal when the vibrations are detected in the personal listening device  200  may introduce artifacts in the acoustic signal being heard by the user. 
     Moreover, the following embodiments of the invention may be described as a process, which is usually depicted as a flowchart, a flow diagram, a structure diagram, or a block diagram. Although a flowchart may describe the operations as a sequential process, many of the operations can be performed in parallel or concurrently. In addition, the order of the operations may be re-arranged. A process is terminated when its operations are completed. A process may correspond to a method, a procedure, etc. 
       FIG. 4  illustrates a flow diagram of an example method of improving active noise cancellation in a personal listening device according to one embodiment of the invention. The method  400  in  FIG. 4  starts with the ANC system  300  receiving a reference microphone acoustic signal and an error microphone acoustic signal from the personal listening device  200  at Block  401 . At Block  402 , the ANC system  300  receives at least one of a motion signal or a pressure sensor signal from the personal listening device  200 . The motion signal is based on a detected motion of the personal listening device and the pressure sensor signal is based on a detected compression of a portion of the personal listening device  200 . At Block  403 , the ANC system  300  determines whether vibrations of the personal listening device are detected based on at least one of the motion signal or the pressure sensor signal. If at Block  403 , the ANC system  300  determines that vibrations are not detected, the method  400  continues to Block  404  and the ANC system generates a first anti-noise signal that is based on the reference microphone acoustic signal and the error microphone acoustic signal. If at Block  403 , the ANC system  300  determines that vibrations are detected, the method  400  continues to Block  405  and the ANC system  300  generates a second anti-noise signal. The second anti-noise signal may be based on the detected vibration. In one embodiment, the ANC system  300  is reconfigured by the processor  320  to generate the second anti-noise signal at Block  405 . 
     A general description of suitable electronic devices for performing these functions is provided below with respect to  FIG. 5 . Specifically,  FIG. 5  is a block diagram depicting various components that may be present in electronic devices suitable for use with the present techniques. An example of a suitable electronic device includes a computer, a handheld portable electronic device, a tablet-style electronic device, etc. These types of electronic devices, as well as other electronic devices providing comparable voice communications capabilities (e.g., VoIP, telephone communications, etc.), may be used in conjunction with the present techniques. 
     Keeping the above points in mind,  FIG. 5  is a block diagram illustrating components that may be present in one such electronic device  10 , and which may allow the device  10  to function in accordance with the techniques discussed herein. The various functional blocks shown in  FIG. 5  may include hardware elements (including circuitry), software elements (including computer code stored on a computer-readable medium, such as a hard drive or system memory), or a combination of both hardware and software elements. It should be noted that  FIG. 5  is merely one example of a particular implementation and is merely intended to illustrate the types of components that may be present in the electronic device  10 . For example, in the illustrated embodiment, these components may include a display  12 , input/output (I/O) ports  14 , input structures  16 , one or more processors  18 , memory device(s)  20 , non-volatile storage  22 , expansion card(s)  24 , RF circuitry  26 , and power source  28 . 
     While the invention has been described in terms of several embodiments, those of ordinary skill in the art will recognize that the invention is not limited to the embodiments described, but can be practiced with modification and alteration within the spirit and scope of the appended claims. The description is thus to be regarded as illustrative instead of limiting. There are numerous other variations to different aspects of the invention described above, which in the interest of conciseness have not been provided in detail. Accordingly, other embodiments are within the scope of the claims.

Metadata:
Filing Date: 20150312
Publication Date: 20170711
Grant Date: 20170711
Priority Date: 20150312
Inventors: TERLIZZI JEFFREY
Assignee: APPLE INC
CPC Classifications: [{"code": "G10K2210/129", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/1083", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R2460/01", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/1091", "inventive": true, "first": true, "tree": "[]"}, {"code": "G10K11/178", "inventive": true, "first": false, "tree": "[]"}, {"code": "G10K2210/3226", "inventive": false, "first": false, "tree": "[]"}, {"code": "G10K2210/1081", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R2460/01", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/1091", "inventive": true, "first": false, "tree": "[]"}, {"code": "G10K2210/3229", "inventive": false, "first": false, "tree": "[]"}, {"code": "G10K11/17885", "inventive": true, "first": false, "tree": "[]"}, {"code": "G10K11/17883", "inventive": true, "first": false, "tree": "[]"}, {"code": "G10K11/17857", "inventive": true, "first": false, "tree": "[]"}, {"code": "G10K11/17854", "inventive": true, "first": false, "tree": "[]"}, {"code": "G10K11/17833", "inventive": true, "first": false, "tree": "[]"}, {"code": "G10K11/1783", "inventive": true, "first": false, "tree": "[]"}, {"code": "G10K11/17823", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/1083", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/1091", "inventive": true, "first": false, "tree": "[]"}, {"code": "G10K11/17885", "inventive": true, "first": false, "tree": "[]"}, {"code": "G10K11/17883", "inventive": true, "first": false, "tree": "[]"}, {"code": "G10K11/17857", "inventive": true, "first": false, "tree": "[]"}, {"code": "G10K11/17854", "inventive": true, "first": false, "tree": "[]"}, {"code": "G10K11/17833", "inventive": true, "first": false, "tree": "[]"}, {"code": "G10K11/17823", "inventive": true, "first": true, "tree": "[]"}, {"code": "G10K11/1783", "inventive": true, "first": false, "tree": "[]"}, {"code": "G10K11/17885", "inventive": true, "first": false, "tree": "[]"}, {"code": "G10K11/17883", "inventive": true, "first": false, "tree": "[]"}, {"code": "G10K11/17857", "inventive": true, "first": false, "tree": "[]"}, {"code": "G10K11/17854", "inventive": true, "first": false, "tree": "[]"}, {"code": "G10K11/17833", "inventive": true, "first": false, "tree": "[]"}, {"code": "G10K11/17823", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R1/1083", "inventive": true, "first": false, "tree": "[]"}, {"code": "G10K2210/3226", "inventive": false, "first": false, "tree": "[]"}, {"code": "G10K2210/3226", "inventive": false, "first": false, "tree": "[]"}, {"code": "G10K2210/129", "inventive": false, "first": false, "tree": "[]"}, {"code": "G10K2210/129", "inventive": false, "first": false, "tree": "[]"}, {"code": "G10K2210/1081", "inventive": false, "first": false, "tree": "[]"}, {"code": "G10K2210/1081", "inventive": false, "first": false, "tree": "[]"}, {"code": "G10K11/178", "inventive": true, "first": true, "tree": "[]"}, {"code": "G10K11/1783", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/1083", "inventive": true, "first": false, "tree": "[]"}, {"code": "G10K2210/3226", "inventive": false, "first": false, "tree": "[]"}, {"code": "G10K2210/129", "inventive": false, "first": false, "tree": "[]"}, {"code": "G10K2210/1081", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R2460/01", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R2460/01", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 55588539