Cirrus Logic Inc.

Cirrus Logic International Semiconductor Limited

Nitin Kwatra

Jeffrey Donald Alderson

Jon David Hendrix

Ali Abdollahzadeh Milani

John L Melanson

Gautham Devendra Kamath

Dayong Zhou

Yang Lu

Antonio John Miller

Ning Li

Gabriel Vogel

Ryan A Hellman

D Hendrix Jon

Devendra Kamath Gautham

An acoustic signal processing system and method includes classification technology to classify a relationship between at least two sound components of a received sound signal. The exemplary sound components are ambient noise and localized noise. The classification technology dynamically determines a classification value that represents the relationship between the sound components and processes the sound signal in accordance with the acoustic signal classification to modify the sound signal. In at least one embodiment, dynamic classification of the relationship between sound components in a sound signal and responsive signal processing improve performance of systems, such as an active noise cancellation (ANC) system, by, for example, attenuating at least one of the sound components and/or enhancing at least one of the sound components. In an ANC system context, the sound components generally include noise components such as ambient noise and noise localized to a microphone.

Sound components relationship classification and responsive signal processing in an acoustic signal processing system

Calibrating devices communicating on the shared bus can assist in reducing conflicts on the bus and the resulting loss of data. For example, the timing of transmission of data from one device to another device on the shared bus may be adjusted to compensate for delays on the shared bus. For example, the transmitting device may adjust transmission to an earlier time than the programmed time by an amount proportional to a known delay, such that the signal arrives at a receiving device at the programmed time. When the adjustment is not able to obtain a desired alignment or would cause conflicts on the shared data bus, the timing may be adjusted to delay the transmission, rather than advance the transmission, such that the adjusted transmission time results in the receipt of the signal at the receiving device in an unused time window after the programmed time.

Timing adjustment to unused unit-interval on shared data bus

An active noise cancellation (ANC) system including a selectable decimation rate decimator that receives an oversampled digital input and has an input that selects the decimation rate, a filter that receives an output of the decimator, and a selectable interpolation rate interpolator that receives an output of the filter and has an input that selects the interpolation rate. The selectable decimation rate decimator and the selectable interpolation rate interpolator operate to provide a selectable sample rate for the filter based on the selected decimation and interpolation rates. The filter may be an anti-noise filter, feedback filter, and/or a filter that models an acoustic transfer function of the ANC system. Rate selection may be static, or dynamically controlled based on battery or ambient noise level. A ratio of the decimation rate and the interpolation rate is fixed independent of the dynamically controlled decimation and interpolation rates.

Active noise cancellation (ANC) system with selectable sample rates

A personal audio device, such as a wireless telephone, includes noise canceling circuit that adaptively generates an anti-noise signal from a reference microphone signal and injects the anti-noise signal into the speaker or other transducer output to cause cancellation of ambient audio sounds. An error microphone may also be provided proximate the speaker to estimate an electro-acoustical path from the noise canceling circuit through the transducer. A processing circuit uses the reference and/or error microphone, optionally along with a microphone provided for capturing near-end speech, to determine whether one of the reference or error microphones is obstructed by comparing their received signal content and takes action to avoid generation of erroneous anti-noise.

Mic covering detection in personal audio devices

A personal audio device, such as a wireless telephone, includes noise canceling that adaptively generates an anti-noise signal from a reference microphone signal and injects the anti-noise signal into the speaker or other transducer output to cause cancellation of ambient audio sounds. An error microphone is provided proximate the speaker to measure the output of the transducer in order to control the adaptation of the anti-noise signal and to estimate an electro-acoustical path from the noise canceling circuit through the transducer. The anti-noise signal is adaptively generated to minimize the ambient audio sounds at the error microphone. A processing circuit that performs the adaptive noise canceling (ANC) function also filters one or both of the reference and/or error microphone signals, to bias the adaptation of the adaptive filter in one or more frequency regions to alter a degree of the minimization of the ambient audio sounds at the error microphone.

Bandlimiting anti-noise in personal audio devices having adaptive noise cancellation (ANC)

An integrated circuit may include an output for providing a signal to a transducer including both source audio for playback to a listener and an anti-noise signal for countering the effects of ambient audio sounds in an acoustic output of the transducer, a microphone input for receiving a microphone signal indicative of ambient sounds at the transducer, a link control input for receiving link control information of a communications link coupling the integrated circuit to the transducer and/or a microphone for generating the microphone signal, wherein the link control information includes a link quality metric of the communications link, and a processing circuit comprising a filter having a response that generates the anti-noise signal in conformity with the microphone signal to minimize the ambient sounds at the acoustic output of the transducer, wherein the processing circuit modifies generation of the anti-noise signal responsive to the link quality metric.

Systems and methods for distributed adaptive noise cancellation

In accordance with embodiments of the present disclosure, a processing circuit may implement an adaptive filter, a first signal injection portion which injects a first additional signal into a first frequency range content source audio signal, and a second signal injection portion which injects a second additional signal into a second frequency range content source audio signal, wherein the first additional signal and the second additional signal are substantially different. The adaptive filter may have a response that generates the antinoise signal from the reference microphone signal to reduce the presence of the ambient audio sounds at the acoustic output, wherein the response of the adaptive filter is shaped in conformity with the reference microphone signal and the error microphone signal by adapting the response of the adaptive filter to minimize the ambient audio sounds in the error microphone signal, wherein the antinoise signal is combined with at least the first frequency range content source audio signal.

Systems and methods for adaptive active noise cancellation for multiple-driver personal audio device

A personal audio device, such as a wireless telephone, includes an adaptive noise canceling (ANC) circuit that adaptively generates an anti-noise signal from a reference microphone signal that measures the ambient audio and an error microphone signal that measures the output of an output transducer plus any ambient audio at that location and injects the anti-noise signal at the transducer output to cause cancellation of ambient audio sounds. A processing circuit uses the reference and error microphone to generate the anti-noise signal, which can be generated by an adaptive filter operating at a multiple of the ANC coefficient update rate. Downlink audio can be combined with the high data rate anti-noise signal by interpolation. High-pass filters in the control paths reduce DC offset in the ANC circuits, and ANC coefficient adaptation can be halted when downlink audio is not detected.

Adaptive noise canceling architecture for a personal audio device

Systems and methods of the present disclosure include analyzing and comparing transfer functions associated with a plurality of electro-acoustic paths for transducers of a personal audio device to determine proximity of the transducers to respective ears of a listener of the personal audio device, quality of acoustic seals associated with the transducers, and for one or more other purposes.

Systems and methods for sharing secondary path information between audio channels in an adaptive noise cancellation system

A personal audio device, such as a wireless telephone, includes an adaptive noise canceling (ANC) circuit that adaptively generates an anti-noise signal from a reference microphone signal and injects the anti-noise signal into the speaker or other transducer output to cause cancellation of ambient audio sounds. An error microphone is also provided proximate the speaker to measure the ambient sounds and transducer output near the transducer, thus providing an indication of the effectiveness of the noise canceling. A processing circuit uses the reference and/or error microphone, optionally along with a microphone provided for capturing near-end speech, to determine whether the ANC circuit is incorrectly adapting or may incorrectly adapt to the instant acoustic environment and/or whether the anti-noise signal may be incorrect and/or disruptive and then take action in the processing circuit to prevent or remedy such conditions.

Oversight control of an adaptive noise canceler in a personal audio device

In accordance with systems and methods of the present disclosure, an adaptive noise cancellation system may include an alignment filter configured to correct misalignment of a reference microphone signal and an error microphone signal by generating a misalignment correction signal.

Hybrid adaptive noise cancellation system with filtered error microphone signal

Based on transducer status input signals indicative of whether headphones housing respective transducers are engaged with ears of a listener, a processing circuit may determine whether the headphones are engaged with respective ears of the listener. Responsive to determining that at least one of the headphones is not engaged with its respective ear, the processing circuit may modify at least one of a first output signal to the first transducer and a second output signal to the second transducer such that at least one of the first output signal and the second output signal is different than such signal would be if the headphones were engaged with their respective ears.

Systems and methods for enhancing performance of audio transducer based on detection of transducer status

A personal audio device, such as a wireless telephone, includes noise canceling circuit that adaptively generates an anti-noise signal from a reference microphone signal and injects the anti-noise signal into the speaker or other transducer output to cause cancellation of ambient audio sounds. An error microphone may also be provided proximate the speaker to measure the output of the transducer in order to control the adaptation of the anti-noise signal and to estimate an electro-acoustical path from the noise canceling circuit through the transducer. A processing circuit that performs the adaptive noise canceling (ANC) function also either adjusts the frequency response of the anti-noise signal with respect to the reference microphone signal, and/or by adjusting the response of the adaptive filter independent of the adaptation provided by the reference microphone signal.

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Austin, TX, United States of America

Nitin Kwatra