Patent application number | Description | Published |
20100182062 | AUDIO PROCESSOR WITH INTERNAL OSCILLATOR-GENERATED AUDIO INTERMEDIATE FREQUENCY REFERENCE - An integrated circuit audio processor having an internal-oscillator generated intermediate frequency reference provides for operation of an audio processor without requiring an external master clock. Input audio streams are sample-rate converted to an intermediate sample rate derived from the internal oscillator, which may be an LC oscillator. One or more output audio streams are generated from the one or more input audio streams at the intermediate sample rate and are converted from the intermediate sample rate to corresponding output sample rates. A divider generates the intermediate sample rate from the oscillator output, and is programmed to control the intermediate sample rate to ensure that the intermediate sample rate is in the proper range for operation of the integrated circuit. The divider can be programmed to accommodate changes in process, voltage and/or temperature of the IC, so that the intermediate sample rate is maintained near an expected frequency. | 07-22-2010 |
20120207317 | EAR-COUPLING DETECTION AND ADJUSTMENT OF ADAPTIVE RESPONSE IN NOISE-CANCELING IN PERSONAL AUDIO DEVICES - 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 estimate an electro-acoustical path from the noise canceling circuit through the transducer. A processing circuit determines a degree of coupling between the user's ear and the transducer and adjusts the adaptive cancellation of the ambient sounds to prevent erroneous and possibly disruptive generation of the anti-noise signal if the degree of coupling lies either below or above a range of normal operating ear contact pressure. | 08-16-2012 |
20120308024 | BANDLIMITING ANTI-NOISE IN PERSONAL AUDIO DEVICES HAVING ADAPTIVE NOISE CANCELLATION (ANC) - 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. | 12-06-2012 |
20120308025 | ADAPTIVE NOISE CANCELING ARCHITECTURE FOR A 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. | 12-06-2012 |
20120308026 | FILTER ARCHITECTURE FOR AN ADAPTIVE NOISE CANCELER IN A PERSONAL AUDIO DEVICE - A personal audio device, such as a wireless telephone, includes an adaptive noise canceling (ANC) circuit that generates an anti-noise signal from a reference microphone signal and injects the anti-noise signal into the speaker or other transducer output to cancel ambient audio sounds. A processing circuit implements one or more adaptive filters that control the generation of the anti-noise signal. At least one of the adaptive filters is partitioned into a first portion having a fixed frequency response and a second portion having a variable frequency response. The partitioned filter may be an adaptive filter that generates the anti-noise signal directly from the reference microphone signal. An error microphone may be provided to measure the ambient sounds and transducer output near the transducer, and a secondary path adaptive filter included to generate an error signal from the error microphone signal, which may be partitioned, alone or in combination. | 12-06-2012 |
20130301847 | SEQUENCED ADAPTATION OF ANTI-NOISE GENERATOR RESPONSE AND SECONDARY PATH RESPONSE IN AN ADAPTIVE NOISE CANCELING 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 to the speaker to provide an error signal indicative of the effectiveness of the noise cancellation. A secondary path estimating adaptive filter is used to estimate the electro-acoustical path from the noise canceling circuit through the transducer so that source audio can be removed from the error signal. Adaptation of adaptive filters is sequenced so that update of their coefficients does not cause instability or error in the update. A level of the source audio with respect to the ambient audio can be determined to determine whether the system may generate erroneous anti-noise and/or become unstable. | 11-14-2013 |
20130301848 | DOWNLINK TONE DETECTION AND ADAPTATION OF A SECONDARY PATH RESPONSE MODEL IN AN ADAPTIVE NOISE CANCELING SYSTEM - An adaptive noise canceling (ANC) circuit adaptively generates an anti-noise signal from a reference microphone signal that is injected into the speaker or other transducer output to cause cancellation of ambient audio sounds. An error microphone proximate the speaker provides an error signal. A secondary path estimating adaptive filter estimates the electro-acoustical path from the noise canceling circuit through the transducer so that source audio can be removed from the error signal. Tones in the source audio, such as remote ringtones, present in downlink audio during initiation of a telephone call, are detected by a tone detector using accumulated tone persistence and non-silence hangover counting, and adaptation of the secondary path estimating adaptive filter is halted to prevent adapting to the tones. Adaptation of the adaptive filters is then sequenced so any disruption of the secondary path adaptive filter response is removed before allowing the anti-noise generating filter to adapt. | 11-14-2013 |
20140211953 | BANDLIMITING ANTI-NOISE IN PERSONAL AUDIO DEVICES HAVING ADAPTIVE NOISE CANCELLATION (ANC) - 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. | 07-31-2014 |