A method for feedback detection by an electronic device is described. The method includes receiving a first microphone signal by a first microphone. A feedback loop includes the first microphone and a speaker. The method also includes receiving a second microphone signal by a second microphone that is outside of the feedback loop. A first signal based on the first microphone signal and a second signal based on the second microphone signal exhibit a higher correlation in presence of feedback and exhibit a lower correlation in absence of feedback. The method further includes determining a correlation based on the first microphone signal and the second microphone signal. The method additionally includes determining whether feedback is occurring based on the correlation.

An integrated circuit may include an output for providing an output signal to a transducer including both a source audio signal for playback to a listener and an anti-noise signal for countering the effect of ambient audio sounds in an acoustic output of the transducer, an ambient microphone input for receiving an ambient microphone signal indicative of the ambient audio sounds; an error microphone input for receiving an error microphone signal indicative of the output of the transducer and the ambient audio sounds at the transducer; and a processing circuit that implements a feedback path having a feedback response that generates a feedback anti-noise signal from the error microphone signal, wherein a signal gain of the feedback path is a function of the ambient microphone signal, and wherein the anti-noise signal comprises at least the feedback anti-noise signal.

A method of calibrating an earphone may include: securing an ANC earphone to a calibration fixture, the calibration fixture including an ear model configured to support the ANC earphone, the ear model having an ear canal configured to anatomically resemble a human ear canal and a concha configured to anatomically resemble a human ear concha, the ear canal extending from the concha to an inner end of the ear canal; generating, with the ANC earphone, an audio signal based on a reference tone; determining a characteristic of the audio signal; comparing the characteristic of the audio signal to a previously determined reference characteristic; and adjusting a gain value of the ANC earphone based on the comparing. Additional methods and apparatus are also disclosed.

A vehicular active noise reduction system includes a first microphone and first speaker disposed in a front-seat space, a second microphone and second speaker disposed in a back-seat space, and an active noise reduction device that performs control to output cancellation sound, to reduce noise in a cabin, from the first speaker and second speaker. When generating a first composite audio, the active noise reduction device removes audio components belonging to a frequency band relating to a second cancellation sound from audio collected by the first microphone, and when generating a second composite audio, removes audio components belonging to a frequency band relating to a first cancellation sound from audio collected by the second microphone.

An active noise reduction system includes a canceling sound output device configured to output a canceling sound, a plurality of noise microphones configured to generate a plurality of noise signals based on a noise, and a controller configured to control the canceling sound output device based on the plurality of noise signals, wherein the controller is configured to acquire the plurality of noise signals output from the plurality of noise microphones, select a reference signal and an error signal from among the plurality of noise signals, the reference signal corresponding to the noise, the error signal corresponding to an error between the noise and the canceling sound, generate a correction reference signal by removing a component of the canceling sound from the reference signal, and generate a control signal based on the correction reference signal, the control signal being a signal for controlling the canceling sound output device.

Embodiments of a diagnostic tool for an active noise cancelling system are presented. The diagnostic tool may generate an output from the active noise cancelling system and capture input to the active noise cancelling system that results from the output of the active noise cancelling system. The diagnostic tool may generate visual output to aid in evaluation of active noise cancelling systems.

A method for cancelling ambient audio sounds in the proximity of a transducer may include receiving an error microphone signal indicative of the output of the transducer and ambient audio sounds at the transducer. The method may also include generating an anti-noise signal for countering the effects of ambient audio sounds at an acoustic output of the transducer, wherein generating the anti-noise signal comprises applying a feedback filter having a response that generates a feedback anti-noise signal based on the error microphone signal and applying a variable gain element in series with the feedback filter. The method may further include monitoring whether an ambient audio event is occurring that could cause the feedback filter to generate an undesirable component in the anti-noise signal and controlling the gain of the variable gain element to reduce the undesirable component.

A signal processing method and an acoustic system are provided. When M sound sensors in a sound sensor module are in operation, they collect an ambient sound and generate M sound pickup signals. The ambient sound comprises a first sound from a speaker and a second sound from a target sound source. A signal processing circuit can perform a filtering operation on the M sound pickup signals based on M sets of target filtering parameters to obtain M filtered signals, and perform a synthesis operation on the M filtered signals to obtain a composite signal, and then perform a target operation on the composite signal. Since the M sets of target filtering parameters are configured to minimize a signal component from the speaker in the composite signal under a target constraint.

The disclosure provides an audio processing device comprising a first filter and a second filter. The first filter is configured to generate a first filtered signal based on an error signal, the error signal representative of audible sound at a target space. The second filter is configured to generate a second filtered signal based on the error signal. An anti-noise signal is generated based on the first filtered signal and the second filtered signal, and the anti-noise signal is included in the error signal. The first filter is connected to the second filter in parallel.

Methods and systems are described for mitigating acoustic feedback via an open ear device. In various examples, systems or methods may receive, via a first microphone and a second microphone positioned on an open ear device, a first audio signal and a second audio signal, respectively. The first audio signal and second audio signal may be converted to a first digital audio signal and a second digital audio signal. The first digital audio signal and second digital audio signal may be independently processed by an AFC to reduce acoustic feedback. A beamformer may adjust the first digital audio signal and second digital audio signal based on a target direction to create a beamformer digital audio signal. The beamformer digital audio signal may be processed via feedforward processing to create a target audio. The target audio may be phase shifted and transmitted to a loudspeaker positioned on the open ear device.