Cirrus Logic Inc.

Henry Chen

Brenton Robert Steele

Tom Harvey

Thomas Ivan Harvey

Vitaliy Sapozhnykov

Wind noise reduction in microphone signals. A first microphone signal is obtained from a first omnidirectional microphone and, contemporaneously, a second microphone signal is obtained from a second omnidirectional microphone. The first and second microphone signals are mixed to produce an output signal. Mixing involves weighting the first and second microphone signals by respective first and second signal weights to produce respective first and second weighted microphone signals, and summing the first and second weighted microphone signals together to produce the output signal. The first and second signal weights are calculated to minimize the power of the output signal.

Microphone mixing for wind noise reduction

An apparatus of reducing feedback noise in an acoustic system, the apparatus comprising: a first input for receiving a first signal derived from a first microphone associated with a first channel, the first signal comprising a first set of frequency sub-bands; a second input for receiving a second signal derived from a second microphone associated with a second channel, the second signal comprising second set of frequency sub-bands, the first and second sets of frequency sub-bands having matching frequency ranges, each frequency sub-band of the first and second sets of frequency sub-bands having a frequency of greater than a threshold frequency; and one or more processors configured to: determining feedback at a first speaker associated with the first channel; and responsive to determining feedback, mix each of the first set of frequency sub-bands with a corresponding one of the second set of frequency sub-bands to generate a mixed output signal comprising a mixed set of frequency sub-bands; wherein the mixing is performed so as to minimize the output power in each of the mixed set of frequency sub-bands whilst maintaining a stereo effect level difference in the mixed signal between the first and second signals within a level difference threshold range.

Methods, systems and apparatus for improved feedback control

Wind noise reduction is provided by obtaining a first signal from a first microphone and a contemporaneous second signal from a second microphone. A level of the first signal is compared to a level of the second signal, within a short or substantially instantaneous time frame. If the level of the first signal exceeds the level of the second signal by greater than a predefined difference threshold, a suppression is applied to the first signal.

Reducing instantaneous wind noise

A method of mixing microphone signals. First and second microphone signals are obtained from respective first and second microphones. In at least one affected subband, the first and second microphone signals are mixed to produce first and second mixed signals. At least one reference subband of the first and second microphone signals is processed in order to identify a binaural cue between the first and second microphone signals, the reference subband being distinct from the or each affected subband. The affected subband in the first and second mixed signals is modified in order to re-emphasize the identified binaural cue.

Retaining binaural cues when mixing microphone signals

A method of processing stereophonic audio content received in a first audio channel to be output to a first speaker and a second audio channel to be output to a second speaker, the method comprising: receiving the first and second audio channels; identifying a plurality of frequency sub-bands in the first audio channel; for each of the plurality of frequency sub-bands, determining an importance weighting based on a degree of audibility of the sub-band when combined with the remainder of sub-bands of the first audio channel and the second audio channel; on determining that a peak amplitude of the first audio channel is above a first clipping threshold, iteratively suppressing the sub-band of least importance in the first audio signal until the peak amplitude of the first audio signal is below the first clipping threshold; and outputting the suppressed first audio channel.

Methods and apparatus for processing stereophonic audio content

A method of processing an audio signal comprising a plurality of audio samples, the method comprising: receiving an audio sample of the plurality of audio samples; on determining that a peak amplitude of the audio sample falls outside a threshold range: suppressing the audio sample to within the threshold range by applying a strictly increasing non-linear function to the audio sample; and outputting the suppressed audio sample; and on determining that the peak amplitude of the audio sample falls within the threshold range or is equal to an upper or lower limit of the threshold range: outputting the received audio sample.

Methods and apparatus for soft clipping

A crosstalk canceller for reducing acoustic crosstalk at a time of audio playback is derived by forming a channel frequency response for a nominated playback geometry, and decomposing the channel frequency response to derive a decomposition element such as a singular value decomposition matrix. A value of the decomposition element, such as the smallest singular value, is then adjusted to reduce spectral coloration, and filter coefficients of a crosstalk cancellation filter are derived from the adjusted decomposition element.

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Cremorne, Australia

Henry Chen