Active Noise Cancellation (ANC) systems and methods that reduce latency to improve performance. In certain embodiments the systems sample a noise signal using a sample period to create a stream of digital signal data that is representative of the noise signal. A data transport layer carries the digital signal data to a signal processor. The transport layer temporally organizes the digital signal data to place the digital signal data within an initial phase of a sample period. The remaining phase of the sample period is set to a duration that allows the signal processor to process the digital signal data carried in the initial phase and to output the processed data during the same sample period. In this way, the processing of data occurs within one sample period and the latency is reduced and predictable.

A headphone having a speaker, a feedforward microphone, a feedback microphone, and an OED processor. The speaker is configured to transmit an audio playback signal based on a headphone audio signal. The feedforward microphone is configured to sense an ambient noise signal and transmit a feedforward microphone signal based at least in part on the ambient noise signal. The feedback microphone is configured to sense a total audio signal and transmit a feedback microphone signal based at least in part on the total audio signal, in which the total audio signal is the sum of the audio playback signal and at least a portion of the ambient noise level. The OED processor is configured to determine whether the headphone is off ear or on ear, based at least in part on the headphone audio signal, the feedforward microphone signal, and the feedback microphone signal.

A control system and method of selectively enabling an auto-shutoff feature of a control system for an aviation headset includes a power switch. The power switch is toggled and if the control system is in a powered down state, a startup sequence for the control system is initiated. During the startup sequence, a bias voltage detector checks for a bias voltage on a signal line of the headset. If a bias voltage is detected during the startup sequence, the auto-shutoff feature is enabled. The auto-shutoff feature periodically checks for a bias voltage and powers down the control system if no bias voltage is detected for a predetermined time interval. If no bias voltage is detected during startup, the auto-shutoff feature is disabled.

Systems and methods for low latency adaptive noise cancellation include an audio sensor to sense environmental noise and generate a noise signal, an audio processing path to receive an audio signal, process the audio signal through an interpolation filter, and generate a primary audio signal having a first sample frequency, an adaptive noise cancellation processor to receive the noise signal and generate an anti-noise signal, a direct interpolator to receive the anti-noise signal and generate an anti-noise signal having the first sample frequency, and a limiter to provide clipping to reduce a number of bits in the anti-noise signal, an adder operable to combine the primary audio signal and the anti-noise signal and generate a combined output signal, and a low latency filter to process the combined output signal.

With respect to a noise reduction device using a speaker and a microphone corresponding to each seat in a vehicle to reduce a noise in each seat, the noise reduction device includes, a signal processing unit configured to generate a canceling sound that reduces a noise at an ear of an occupant in a predetermined seat by using an auxiliary filter, an operation setting unit configured to disable operations of a speaker and a microphone corresponding to each empty seat in the vehicle, and an auxiliary filter setting unit configured to change a setting value of the auxiliary filter used by the signal processing unit to generate the canceling sound in accordance with the number of occupants in seats other than the predetermined seat, the seats affecting the noise in the predetermined seat.

A method performed by a wearable audio output device worn by a user is provided for controlling the reproduction of external noise and/or noise masking. A first a first lower-power detector determines if the user is in transport or a change in the user's transport. In response to the determination, a second higher-power detector exits a power saving state and determines a mode of the transport based. The wearable audio output device adjust a level of attenuation applied by the wearable audio output device to the external noise or adjusting a level of noise masking output by the wearable audio output device based on the determined mode of the transport.

An audio noise calibration circuit is provided comprising: a speaker, the speaker including a driver input; a switch having a first terminal, a second terminal, and an output, and wherein the switch is adapted to be responsive to a switching signal having at least a first switching state and a second switching state such that the first terminal of the switch is connected to the output of the switch when the switching signal is in the first switching state such that there is electrical connectivity between the first terminal and the output, and the second terminal of the switch is connected to the output of the switch when the switching signal is in the second switching state such that there is electrical connectivity between the second terminal and the output, and further wherein the output of the switch is connected to the driver input of the speaker; and an audio processing unit adapted to generate the switching signal such that when in the first switching state, an audio signal generated by the audio processing unit is transferred to the first terminal and then to the driver input of the speaker to be broadcast, generate the switching signal such that when in the second switching state, the driver input of the speaker is connected to a first portion of the audio processing unit such that the speaker operates as a microphone to acquire ambient noise sound, and an electrical output of the microphone that represents the ambient noise sound is processed by the first portion of the audio processing unit to generate a digitized ambient noise sound, and modify a next output audio signal based on the digitized ambient noise sound.

A noise-cancellation system, including: a plurality of sensors, each sensor outputting a sensor signal; a controller configured to receive each sensor signal, and, for each sensor signal, to: determine a power of the sensor signal at a plurality of frequencies; determine a measure of association between the power of the sensor signal at the plurality of frequencies and frequency; and determine whether the measure of association exceeds a predetermined threshold, wherein the processor is further configured to compute a noise-cancellation signal using the sensor signals, wherein the noise-cancellation signal is computed excluding sensor signals that were determined to exceed the predetermined threshold; and at least one actuator receiving the noise-cancellation signal and producing a noise-cancellation audio signal.

A quantizer and a method for a sigma-delta modulator circuit that may be used as a component within an adaptive-noise cancelling headphone are presented. An apparatus includes a quantizer to receive an input signal with successive input values and quantizes the input signal at discrete intervals. This is done by mapping the input value of the input signal at each interval to one of a plurality of quantization levels with three or more quantization levels that are non-uniformly spaced. The plurality of quantization levels has a first portion with two or more quantization levels having the same sign and being proportional to a first fraction having one as its numerator and two to a power of a first variable as its denominator, the first variable being an integer and having a different value for each of the two or more quantization levels of the first portion.

Systems and methods for low power lattice wave filters include an input operable to receive a digital input signal having a first sample rate, a first processing branch including a first delay element operable to receive the digital input signal and output a delayed digital input signal, a second processing branch including a first adder operable to receive the digital input signal and subtract a delayed feedback signal to produce a difference signal, a second adder operable to combine the delayed digital input signal and the difference signal to produce an output signal, and wherein the second processing branch further includes a feedback path including a second delay element operable to receive the output signal and output the delayed feedback signal. In a multistage topology, a register is disposed between each stage and clocked to reduce ripple power.