A noise-cancellation system, including: a noise-cancellation filter configured to generate a noise-cancellation signal; an actuator configured to receive the noise-cancellation signal and to transduce a noise-cancellation audio signal based on the noise-cancellation signal, the noise-cancellation audio signal destructively interfering with an undesired noise in a noise-cancellation zone in a predefined volume; an error sensor configured to output an error sensor signal, the error sensor signal being representative of residual undesired noise in the noise-cancellation zone; a performance cost filter configured to receive and filter the error sensor signal and to output a performance cost filter signal, the performance cost filter signal being representative of the error sensor signal as weighted by a performance cost function; and an adjustment module configured to receive the performance cost filter signal and to adjust the noise-cancellation filter such that the noise-cancellation audio signal minimizes the performance cost filter signal.

A system and method for disabling adaptation in an adaptive feedforward control system at low speeds. The method includes generating a noise signal representative of undesired noise detected by a noise sensor of a vehicle and generating a noise-cancellation signal via a controller within the vehicle. Residual noise resulting from the combination of the acoustic energy of the noise-cancellation signal and the undesired noise is detected by a reference sensor, which generates an error signal based on the residual noise. The error signal and a speed signal from a speed sensor on the vehicle are transmitted to an adaptive processing module for the generation of a filter update signal. The adaptive processing module selectively permits or prevents the filter update signal to adapt filter coefficients of a filter when the speed signal is within a set of conditions.

A noise-cancellation system includes a noise-cancellation filter configured to generate a noise-cancellation signal based on a noise signal received from a noise sensor; an actuator disposed at a first location within a predefined volume and configured to receive the noise-cancellation signal and to transduce a noise-cancellation audio signal within the predefined volume; a reference sensor disposed at a second location within the predefined volume and to output a reference sensor signal, the reference sensor signal being representative of an undesired noise at the second location; a filter configured to filter the noise-cancellation signal and the reference sensor signal to output a filter output signal, the filter output signal representing an estimate of the undesired nose at a third location remote from the first location and the second location; and an adjustment module configured to adjust the noise-cancellation filter, based on the filter output signal, such that the noise-cancellation audio signal destructively interferes with the undesired noise at the third location.

A system and method includes a loudspeaker having a first, low-frequency driver and a second, high-frequency driver. An error microphone is disposed near the loudspeaker and receives sound output by both drivers as well as noise. An estimation of the secondary path between the drivers and the microphones is determined, and playback audio is applied to the estimation. The output of the estimation is subtracted from the output of the microphone to determine anti-noise. This anti-noise is used to modify audio data sent to the first, low-frequency driver; the audio data is sent directly to the second, high-frequency driver.

Exposure to ultrasound energy emitted by remote object detection systems on vehicles is reduced for vehicle occupants. An automotive vehicle has a passenger cabin and a remote sensing system including ultrasonic transceivers mounted for sensing external objects. An ultrasonic microphone is disposed to sense an ultrasonic wave entering the passenger cabin at greater than 30 kHz. An antinoise processor calculates an antinoise signal adapted to at least partially cancel the ultrasonic wave at a predetermined location in the cabin. An amplifier is coupled to the processor for amplifying the antinoise signal by a predetermined gain. An ultrasonic speaker is coupled to the amplifier to project the antinoise signal into the predetermined location to attenuate the ultrasonic wave at the predetermined location.

According to one embodiment, a noise reduction apparatus includes a speaker, a generator and a controller. The speaker outputs control sound. The generator generates self-excited sound. The controller controls a phase and an amplitude of the control sound to reduce noise generated from a noise source, based on the control sound and the self-excited sound that is synchronized with the control sound.

Audio devices and methods are provided for detecting instability in an associated feedforward audio processing system. A microphone provides a feedforward signal for processing by a feedforward filter. The processed signal may provide noise reduction and/or sound enhancement associated with the surrounding environment. The processed signal contributes to a driver signal provided to an acoustic transducer, e.g., a driver, to produce acoustic signals for a user. A processor is configured to detect an indication of instability in one or more of the signals, and to adjust a phase response of the feedforward signal path in response to detecting the indication of instability.

A method to suppress noise emanating from an electrical power generator including the steps of: receiving sound emanating from the electrical power generator, wherein the sound is received in a duct for cooling air having passed through the generator; analyzing the received sound and, based on the analysis, generating a sound signal which represents a destructive sound to the received sound, and broadcasting a destructive sound into the duct, wherein the destructive sound corresponds to the sound signal.

A noise cancellation system comprising an audio identification unit configured to identify audio to which a noise cancellation process is to be applied, an output generation unit configured to generate one or more noise cancellation signals in dependence upon the identified audio, and two or more audio output units each configured to reproduce a respective subset of the generated one or more noise cancellation signals, such that the two or more audio output units are configured to produce different outputs.

A person support apparatus, such as a bed, cot, stretcher, or the like, includes an active noise cancellation device configured to generate a noise cancelling sound wave that is designed to cancel a noise sound wave. The active noise cancellation device may include speakers and a microphone. In other embodiments, the person support apparatus includes a sound emitting component and a transmitter adapted to send out a notification signal prior to activation of the sound emitting component. The notification signal provides information about a characteristic of the sound to be emitted by the sound emitting device. The recipient of the notification signal may then use the signal to cancel the sound that is to be emitted. In some embodiments, the person support apparatus acts as a conduit for notification signals of upcoming sounds, receiving and forwarding such notification signals from and to other devices.