An active noise reduction device includes: an adaptive filter that generates a cancelling signal by applying an adaptive filter to a reference signal that has a correlation with noise in a space in an automobile, the cancelling signal being used to output a cancelling sound for reducing the noise; and a filter coefficient updater that calculates a coefficient of the adaptive filter based on a predetermined update equation. At a first timing at which the output of the cancelling sound is started, the filter coefficient updater uses a first coefficient as an initial value of the update equation, the first coefficient being the coefficient of the adaptive filter calculated by the filter coefficient updater at a second timing that is prior to the first timing.

An active noise control device includes a determination unit configured to determine whether an abnormality has occurred in an acceleration sensor based on a direct-current component of a reference signal acquired by the acceleration sensor attached to a vehicle, and a control unit configured to, when the determination unit determines that an abnormality has occurred in any of a plurality of the acceleration sensors, stop generation of the control signal based on the reference signal acquired by the acceleration sensor that has been determined to have the abnormality, and stop updating a filter coefficient of an adaptive filter configured to perform the filtering process on the reference signal acquired by the acceleration sensor that has been determined to have no abnormality.

A vibration cancellation method is a vibration cancellation method for canceling vibration arriving at a seat from outside of the seat, the vibration being transmitted to a user seated in the seat. The method includes canceling, by a vibration cancellation unit (4), a vibration by outputting a cancellation signal from a position close to a position where user's head is placed when a user is seated, the cancellation signal being obtained based on a reference signal and an error signal. The reference signal is obtained by a vibration sensor (2) disposed in a position close to a vibration source outside the seat in the seat, and the error signal is obtained by an error vibration sensor (3) disposed in the position close to the position where user's head is placed when the user is seated in the seat.

An echo filtering method, an electronic device, a computer-readable storage medium, and an echo filtering apparatus are disclosed. The electronic device includes M microphones and N speakers. M and N are integers greater than 1. The method includes: obtaining N speaker signals corresponding to the N speakers (302); obtaining M microphone signals corresponding to the M microphones (304); and performing at least direct sound filtering on the N speaker signals and the M microphone signals to obtain a target signal (306). By using this method, better echo filtering effect can be obtained.

A method, a system and a program product for evaluating an intestinal function using bowel sounds are disclosed. The method comprises the following steps: A. continuously monitoring an abdominal cavity of an examinee within a specific time by using an audio collection apparatus, collecting a bowel sound signal of an intestinal tract inside the abdominal cavity, and converting the bowel sound signal into a digital signal; B. using higher-order statistics (HOS), by a processing unit, to remove noise from the digital signal; C. using a fractal dimension algorithm, by the processing unit, to capture a high-complexity feature from the digital signal, and defining the high-complexity feature as an intestinal motility signal, and D. evaluating the intestinal function of the examinee, by the processing unit, according to the intestinal motility signal.

An acoustic noise reduction (ANR) headphone described herein has current detection circuitry that detects current consumed by an acoustic driver amplifier as a result of pressure changes due to a tapping of the headphone. Tapping may be performed to change an audio feature or operating mode of the audio system for the headphone. The current detection circuitry senses a characteristic of the current consumed by the acoustic driver amplifier that can be used to determine an occurrence of a tap event. Examples of a characteristic include an amplitude, waveform or duration of the sensed current. Advantageously, the ANR headphones avoid the need for control buttons to initiate the desired changes to the audio feature or operating mode.

This application discloses a method for reducing an occlusion effect of an earphone, and a related apparatus. The method is applied to an earphone having at least one microphone and a speaker. The method includes: detecting occurrence of at least one of the following events: a user speaks and the user is in a motion state; and triggering at least one of the following operations in response to the at least one event: processing the user's sound signal based on the at least one microphone to suppress an occlusion effect of the earphone, and playing an audio by using the speaker, to mask a sound signal in the user's auditory canal. Embodiments of this application can reduce or even eliminate the earphone occlusion effect, to improve user experience.

Methods and systems are provided for an automatic noise control system. Automatic noise control includes evaluating an amplitude of an acceleration acting on an acceleration sensor and generating a reference signal representative of the amplitude of the acceleration, the acceleration being representative of unwanted noise sound generated by a noise source, filtering the reference signal with a noise control transfer function to generate an anti-noise signal, and converting with a loudspeaker the anti-noise signal into anti-noise sound.

Technology described in this document can be embodied in a method that includes receiving a first input signal representing audio captured by a first sensor disposed in a signal path of an active noise reduction (ANR) device, and receiving a second input signal representing audio captured by a second sensor disposed in the signal path of the ANR device. The method also includes processing, by at least one compensator, the first input signal and the second input signal to generate a drive signal for an acoustic transducer of the ANR device. A gain applied to the signal path is at least 3 dB less relative to an ANR signal path having a single sensor.

In one aspect a method that includes receiving an input signal captured by one or more first sensors associated with an active noise reduction (ANR) device, and processing the input signal using a first filter disposed in an ANR signal path to generate a first signal for an acoustic transducer of the ANR device. The input signal is processed in a pass-through signal path disposed in parallel with the ANR signal path to generate a second signal for the acoustic transducer, wherein the pass-through signal path allows a portion of the input signal to pass through to the acoustic transducer in accordance with a variable gain. One or more second sensors detect an existence of a condition likely to cause instability in the pass-through signal path, and in response, the variable gain is adjusted. A driver signal for the acoustic transducer is generated using an output based on the adjusted gain.