A hybrid ANC system that can allow a feedback microphone to receive the same external noise as a feedforward microphone. A processor can generate an anti-noise signal based on what both microphones received to cancel a broader range of frequencies of the external noise.

A reference microphone for detecting noise is located under a first duct. The noise is in the form of a first plane wave in the first duct. A speaker is located on a top of the first duct. Connected to an upper part of the first duct is a second duct including an error microphone. The first plane wave in the first duct passes through an acoustic path and reaches the second duct. The error microphone detects the sound, and the speaker outputs a second plane wave with an opposite phase for canceling the first plane wave.

An apparatus for canceling noise at an ear speaker includes a wideband active noise cancellation filter having a first bandwidth and configured to generate a wideband anti-noise signal from a received reference noise signal, a narrowband active noise cancellation filter having a second bandwidth smaller than the first bandwidth and configured to generate a narrowband anti-noise signal from an error noise signal, a filter between the ear speaker and an error microphone and configured to generate a feedback noise signal, and a controller. The controller is configured to eliminate the error noise signal by modifying coefficients of the wideband active noise cancellation filter and the narrowband active noise cancellation filter in response to the wideband anti-noise signal, the narrowband anti-noise signal, and the feedback noise signal.

A device for reducing a rolling noise of a vehicle having at least one tire, the tire rolling on a roadway on a tire contact patch, wherein the device comprises at least one sound absorption element attached to the vehicle in front of, behind and/or laterally of the tire contact patch in the direction of travel (F) of the vehicle and having at least one resonance frequency and a curved first absorber membrane facing the tire contact patch, wherein the entire first absorber membrane is oriented normally to a direction of sound propagation (S) emanating from the tire contact patch, and the sound absorption element is located at a distance from the tire contact patch which corresponds to a multiple of half a wavelength (λ) assigned to the resonance frequency.

A sound system includes: a control system that generates a control signal for erasing noise from a signal of the noise in a place close to a head of a user who uses a seat; a silencing speaker system that is installed at the place close to the head of the user who uses the seat and includes M speaker units each emitting a sound based on the control signal; and an emission suppression unit including at least a sound absorbing material that easily absorbs only a sound having a frequency greater than or equal to a predetermined value and configured to make it difficult for the sound having the frequency greater than or equal to the predetermined value emitted from the silencing speaker units to be emitted to a place other than an ear of the user. The m-th silencing speaker unit is arranged so that a sound emitted from the m-th silencing speaker unit in the m-th silencing user direction is silenced at a place other than a place close to the head of the user who uses the seat due to coming around of a sound emitted from the m-th silencing speaker unit in a direction opposite to the m-th silencing user direction.

A noise control system comprises a feedforward module, a feedback module, an error pre-processing module, and a signal integrating module. The feedforward module is configured to receive a reference signal and output a feedforward anti-noise signal by performing feedforward processing to the reference signal. The feedback module is configured to receive an error signal and output a feedback anti-noise signal by performing feedback processing to the error signal. The error pre-processing module is configured to receive the error signal and output a first pre-processing signal to the feedforward module and a second pre-processing signal to the feedback module. The signal integrating module is configured to output an integrated anti-noise signal integrated from the feedforward anti-noise signal and the feedback anti-noise signal. Wherein the first pre-processing signal corresponds to the first part of the error signal which belongs to the first frequency region; the second pre-processing signal corresponds to the second part of the error signal which belongs to the second frequency region.

A hybrid ANC system that can allow a feedback microphone to receive the same external noise as a feedforward microphone. A processor can generate an anti-noise signal based on what both microphones received to cancel a broader range of frequencies of the external noise.

A method and apparatus for acoustic noise cancellation (“ANC”) in an audio headset. A combination of an analog feedforward path and at least one digital feedforward path enables the ANC facility to operate with the shorter delay inherent in analog electronics, but with the capability of better cancellation of reflections that digital feedforward allows.

A method of automated feedforward filter design comprising designing a feedforward filter for a system implementing active noise cancelling is described. The method includes designing the feedforward filter by determining a filter transfer function of the feedforward filter. Optionally, the filter transfer function is determined using a least square method. The method also includes determining the filter transfer function by defining a target transfer function of the feedforward filter and applying the least square method using the target transfer function to determine a filter expression for the filter transfer function. Optionally, the least square method is a weighted least square method.

The present invention provides an improved noise separation hybrid type ANC system, which includes a reference audio receiving device, an error audio receiving device, an audio output device, and an audio processing device. The audio processing device includes a feed-forward noise cancellation filter module, a feedback noise cancellation filter module, a mixer, a noise shaper, a first infinite impulse response filter, and a second infinite impulse response filter. When the noise bandwidth detector detects irregular noise, it adjusts the coefficient of the first infinite impulse response filter to set it as a low-pass filter; when regular noise is detected, the coefficient of the second infinite impulse response filter is adjusted to set it as a band-pass filter.