An active noise reduction device includes: a reference signal input terminal that receives a reference signal from a reference signal source attached to an automobile; a simulated vibration transfer characteristics filter unit that generates a second signal by correcting, using simulated vibration transfer characteristics, a first signal for outputting, from a loudspeaker attached to the automobile, a sound different from a canceling sound, the simulated vibration transfer characteristics simulating vibration transfer characteristics from the loudspeaker to the reference signal source; a first subtracter that outputs a corrected reference signal obtained by subtracting the second signal generated, from the reference signal received by the reference signal input terminal; and an adaptive filter unit that applies an adaptive filter to the corrected reference signal outputted from the first subtracter to generate a canceling signal to be used to output the canceling sound.

Various aspects include active noise reduction (ANR) devices and approaches, one approach including: receiving an input signal representing audio captured by a feedforward microphone of an ANR headphone; receiving an error signal representing audio captured by an error measurement sensor; generating an anti-noise signal configured to reduce a noise signal over a frequency range; and applying a gain to at least one of the input signal or the anti-noise signal over the frequency range based on the error signal, where the gain is calculated by: filtering the anti-noise signal over the frequency range to generate a filtered feedforward signal, and filtering the error signal over the frequency range to generate a filtered error signal; estimating a feedforward path contribution to the error signal; and determining the gain based on a correlation between the filtered error signal and the filtered feedforward signal with the assigned feedforward path contribution to the error signal.

For example, an apparatus for Active Acoustic Control (AAC) of an open acoustic headphone may include an input to receive input information including a residual-noise input including residual-noise information corresponding to a residual noise sensor of the open acoustic headphone, and a noise input including noise information corresponding to a noise sensor of the open acoustic headphone; a controller configured to determine a sound control pattern configured for AAC of the open acoustic headphone, the controller configured to identify a mounting-based parameter of the open acoustic headphone based on the input information, and to determine the sound control pattern based on the mounting-based parameter, the residual-noise input, and the noise input; and an output to output the sound control pattern to an acoustic transducer of the open acoustic headphone.

An audio system for an ear mountable playback device includes a speaker, an error microphone, which senses sound being output from the speaker, and a sound control processor. The processor is configured for controlling and/or monitoring a playback of a detection signal or a filtered version of the detection signal via the speaker, recording an error signal from the error microphone, and determining whether the playback device is in a first state, where the playback device is worn by a user, or in a second state, where the playback device is not worn by a user, based on processing of the error signal.

A noise reduction device includes a processor that converts a noise signal collected by a microphone disposed in a control space into a noise signal in a frequency domain, a storage that stores the converted noise signal in the frequency domain as a reference signal, and a signal generator that generates a noise reduction signal for reducing the noise signal collected by the microphone at a control position of the control space. The processor determines whether or not the noise signal is non-stationary noise based on a frequency characteristic of the converted noise signal in the frequency domain and a frequency characteristic of the reference signal. When it is determined that the noise signal is the non-stationary noise, the processor controls the signal generator so as to cancel generation of the noise reduction signal.

Provided is a speaker unit that constitutes a sound system that reduces noise in an open space, including: a housing; a driver; and a microphone, in which the microphone and the driver are provided in the housing such that sensitivity of the microphone to a signal output from the driver is lower.

A speaker (10) includes a radiation surface (15). The radiation surface (15) has a first region (15a), a second region (15b), and a third region (15c) between the first region (15a) and the second region (15b). When an axis passing through the third region (15c) and extending away from the radiation surface (15) is defined as a reference axis (10X), the speaker (10) forms a first wavefront (16a) propagating from the first region so as to approach the reference axis (10X) and a second wavefront (16b) propagating from the second region (15b) so as to approach the reference axis (10X).

A vehicle-implemented noise-cancellation system, includes: a noise-cancellation system disposed in a vehicle, the noise-cancellation system comprising an adaptive filter being adjusted according to a reference signal and an error signal, the adaptive filter outputting a noise-cancellation signal, which, when transduced into a noise-cancellation audio signal by a speaker, cancels road noise within at least one zone within a cabin of the vehicle; and an adjustment module configured to vary a power of the noise-cancellation signal or a rate of adaptation of the adaptive filter from a first value to a second value, passing through at least one intermediate value between the first value and the second value, based on a time-varying signal indicative of a signal-to-noise ratio of the reference signal with respect to a first criterion.

Active noise cancellation systems and methods include a feedforward path configured to receive a reference signal comprising ambient noise and adaptively generate an anti-noise signal to cancel the ambient noise and comprising an adaptive gain component configured to adaptively adjust a gain of the anti-noise signal, and a logic device configured to determine a leakage profile based on the adaptive gain component. The feedforward path includes a feedforward adaptive filter tuned to generate the anti-noise signal corresponding to the reference signal in accordance with the determined leakage profile. The leakage profile is selected from a plurality of stored leakage profiles that are tuned for a corresponding gain, and which corresponds to an ear coupling condition associated with a fit between the active noise cancellation system and a user. An adaptive transparency filter receives the reference signal and generates an ambient inclusion signal for output to a user.

A noise suppressor includes a memory; and a processor coupled to the memory, the processor is configured to: acquire a noise signal in a vicinity of a head region of an occupant seated in a vehicle seat; generate a control sound having an opposite phase to the acquired noise signal; acquire a sound signal having a predetermined frequency that is different from the noise signal; and output, as an output sound signal, the acquired sound signal in combination with the generated control sound.