A method for feedforward noise cancellation in an enclosed space within a structure is provided. The method comprises placing a microphone array inside an inner surface of the enclosed space and conducting modal testing on an outside surface of the enclosed space, wherein the modal testing comprises multiple incoherent noise sources corresponding to locations of microphones in the microphone array. Noise generated by the modal testing is processed to create a number of acoustic mathematical models of the enclosed space. In response to incoherent noise within the enclosed space, a noise canceling signal is generated according to an output of the mathematical models.

A headset with automatic noise reduction mode switching is provided to enable better call experience when conducting a call. The headset comprises at least one or more earphones, one or more microphones, a processor, and an active noise cancellation circuit, connected at least with the processor. The processor is configured to determine whether a call is being conducted using the headset, and if a call is being conducted, to switch the active noise cancellation circuit from a first ANC mode to a second ANC mode.

In an active noise reducing headphone, a signal processor applies filters and control gains of both the feed-forward and feedback active noise cancellation signal paths. The signal processor is configured to apply first feed-forward filters to the feed-forward signal path and apply first feedback filters to the feedback signal path during a first operating mode providing effective cancellation of ambient sound, and to apply second feed-forward filters to the feed-forward signal path during a second operating mode providing active hear-through of ambient sounds with ambient naturalness.

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.

To reduce engine noise in the cabin of an aircraft a plurality of error microphones is deployed at predetermined locations within the cabin to produce error microphone response signals associated with the engine noise in the cabin. Engine vibration inputs are obtained from sensors coupled to the aircraft engines. A processor is used to code the error microphone response signals into an encoded modal response in the cabin through a coding matrix. A processor is used to apply an adaptive filter to determine a plurality of modal signals needed to cancel the encoded modal response in the cabin. A processor is used to decode the modal signals into speaker input signals through a decoding matrix. Speaker input signals are then sent to a plurality of speakers to reduce the engine noise in the cabin.

Provided is a signal processing apparatus of a plurality of signal processing apparatuses that includes a noise canceling processing unit capable of connecting one or more input portions and one or more output portions, and performs a noise canceling processing. Signal processing apparatuses of the plurality of signal processing apparatuses are connected to one another.

Provided is an information processor including a signal processing section that acquires a first signal to be detected by an acoustic input section of a first unit including the acoustic input section disposed within a predetermined distance from one ear hole of a user in a state of being worn by the user, acquires a second signal, which indicates a noise generated from a noise source, to be acquired by a second unit, and generates a noise cancellation signal directed to the noise on the basis of the first signal and the second signal.

A sound reproducing apparatus includes a speaker, a microphone, and at least one processor. The at least one processor performs a process that includes hear-through processing and noise cancellation processing. The process also includes a storage task and a reading task. When detecting an occurrence of the trigger, the reading task reads control information of the event information of which execution is instructed by the trigger. The reading task also executes the hear-through processing and the noise cancellation processing in the signal processing task.

An active noise reduction system includes a canceling sound output device configured to output a canceling sound for canceling a noise, a noise signal generator configured to generate noise signals based on the noise, and a controller configured to control the canceling sound output device based on the noise signals, wherein the controller is configured to acquire buffer data in which the noise signals are stored in a time series, generate a plurality of divided data by dividing the buffer data, calculate a correlation value of the buffer data based on the plurality of divided data, detect presence/absence of disturbance mixed in the buffer data based on the correlation value, and switch control over the canceling sound output device according to the presence/absence of the disturbance mixed in the buffer data.

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.