A speaker system uses destructive wave interference to generate “dead spots” with respect to an audio presentation. The signal for the dead spot generating device can be an inverted signal generated using the audio signal. In one embodiment, the inverted signal is generated using the audio signal, an indication of loudness at one or more active speakers, and a determination of the characteristics of the sound path from the one or more active speakers (including delay and attenuation).

A refuse vehicle includes a body coupled at least one of the frame and the chassis, a battery configured to provide electrical power to a first motor, a vehicle body supported by the chassis and defining a receptacle for storing refuse therein, an electric power take-off system coupled to the vehicle body, the electric power take-off system including a second motor configured to convert electrical power received from the battery into hydraulic power, one or more microphones coupled to the body and configured to detect noise, one or more speakers coupled to the body configured to emit noise reducing sounds, and a controller configured to receive data related to the detected noise from the one or more microphones and cause the one or more speakers to emit the noise reducing sounds in response to the data received from the one or more microphones.

A respiratory mask system is presented. This respiratory mask system includes an inflatable harness and a bone conduction device to provide audio to a user while wearing the respiratory mask system. The bone conduction device is installed on or interconnected with a portion of the inflatable harness, such as a tube of the inflatable harness that is positioned at least somewhat in proximate to a user's ear. Inflation of the inflatable harness may press the bone conduction device against the user to enhance the delivery of audio to the user.

Embodiments of the present disclosure disclose an earphone including a fixing structure, a first microphone array, a processor, and a speaker. The fixing structure is configured to fix the earphone near a user's ear without blocking the user's ear canal and including a hook-shaped component and a body part. The first microphone array is located in the body part and is configured to pick up environmental noise. The processor is located in the hook-shaped component or the body part and is configured to estimate a sound field at a target spatial position using the first microphone array and generate a noise reduction signal based on the estimated sound field. The target spatial position is closer to the user's ear canal than any microphone in the first microphone array. The speaker is located in the body part and is configured to output a target signal according to the noise reduction signal.

The present disclosure provides a method and an apparatus for noise reduction, and a headset. The method of noise reduction includes: acquiring a first reference noise signal; acquiring an initial direction of desired speech in response to a trigger signal; acquiring a real-time direction of desired speech based on a real-time orientation of the headset and the initial direction of desired speech, the real-time orientation being obtained by orientation tracking for the headset; filtering out a desired speech signal from the first reference noise signal to acquire an undesired noise signal, the desired speech signal being extracted in the real-time direction of desired speech; and filtering the undesired noise signal to output an inverse noise signal for speaker playback. Thus, using the method of noise reduction, not only the undesired noise in the ambient noise can be cancelled, but also the desired speech signal can be retained.

A processor is configured to perform headphone playback with a playback audio signal. The processor produces a feedback signal from an internal microphone, compresses the feedback signal according to a variable compressor setting, and determines a context of usage of the headphone, as being one of running or jogging, transportation, and critical listening. In response, the processor changes the variable compressor setting and drives the headphone speaker with the compressed feedback signal combined with the playback audio signal. Other aspects are also described and claimed.

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.

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.

An integrated circuit may include an output for providing an output signal to a transducer including both a source audio signal for playback to a listener and an anti-noise signal for countering the effect of ambient audio sounds in an acoustic output of the transducer, an error microphone input for receiving an error microphone signal indicative of the output of the transducer and the ambient audio sounds at the transducer, and a processing circuit. The processing circuit may implement a feedback path comprising a feedback filter having a response that generates a feedback anti-noise signal based on the error microphone signal, the feedback filter comprising a plurality of biquad filters and wherein the anti-noise signal is generated from the feedback anti-noise signal and an event detection and oversight control that detects that an ambient audio event is occurring that could cause the feedback filter to generate an undesirable component in the anti-noise signal, and controls filter coefficients of one or more of the plurality of biquad filters to reduce the undesirable component.