Noise abatement within a signal stream containing unwanted signal referred to as noise is performed by acquiring a digitized noise signal and using a digital processor circuit to subdivide the acquired noise signal into different frequency band segments and thereby generate a plurality of segmented noise signals. Then individually for each segmented noise signal, the processor shifts in time the segmented noise signal by an amount dependent on a selected frequency of the segmented noise signal to produce a plurality of shifted segmented noise signals. The precise time shift applied to each noise segment considers the frequency content of the segment and the system processing time. Individually for each segmented noise signal, amplitude scaling is applied. The shifted and amplitude-scaled segmented noise signals are then combined to form a composite anti-noise signal which is output into the signal stream to abate the noise through destructive interference.

An earpiece includes a feed-forward microphone coupled to the environment outside the headphones, a feedback microphone coupled to an ear canal of a user when the earpiece is in use, a speaker coupled to the ear canal of the user when the earpiece is in use, a digital signal processor implementing feed-forward and feedback noise compensation filters between the respective microphones and the speaker, and a memory storing an ordered sequence of sets of filters for use by the digital signal processor. Each of the sets of filters includes a feed-forward filter that provides a different frequency-dependent amount of sound pass-through or cancellation, which in combination with residual ambient sound reaching the ear results in a total insertion gain at the ear of a user.

A sound-modulating device used in a confined space is provided. The sound-modulating device includes an event detector and an audio module in communication with each other. The event detector detects an event and generates a trigger signal in response to the detected event. The audio module plays a music segment in response to the trigger signal. The frequencies of the music segment range from 20 Hz to 20000 Hz. The intensities of the music segment are smaller than or equal to 75 dB.

An earpiece includes a feed-forward microphone coupled to the environment outside the headphones, a feedback microphone coupled to an ear canal of a user when the earpiece is in use, a speaker coupled to the ear canal of the user when the earpiece is in use, a digital signal processor implementing feed-forward and feedback noise compensation filters between the respective microphones and the speaker, and a memory storing an ordered sequence of sets of filters for use by the digital signal processor. Each of the sets of filters includes a feed-forward filter that provides a different frequency-dependent amount of sound pass-through or cancellation, which in combination with residual ambient sound reaching the ear results in a total insertion gain at the ear of a user.

A vehicle includes a music signal processing system having a loudspeaker disposed within a passenger compartment of the vehicle and emitting audible music into the passenger compartment. A microphone is disposed within the passenger compartment and converts the audible music and noise within the passenger compartment into an analog electrical microphone signal. An analog-to-digital converter is connected to an output of the microphone and receives the analog electrical microphone signal and converts the analog electrical microphone signal into a digital electrical microphone signal. A sample rate down converter is connected to an output of the analog-to-digital converter. A narrow band adaptive noise control is connected to an output of the sample rate down converter and receives an engine speed signal. A sample rate up converter is connected to an output of the narrow band adaptive noise control. An adder device adds an output of the sample rate up converter to a music signal. A digital-to-analog converter is connected to an output of the adder device. An amplifier has an input connected to an output of the digital-to-analog converter. An output of the amplifier is connected to an input of the loudspeaker.

A personal audio device, such as a wireless telephone, includes noise canceling that adaptively generates an anti-noise signal from a reference microphone signal and injects the anti-noise signal into the speaker or other transducer output to cause cancellation of ambient audio sounds. An error microphone is provided proximate the speaker to measure the output of the transducer in order to control the adaptation of the anti-noise signal and to estimate an electro-acoustical path from the noise canceling circuit through the transducer. The anti-noise signal is adaptively generated to minimize the ambient audio sounds at the error microphone. A processing circuit that performs the adaptive noise canceling (ANC) function also filters one or both of the reference and/or error microphone signals, to bias the adaptation of the adaptive filter in one or more frequency regions to alter a degree of the minimization of the ambient audio sounds at the error microphone.

An open wearable acoustic device and an active noise reduction method are provided. The acoustic device includes a first sound sensor module, a speaker, and a noise reduction circuit. The noise reduction circuit may obtain a first sound signal from the first sound sensor module, select a target noise reduction mode from a plurality of noise reduction modes based on the first sound signal, and execute the target noise reduction mode. This solution can adaptively adjust a noise reduction mode based on a noise condition of an external environment of the acoustic device, so that an active noise reduction process of the acoustic device is more in line with the noise condition of a current environment, thereby improving a noise reduction effect of the acoustic device.

An earpiece includes a feed-forward microphone coupled to the environment outside the headphones, a feedback microphone coupled to an ear canal of a user when the earpiece is in use, a speaker coupled to the ear canal of the user when the earpiece is in use, a digital signal processor implementing feed-forward and feedback noise compensation filters between the respective microphones and the speaker, and a memory storing an ordered sequence of sets of filters for use by the digital signal processor. Each of the sets of filters includes a feed-forward filter that provides a different frequency-dependent amount of sound pass-through or cancellation, which in combination with residual ambient sound reaching the ear results in a total insertion gain at the ear of a user.

A vehicle includes a music signal processing system having a loudspeaker disposed within a passenger compartment of the vehicle and emitting audible music into the passenger compartment. A microphone is disposed within the passenger compartment and converts the audible music and noise within the passenger compartment into an analog electrical microphone signal. An analog-to-digital converter is connected to an output of the microphone and receives the analog electrical microphone signal and converts the analog electrical microphone signal into a digital electrical microphone signal. A sample rate down converter is connected to an output of the analog-to-digital converter. A narrow band adaptive noise control is connected to an output of the sample rate down converter and receives an engine speed signal. A sample rate up converter is connected to an output of the narrow band adaptive noise control. An adder device adds an output of the sample rate up converter to a music signal. A digital-to-analog converter is connected to an output of the adder device. An amplifier has an input connected to an output of the digital-to-analog converter. An output of the amplifier is connected to an input of the loudspeaker.

An indoor sound-modulating device is provided. The indoor sound-modulating device includes a low-frequency noise detector, an automatic actuator and an audio signal generator. The low-frequency noise detector detects low-frequency noise and generates a first modulating signal in response to the detected low-frequency noise. The automatic actuator issues a second modulating signal in response to a predetermined state. The audio signal generator generates a low-frequency audio signal for eliminating the low-frequency noise in response to the first modulating signal and generates a high-frequency repellent audio signal in response to the second modulating signal. The low-frequency audio signal has a frequency ranging from 20 Hz to 350 Hz, while the high-frequency repellent audio signal has a frequency not less than 8000 Hz.