A feedforward ambient noise reduction arrangement includes, within a housing, a loudspeaker device for directing sound energy into an ear of a listener. Disposed externally of the housing, and positioned to sense ambient noise on its way to the listener's ear, are plural microphone devices capable of converting the sensed ambient noise into electrical signals for application to the loudspeaker to generate an acoustic signal opposing the ambient noise. Importantly, the overall arrangement is such that the acoustic signal is generated by said loudspeaker means in substantial time alignment with the arrival of said ambient noise at the listener's ear.

A method for providing directed transmission of sound waves, through modulation on an ultrasonic carrier, may comprise connecting, at least one directed sound source to an audio system, emitting, via the at least one directed sound source, audio from the audio system, wherein the emitting comprises emitting medium frequency audio sound waves and higher frequency audio sound waves. The audio may be selected via a master control unit, which may be operatively coupled to a mobile application. In many embodiments, a first audio selection is configured to be heard only through a first directed sound source, and a second audio selection is configured to be heard only through a second directed sound source.

Audio pickup systems and methods are provided to enhance an audio signal by removing noise components related to an acoustic environment. The systems and methods receive a primary signal and one or more reference signals from various microphones. Adaptive filtering and combining minimizes an energy content of a resulting output signal, e.g., to form a substantially null output when the system is in a static acoustic environment. When the system is a playback sound source, one or more echo cancellers may contribute to removing content from the output signal. A change in the acoustic environment, such as a new sound source, causes content in the output signal until the adaptive filtering adapts to the new environment. In some examples, a desired content such as a wake-up word is detected and adaptation is stopped.

A method may include adaptively generating an anti-noise signal for countering the effects of ambient audio sounds at an acoustic output of the transducer by adapting a response of an adaptive filter that filters a reference microphone signal in conformity with an error microphone signal and the reference microphone signal to minimize the ambient audio sounds in the error microphone, generating a scaled anti-noise signal by applying a scaling factor to the anti-noise signal, further adjusting the response of the adaptive filter independent of a source audio signal by altering an input to the coefficient control block of the adaptive filter to compensate for the scaling factor, and combining the scaled anti-noise signal with the source audio signal to generate an audio signal provided to the transducer.

An active noise control device performs signal processing on a basic signal corresponding to a control target frequency by a control filter, which is an adaptive notch filter, to generate a control signal that controls a speaker, sequentially and adaptively updates coefficients of the control filter, compares a magnitude of a primary path filter with a magnitude of the control filter, and determines whether the state of the control filter is unstable or not.

The driving device for providing assisted ventilation comprises an air inlet (15), an impeller (7) provided with blades (8) rotatably driven by a motor (6), and an air outlet (5), the rotation of said impeller (7) being caused by the air circulation through a duct (4) from the air inlet (15) to the air outlet (5), wherein said blades (8) of the impeller (7) are flexible, vibrating at least one of its ends by the thrust caused by said circulating air.

It reduces noise to improve user comfort.

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.

A feedforward ambient noise reduction arrangement includes, within a housing, a loudspeaker device for directing sound energy into an ear of a listener. Disposed externally of the housing, and positioned to sense ambient noise on its way to the listener's ear, are plural microphone devices capable of converting the sensed ambient noise into electrical signals for application to the loudspeaker to generate an acoustic signal opposing the ambient noise. Importantly, the overall arrangement is such that the acoustic signal is generated by said loudspeaker means in substantial time alignment with the arrival of said ambient noise at the listener's ear.

Audio systems, methods, and computer readable mediums having program code to receive a harmonic signal related to rotating equipment, such as a vehicle drivetrain in some examples, and provide a harmonic cancellation (or enhancement) signal. The harmonic cancellation signal is transduced into an acoustic signal, and a feedback sensor, such as a microphone, detects an error signal representative of acoustic energy at a first location in the environment. A projection filter filters the error signal to provide an estimated error signal at a second location in the environment, such as at the location of an occupant's ear(s). An adaptive module adjusts the cancellation signal based on the estimated error signal.

An active noise control apparatus of vehicles capable of making it difficult for a passenger in a vehicle to hear the voice of another passenger, achieving privacy protection, and a method of controlling the same are disclosed. The active noise control method includes primarily determining a noise level based on a first microphone signal input through a microphone corresponding to a first seat, secondarily determining whether to output an anti-noise signal generated based on the first microphone signal and the magnitude of the anti-noise signal based on the noise level and the level of the first microphone signal, and outputting the anti-noise signal through a headrest speaker of a second seat in response to the secondary determining.