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.

Embodiments of this application disclose a noise cancellation apparatus and method. The noise cancellation apparatus includes a main control unit and a noise cancellation processing circuit. The main control unit determines a noise cancellation parameter based on a noise cancellation level index or a feature value for determining a matching degree between a headset and an ear canal of a user. The noise cancellation processing unit obtains an inverse phase noise of an ambient noise based on the noise cancellation parameter. After the inverse phase noise is mixed with a played downlink audio signal, the ambient noise can be canceled. In addition, because the noise cancellation parameter is determined from a preset noise cancellation parameter library based on the received or autonomously determined noise cancellation level index, instead of being uniformly configured, a noise cancellation level can be flexibly adjusted, thereby improving a noise cancellation effect and user experience.

An active noise cancellation (ANC) system has a mounting plate, a first face of which is configured to be disposed against an inner surface of a helmet to form, with the helmet, a chamber. When the mounting plate is mounted on the helmet, a loudspeaker provided on the first face of the mounting plate is within the chamber. The plate has an aperture for allowing transmission of sound from the loudspeaker to the spatial region. At least one reference microphone is mounted on a second face of the plate. The plate acts as a mounting plate for components of the ANC system, simplifying the process of installing an ANC system. Also, the plate serves to define a chamber that accommodates the loudspeaker of the ANC system and provides good acoustic coupling of the sound signal from the loudspeaker of the ANC system into the quiet zone of the ANC system.

An active noise control (ANC) circuit is used for generating an anti-noise signal, and has a plurality of filters including at least one first filter and at least one second filter. The at least one first filter generates at least one first filter output, wherein each of the at least one first filter has a first filter type. The at least one second filter generates at least one second filter output, wherein each of the at least one second filter has a second filter type different from the first filter type. The anti-noise signal is jointly controlled by the at least one first filter output and the at least one second filter output. The at least one first filter and the at least one second filter are connected in a parallel fashion.

An ear-wearable device is operable to receive a reference signal from outside an ear canal of a user and an error signal from inside of the ear canal. A physical propagation path between the outside and inside of the ear canal defines a primary path, and amplified sound produced inside of the ear canal propagates over a secondary path to combine with direct noise at the ear canal. A noise signal inside the ear canal is estimated from the reference signal based on estimate of the primary and secondary paths. The estimated noise signal and the error signal are used to produce coefficients of an adaptive filter. The adaptive filter is used to produce an anti-noise signal, which is used actively cancel noise in the ear canal.

An open acoustic device (100) may include a fixing structure (120) configured to fix the acoustic device (100) near an ear of a user without blocking an ear canal of the user; a first microphone array (130) configured to acquire environmental noise (410); a signal processor (140) configured to: determine, based on the environmental noise, a primary route transfer function (420) between the first microphone array (130) and the ear canal of the user; estimate, based on the environmental noise and the primary route transfer function, a noise signal (430) at the ear canal of the user; and generate, based on the noise signal at the ear canal of the user, a noise reduction signal (440); and a speaker (150) configured to output, according to the noise reduction signal, a noise reduction acoustic wave (450), the noise reduction acoustic wave being configured to eliminate the noise signal.

An active noise reduction system includes a reference signal generator configured to generate a reference signal, a canceling sound generator configured to generate a canceling sound, an error detector configured to detect an error between a noise and the canceling sound and generate an error signal corresponding to the error, and a controller configured to control the canceling sound generator based on the reference signal and the error signal, wherein the controller is configured to update an estimation value of acoustic characteristics in an internal space of a mobile body based on the reference signal and the error signal, estimate a head position of an occupant in the internal space based on the updated estimation value of the acoustic characteristics, and update a control filter based on the estimated head position of the occupant, the control filter being a filter for controlling the canceling sound generator.

In the method according to the invention for active noise suppression, a transfer function for a secondary path between a loudspeaker and an error microphone is measured (20). Based on the measured transfer function for the secondary path, a transfer function for a primary path between a reference microphone and the error microphone is estimated (21). Based on the estimated transfer function for the primary path, filter coefficients for filtering to generate the cancellation signal are then determined (22).

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 waves and higher-frequency audio waves. The audio may be selected via a master control unit (MCU), which may be operatively coupled to a mobile application. In some 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.

An active control method for filtered reference affine projection sign algorithm based on variable step size includes: S1, acquiring impulse noise signals and transmitting the signals to control filters; S2, transmitting the impulse noise signals by the control filters to post filters; S3, generating cancellation signals of the impulse noise signals by the post filters according to the impulse noise signals and internal active control algorithms, and transmitting the cancellation signals to a speaker; S4, sending out the cancellation signal by the speaker to superimpose with the impulse noise signals to cancel the impulse noise signal. A convex combination structure and a variable step size strategy are adopted, and by adjusting step size coefficients in the control filter structure, convergence speed of algorithm is controlled, contradiction between convergence speed and steady-state error is coordinated, convergence performance of control algorithm to impulse noises is improved, and impulse noises are effectively controlled.