The present invention is in the field of an active sound-cancellation system, an open fluid-duct comprising such an active sound-cancellation system, such as an air duct, and an active sound-cancellation computer program comprising instructions for operating such an active sound-cancellation system. The active sound-cancellation system reduces noise significantly.

An active noise canceller device includes: a reference signal generation device, generating a reference signal corresponding to a noise; a cancellation sound output device, outputting cancellation sound for canceling the noise; an error detection device, detecting an error between the noise and the cancellation sound and generating an error signal corresponding to the error; and a control device, controlling the cancellation sound output device that further including: a reference signal correction part, correcting the reference signal; a noise estimation part, estimating a sound pressure; a sound pressure estimation part, estimating the sound pressure within an object range of the cancellation sound that cancels the noise; and a control filter, controlling the cancellation sound. The active noise canceller device updates the control filter based on the reference signal corrected by the reference signal correction part and a sound pressure estimated value of the sound pressure estimation part.

A sound control device mounted in a vehicle and control method include measuring a drive signal input to a speaker, wherein the drive signal is generated in response to an input signal including at least one of a noise control signal and an audio signal, estimating a state of a voice coil of the speaker including at least one of displacement and temperature of the voice coil, based on the drive signal and a model of the speaker, and adjusting the input signal based on the state of the voice coil.

There is described a computer-implemented method for calibrating a sound signal, comprising: receiving an initial sound signal, a recorded background sound signal, a recorded initial sound signal and a target sound signal; subtracting the recorded background sound signal from the recorded initial sound signal, thereby obtaining a denoised sound signal; dividing the target sound signal by the denoised sound signal, thereby obtaining a compensation factor; dividing the initial sound signal by the compensation factor, thereby obtaining a calibrated sound signal; and outputting the calibrated sound signal.

An active noise cancellation device for cancelling a primary acoustic path between a noise source and a microphone by an overlying secondary acoustic path between a canceling loudspeaker and the microphone, the device comprising: a first input for receiving a microphone signal from the microphone; wherein the first electrical compensation path and the second electrical compensation path are coupled in parallel between a first node and the first input to provide the first noise canceling signal for a feed-backward prediction of the noise source; wherein the third electrical compensation path and the fourth electrical compensation path are coupled in parallel between a second node and the first input to provide the second noise canceling signal for a feed-forward prediction of noise source.

A noise-reduction control method includes performing frequency-domain weighting and temporal-domain weighting to a noise signal collected at current time to obtain a weighted energy. Judging whether active noise-reduction control is needed based on the weighted energy; calculating an energy value of a first sub-band and an energy value of a second sub-band of the noise signal collected by the feedforward microphone at the current time, wherein the first sub-band and the second sub-band are determined based on a feedforward noise-reduction curve and a feedback noise-reduction curve of the earphone, respectively. Determining a feedforward noise-reduction amount and a feedback noise-reduction amount based on the energy value of the first sub-band and the energy value of the second sub-band, respectively. Controlling the earphone to perform feedforward noise reduction based on the feedforward noise-reduction amount, and controlling the earphone to perform feedback noise reduction based on the feedback noise-reduction amount.

An active noise control system for reducing the sound pressure level in one or more head areas of one or more seats in the interior of an aircraft fuselage includes multiple accelerometers mounted outside of the aircraft fuselage at or near the mounts of the aircraft's propulsion system. One or more loudspeakers are mounted at the seat and are responsible for the reduction of noise at its head area. The accelerometers continuously measure multiple reference signals during operation of the aircraft and report to a controller that continuously calculates the reported noise signals in the head areas based on the measured reference signals and its counter signals, which equal the amplitude but having opposite phase of the calculated arriving noise signals in each head area. The controller operates one or more actuator systems for continuously generating the counter signals.

The sound suppression apparatus comprises a sound sensing device, configured to sense a sound; and a sound producing device comprising an air-pulse generating device, configured to generate a plurality of air pulses at an ultrasonic pulse rate. The plurality of air pulses at the ultrasonic pulse rate forms an anti-sound. The anti-sound comprises a component which is configured to suppress the sound.

A web-based virtual meeting platform with echo suppression functionality that is hardware agnostic. The platform is configured in a client-server distributed architecture, wherein a plurality of user devices are connected to a server. A baseline for audio generated by a user device on the client-side of the client-server platform is established. Upon detection of a deviation from the baseline, including electro acoustic feedback and ambient noise, suppressive gain is applied to the audio input at the client-side of the client-server architecture. The suppressed audio stream is then transmitted to a cloud server and distributed to a plurality of user devices connected to the cloud service. The platform is accessible via an internet browser and is non-discriminatory as to the hardware of the device used to access the platform. Further, the platform does not distribute data in a peer-to-peer architecture.

A noise canceling adaptive filter outputs, from a front seat speaker, a noise canceling sound generated by applying a transfer function X(z) adapted by an adaptive operation using an output of a front seat microphone as an error to an output sound of a sound source apparatus. An output of the front seat microphone is added to an output of an audio feedback canceling filter by a second adder, added to an output sound of the sound source apparatus by a third adder, and output from a rear seat speaker. The audio feedback canceling filter applies a transfer function X(z) and a transfer function C{circumflex over ()}(z) on an output of the second adder and outputs a resultant. The transfer function C{circumflex over ()}(z) corresponds to a transfer function C(z) from the front seat speaker to the front seat microphone. In synchronization control, the transfer function X(z) is set as the transfer function X(z).