Audio signal processing device and remote control system
An audio signal processing device generates an output signal by alleviating a noise component in an input signal including both a sound component to be heard and the noise component. The audio signal processing device includes: a composite sound output part to output a composite sound signal; an adaptive filter to receive as an input the composite sound signal output from the composite sound output part; and a subtraction part to output an output sound signal by subtracting an output signal of the adaptive filter from an input sound signal. The adaptive filter performs adaptation operation assuming that the output sound signal from the subtraction part is an error. The composite sound signal from the composite sound output part is formed with pure tones of multiple frequencies extracted from a frequency band that is to be cancelled and that includes a frequency band of the alleviated noise component.
1 . A remote control system comprising:
an audio signal processing device for generating an output sound signal by alleviating a noise component in an input sound signal that includes both a sound component to be heard and the noise component, the audio signal processing device comprising:
a sound source device configured to output a composite sound signal;
an adaptive filter configured to receive as an input the composite sound signal output from the sound source device to output an adapted output signal; and
a subtractor configured to output the output sound signal by subtracting the adapted output signal of the adaptive filter from the input sound signal,
wherein the adaptive filter configured to perform an adaptation operation assuming that the output sound signal output from the subtractor is an error, and
wherein the composite sound signal output from the sound source device is formed with pure tones of a plurality of frequencies extracted from a frequency band that is to be cancelled and that includes a frequency band of the noise component alleviated in the audio signal processing device,
wherein the remote control system further comprises:
a vehicle system installed in a vehicle; and
a control system configured to control the vehicle remotely,
wherein the vehicle system includes:
a microphone configured to pick up a sound in which a sound to be heard and noise are mixed, and output a monitoring sound signal; and
a transmitter configured to transmit the monitoring sound signal output from the microphone to the control system, wherein the control system includes:
a receiver configured to receive the monitoring sound signal from the vehicle system;
a speaker; and
the audio signal processing device, and
wherein the monitoring sound signal received by the receiver is input to the audio signal processing device as the input sound signal, and the output sound signal is output from the audio signal processing device to the speaker.
2 . The remote control system according to claim 1 , wherein the composite sound signal output from the sound source device is formed with the pure tones of the plurality of frequencies extracted from the frequency band to be cancelled at predetermined frequency intervals.
3 . The remote control system according to claim 1 , further comprising:
a storage device configured to store frequency-domain information of the composite sound signal to be output; and
a conversion circuit configured to convert the frequency-domain information stored in the storage device into the composite sound signal.
4 . The remote control system according to claim 3 ,
wherein the frequency-domain information of the composite sound signal is a Fourier coefficient, and
wherein the conversion circuit is an inverse fast Fourier transform circuit configured to convert the frequency-domain information into the composite sound signal using an inverse fast Fourier transform.
5 . The remote control system according to claim 3 ,
wherein the frequency-domain information of the composite sound signal is a wavelet transform coefficient, and
wherein the conversion circuit is an inverse wavelet transform circuit configured to convert the frequency-domain information into the composite sound signal using an inverse wavelet transform.
6 . A remote control system comprising:
an audio signal processing device for generating an output sound signal by alleviating a noise component in an input sound signal including both a sound component to be heard and the noise component, the audio signal processing device comprising:
a first conversion circuit configured to convert the input sound signal into first information, the first information being frequency-domain information of the input sound signal;
a storage device configured to store second information, the second information being frequency-domain information of a composite sound signal formed with pure tones of a plurality of frequencies extracted from a frequency band that is to be cancelled and that includes a frequency band of the noise component alleviated in the audio signal processing device;
an adaptive filter configured to receive the second information as an input and output third information as an adapted output signal, the third information being frequency-domain information of a noise-canceling sound;
a subtractor configured to output fourth information, the fourth information being frequency-domain information obtained by subtracting the third information from the first information; and
a second conversion circuit configured to convert the fourth information into a sound signal and output the sound signal as the output sound signal,
wherein the adaptive filter is configured to perform an adaptation operation assuming that the fourth information is an error,
wherein said remote control system further comprises:
a vehicle system installed in a vehicle; and
a control system configured to control the vehicle remotely,
wherein the vehicle system includes:
a microphone configured to pick up a sound in which a sound to be heard and noise are mixed, and output a monitoring sound signal; and
a transmitter configured to transmit the monitoring sound signal output from the microphone to the control system,
wherein the control system includes:
a receiver configured to receive the monitoring sound signal from the vehicle system;
a speaker; and
the audio signal processing device, and
wherein the monitoring sound signal received by the receiver is input to the audio signal processing device as the input sound signal, and the output sound signal is output from the audio signal processing device to the speaker.
7 . The remote control system according to claim 6 , wherein the composite sound signal is formed with the pure tones of the plurality of frequencies extracted at predetermined frequency intervals from the frequency band to be cancelled.
8 . The remote control system according to claim 6 ,
wherein the frequency-domain information is a Fourier coefficient,
wherein the first conversion circuit is a fast Fourier transform circuit configured to convert the input sound signal into the first information by performing a fast Fourier transform, and
wherein the second conversion circuit is an inverse fast Fourier transform circuit configured to convert the fourth information into the output sound signal by performing an inverse fast Fourier transform.
9 . The remote control system according to claim 6 ,
wherein the frequency-domain information is a wavelet transform coefficient,
wherein the first conversion circuit is a wavelet transform circuit part configured to convert the input sound signal into the first information by performing a wavelet transform, and
wherein the second conversion circuit is an inverse wavelet transform circuit part is configured to convert the fourth information into the output sound signal by performing an inverse wavelet transform.