Abstract: An adaptive identification system, for identifying a propagation system characteristic by an adaptive filter, includes a signal generator that generates an identification input signal including a frequency component of an integer multiple of a fundamental frequency and having a periodicity satisfying a PE condition, a setting unit that sets moving average time to a fundamental period of the identification input signal, and an adaptive algorithm execution unit that uses a moving average value and a diagonal matrix to update a coefficient of the adaptive filter, the moving average value being obtained by calculating a moving average of a cross-correlation vector of a vector of the identification input signal and an observation signal with the moving average time, and the diagonal matrix being obtained by diagonalizing a matrix obtained by calculating a moving average of an autocorrelation matrix of the vector of the identification input signal with the moving average time.

Abstract: An active noise control unit generates a noise canceling sound of a single frequency that cancels engine sound heard by an occupant and outputs the noise canceling sound to a speaker through an amplifier. A second harmonic detector and a third harmonic detector detect a magnitude of a harmonic component of the noise canceling sound included in sound collected by a microphone. A controller controls a frequency of the noise canceling sound generated by the active noise control unit to a fundamental frequency of the engine sound based on a rotation frequency of the engine, and in addition, causes an output level control unit to control a level of the noise canceling sound to be output to the amplifier so that the level of the noise canceling sound becomes higher when the magnitude of the harmonic component exceeds a predetermined threshold value.

Abstract: An active noise control unit generates a noise canceling sound of a single frequency that cancels engine sound heard by an occupant and outputs the noise canceling sound to a speaker through an amplifier. A second harmonic detector and a third harmonic detector detect a magnitude of a harmonic component of the noise canceling sound included in sound collected by a microphone. A controller controls a frequency of the noise canceling sound generated by the active noise control unit to a fundamental frequency of the engine sound based on a rotation frequency of the engine, and in addition, causes an output level control unit to control a level of the noise canceling sound to be output to the amplifier so that the level of the noise canceling sound becomes higher when the magnitude of the harmonic component exceeds a predetermined threshold value.

Abstract: An acoustic characteristic measurement device includes a speaker configured to output an acoustic signal in which a watermark signal is embedded; a microphone configured to perform sound collection with respect to the acoustic signal output from the speaker in a predetermined listening position; and an acoustic characteristic measurement unit configured to determine an acoustic characteristic of an acoustic space from the speaker to the listening position, on the basis of the watermark signal embedded in the acoustic signal which is subjected to the sound collection by the microphone.

Abstract: An adaptive identification system, for identifying a propagation system characteristic by an adaptive filter, includes a signal generator that generates an identification input signal including a frequency component of an integer multiple of a fundamental frequency and having a periodicity satisfying a PE condition, a setting unit that sets moving average time to a fundamental period of the identification input signal, and an adaptive algorithm execution unit that uses a moving average value and a diagonal matrix to update a coefficient of the adaptive filter, the moving average value being obtained by calculating a moving average of a cross-correlation vector of a vector of the identification input signal and an observation signal with the moving average time, and the diagonal matrix being obtained by diagonalizing a matrix obtained by calculating a moving average of an autocorrelation matrix of the vector of the identification input signal with the moving average time.

Abstract: A failure detection device for detecting a failure of a sound generating device outputting a sound based on sound data from a speaker includes: an electronic watermark signal generating unit configured to generate an electronic watermark signal including collation data used for collation of whether or not a sound is output from the speaker; the speaker configured to output the electronic watermark signal as a sound; a microphone configured to collect the sound output from the speaker; a collation data detection unit configured to detect the collation data from the electronic watermark signal included in the sound collected by the microphone; and a failure determination unit configured to determine the presence or absence of the failure of the sound generating device by collating the collation data detected by the collation data detection unit with the collation data included in the electronic watermark signal.

Abstract: A failure detection device for detecting a failure of a sound generating device outputting a sound based on sound data from a speaker includes: an electronic watermark signal generating unit configured to generate an electronic watermark signal including collation data used for collation of whether or not a sound is output from the speaker; the speaker configured to output the electronic watermark signal as a sound; a microphone configured to collect the sound output from the speaker; a collation data detection unit configured to detect the collation data from the electronic watermark signal included in the sound collected by the microphone; and a failure determination unit configured to determine the presence or absence of the failure of the sound generating device by collating the collation data detected by the collation data detection unit with the collation data included in the electronic watermark signal.

Abstract: An acoustic characteristic measurement device includes a speaker configured to output an acoustic signal in which a watermark signal is embedded; a microphone configured to perform sound collection with respect to the acoustic signal output from the speaker in a predetermined listening position; and an acoustic characteristic measurement unit configured to determine an acoustic characteristic of an acoustic space from the speaker to the listening position, on the basis of the watermark signal embedded in the acoustic signal which is subjected to the sound collection by the microphone.

Abstract: An error path characteristic model correction control unit determines the deviation of the phase of an actual transfer function from the phase of an error path characteristic model, from a cross correlation between an error signal output from a microphone and a signal in which the error path characteristic model is applied to a noise cancellation sound to be output and a cross correlation between the error signal and a signal in which a transfer function having a phase characteristic deviating by +90 degrees from the phase characteristic of the error path characteristic model is applied to the noise cancellation sound. The error path characteristic model correction control unit then corrects the error path characteristic model so that the determined deviation is reduced to ±90 degrees.

Abstract: An error path characteristic model correction control unit determines the deviation of the phase of an actual transfer function from the phase of an error path characteristic model, from a cross correlation between an error signal output from a microphone and a signal in which the error path characteristic model is applied to a noise cancellation sound to be output and a cross correlation between the error signal and a signal in which a transfer function having a phase characteristic deviating by +90 degrees from the phase characteristic of the error path characteristic model is applied to the noise cancellation sound. The error path characteristic model correction control unit then corrects the error path characteristic model so that the determined deviation is reduced to ±90 degrees.