| 摘要 |
PROBLEM TO BE SOLVED: To provide an in-cabin frequency characteristic automatic correction system in which a frequency characteristic balance natural in auditory feeling is obtained by applying various conversion to signals obtained from a microphone so as to calculate phase difference characteristics of left and right ears and correcting the characteristics based on frequencies band where the left and right ears are not opposite in phase to each other. SOLUTION: Microphones 41, 42 receive sounds from speakers 31-34 and their signals are fed to an A/D converter 23 and a frequency characteristic arithmetic section 13. The arithmetic section 13 converts the signal into an impulse response. High speed Fourier transform is applied to the impulse response and frequency characteristics for left and right ears are calculated and a phase characteristic and a phase difference characteristic are calculated from them. A inverted band where the phases are opposite is searched from the phase difference characteristic. In this band, a boost correction to increase the gain of an equalizer section 12 for in-cabin characteristic correction is not conducted. A frequency for a correction point is decided for the band where phases are not opposite and a parameter of the correction equalizer section 12 is set based on the frequency and the frequency characteristic is automatically corrected. |
