| 摘要 |
PURPOSE:To obtain a sound quality with fidelity to the sound quality desired by a manufacturer by applying compensation at listening of sound volume larger than a reference curve and for masking due to drive noise. CONSTITUTION:An input audio signal is given to a band pass filter(BPF) 20 and a band eliminate filter(BEF) 21, a middle sound frequency band is extracted by the BPF 20, and a low and high sound frequency bands are extracted and amplified by the BEF 21. The low and high sound frequency band components extracted and amplified by the BEF 21 are subject to logarithmic compression by a logarithmic compression amplifier 22, and a limiter circuit 23 gives attenuation of low and high sound frequency bands at a large sound volume higher than a reference curve. Moreover, a level difference between a reference noise compensation curve at idling and a reference noise compensation curve at the drive at 100km/h is present in advance in the compensation circuit as a compensation with respect to the mashing due to drive noise. Thus, the sound quality intended by the manufacturer is obtained with fidelity. |
