| 摘要 |
PURPOSE:To obtain a sound quality to be always equal and to be more natural even when a sound volume is changed by automatically executing the loudness compensation of low and high sound bands not only at the time of a small sound volume but also at the time of a large sound volume. CONSTITUTION:For one side of stereo signals to be divided into two, intermediate and high sound bands are extracted through HPFs 11 and 11', and the signal is inputted to sound volume adjusting volumes 13 and 13'. The gradient and cut-off frequency fc1 of the HPFs 11 and 11' are made into 12dB/oct and approximately 300Hz-500Hz. At such a time the other side is made into a monaural signal by an addition 14, a low sound band is extracted by a BPF 15, and the signal is inputted to an intermediate tap (c) of the sound volume adjusting volumes 13 and 13'. The gradient and cut-off frequency fc21 of the BPF 15 are made into -12dB/oct and approximately 70Hz-150Hz. While the other gradient exists, in order to cause an automobile room sound field correction to be sufficiently effective, the gradient may as well be -12dB/oct or above. |
