| 摘要 |
PURPOSE:To prevent cut-off frequency for determining a band limit from being varied virtually contrary to the expectation due to a variation of the boosting quantity. CONSTITUTION:In the band boosting circuit for controlling the gain of a gain control circuit 4 connected to a post-stage of a band limiting filter circuit 2 in accordance with a level of a signal obtained by detecting an output signal of the band limiting filter circuit 2 to which an audio signal is inputted, and adding an output signal of the gain control circuit 4 to an input signal, this circuit is constituted by connecting a variable filter circuit 7 in which a cut-off frequency is varied in accordance with a level of a detecting signal, between the band limiting filter circuit 2 and the gain control circuit 4. |
