| 摘要 |
PURPOSE:To implement proper amplification control free from digital clipping by minimizing the reduction of a dynamic range. CONSTITUTION:Filters 11a, 11b are used to extract a specific frequency band component of an input signal and variable amplifiers 12a, 12b amplify the extracted component at a multiple of K. On the other hand, attenuators 10a, 10b attenuate the input signal by a prescribed value; and adders 13a, 13b are used to add the attenuated signal and the amplified signal to the specific frequency band component respectively. The digital audio signal after the end of addition is fed to a level discrimination section 14, and an amplified quantity calculation section 15 increases/decreases the coefficient K with a negative constant A and a positive constant B based on the result of level discrimination. In this case, the controller is provided with a control means that limits the coefficient K within a range of a maximum value Kmax or below and a minimum value Kmin or over, and the added value to the adders 13a, 13b is changed depending on the coefficient K to adjust the amplified quantity. |
