| 摘要 |
PURPOSE:To reduce the distortion in a hearing during a decoding by changing the quantization level when a sharp rise is detected in speech signals. CONSTITUTION:Digital speech signals Sp are supplied to a spectrum analyzer 1 being used as a frequency analysis means, a transient detector 5 being used as a rise detection means and a quantization level computer 7 being used as a quantization level computing means. When a transient is detected by the transient detector 5, a transient detection signal St is outputted to the quantization level computer 7 which is to be connected. The quantized level computed here are outputted to a quantizer 3, and quantized based on the quantized level outputted from the quantized level computer 7 in each spectrum outputted from the spectrum analyser 1. The quantized data, which are quantized and outputted, are multiplexed by a multiplexer 9 and outputted to a coding section as a bit stream Sb. |
