Noise reduction method and apparatus utilizing filtering of a dithered signal

摘要

A noise reducing method and apparatus for reducing quantization error or noise generated on quantizing input signals, such as digital audio signals, wherein a dither signal concentrated in signal energy in the low frequency range is summed to the input signal and the resulting sum signal is sent to a quantizer. The quantizer error generated in the quantizer is fed back via a noise filter to the input side of the quantizer. The resulting signal has a smoothed noise floor and has noise components suppressed in a frequency range to which the human hearing mechanism exhibits high sensitivity, thus realizing the sound quality comparable to that of the input signal which prevailed prior to noise shaping.