Method and device forr emphasizing pitch

Abstract

LPC inverse filter 301 calculates a residual signal from a decoded speech and then first lag value calculator 302 obtains first lag value T1 using residual signal r(n). Then, second lag value calculator 303 calculates second lag value T2. Second lag value T2 is calculated as a lag value corresponding to a maximum value of a correlation value of the residual signal or related value within the range centered on first lag value T1 or a lag value twice first lag value T1 or its integer part including fractional lag values before and after that lag value. The pitch weighting filter is applied to the decoded speech by using the signal waveform corresponding to the first and second lag values.

Description

technical field [0001] The present invention relates to a method and apparatus for pitch enhancement in a speech decoder included on a digital speech communication device, such as a digital cellular telephone. Background technique [0002] Conventional digital cellular phones and the like contain speech coders / decoders to efficiently compress and transmit speech signal information. The speech decoder performs post-filtering to improve the perceptual quality and prevent the degradation of the decoded speech quality caused by encoding. Post-filtering includes pitch enhancement for improving perceptual quality by enhancing the pitch periodicity of the decoded signal. A traditional tone enhancement method is based on the technology recommended by the international organization ITU-T G729 (8 kbps CS-ACELP speech coding method). Use below figure 1 with figure 2 To illustrate this traditional pitch enhancement method. [0003] figure 1 is a block diagram of the structure of ...

AI Technical Summary

Problems solved by technology

[0010] However, the problem with simply increasing the constant γ is that it deteriorates the naturalness of the speech, and worse, the perceptual quality

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