Filter for speech modification or enhancement, and various apparatus, systems and method using same

摘要

A speech modification or enhancement filter, and apparatus, system and method using the same. Synthesized speech signals are filtered to generate modified synthesized speech signals. From spectral information represented as a multi-dimensional vector, a filter coefficient is determined so as to ensure that formant characteristics of the modified synthesized speech signals are enhanced in comparison with those of the synthesized speech signal and in accordance with the spectral information. The spectral information can be any one of LSP information, PARCOR information and LAR information. A degree of freedom of design of the speech modification filter used for the aural suppression of quantizing noise contained in the synthesized speech signals is thus heightened leading to the improvement of intelligibility of said synthesized speech signals. A good formant enhancement effect can be obtained without allowing any perceptible level of distortions to occur within a range of permissible spectral gradients.