Intelligibility improvement of bandlimited synthesized speech by superposing high frequency component of input signal on baseband signal

We propose a new speech intelligibility improvement method for bandlimited synthesized speech, which is based on superposing high-frequency component on lower frequency signal (i.e., baseband signal), where the high-frequency component is compressed in the frequency direction to be fitted on the superposing zone of the baseband signal. We applied the proposed method to Text to speech and conducted a subjective evaluation of synthesized speech. According to the result, the synthesized speech by the proposed method is preferred to that by a simple high frequency emphasis of baseband.