On Normalized MSE Analysis of Speech Fundamental Frequency in the Cochlear Implant-Like Spectrally Reduced Speech

In this paper, we present a quantitative study on the speech fundamental frequency (F0) of the cochlear implant-like spectrally reduced speech (SRS). The SRS was synthesized from the subband amplitude and frequency modulations (AM and FM) of original clean speech utterances selected from the TI-digits database. The SRS synthesis algorithm was derived from the frequency amplitude modulation encoding (FAME) strategy, proposed by Nie et al., 2005. The normalized mses (NMSEs), calculated between the F0 of the original clean speech and that of the SRSs, were analyzed. The NMSEs analysis of F0 revealed the greater F0 distortion in the AM-based SRS, which is the acoustic simulation of present-day cochlear implants, compared to the FAME-based SRS. This evidence supports the fact that current cochlear implant users have difficulty in the speaker recognition task as reported by Zeng et al., 2005. Further, the analysis results showed that it is better to keep the rapidly varying FM components to reduce the F0 distortion in the FAME-based SRS at low spectral resolution.