# Whispered Speech Conversion Based on the Inversion of Mel Frequency Cepstral Coefficient Features
## 2 Whispered Speech Conversion Process
### Inversion of Speech Features
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Conversion Method** & **Linear Predictive Coefficient (LPC)** & **DNN** & **MFCC** & **MFCCs** \\ \hline MOS mean & 3.02 & 3.22 & 3.45 & 3.56 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Comparison of the MOS scores for four methods. Figure 5: **(a)** Cepstral distances between normal speech with whispered speech and converted speeches using LPC, DNN, MFCC and MFCCs. **(b)** MOS with 95% confidence w.r.t LPC, DNN, MFCC and MFCCs. Figure 6: Spectrogram of the sentence “gu min sang shi xin” based on MFCC feature conversion: (**a**) whispered speech; (**b**) normal speech; (**c**) speech converted using LPC; (**d**) speech converted using DNN; (**e**) speech converted using MFCC; (**f**) speech converted using MFCCs. ## 4 Conclusions

To consider the sparseness of speech, we proposed to use the L1/2 algorithm to invert the MFCC features, which generates a good hearing effect. We used the GMM to jointly model the feature parameters of whispered speech and normal speech, we obtained a conversion model that converted whispered speech features to normal speech features, and lastly, we adopted feature inversion to reconstruct the converted speech. Experiments showed that the proposed method was very effective in converting whispered speech, with significant improvement in sound quality

Writing--original draft preparation, Q.Z. ; writing--review and editing, Z.W. ; software, Y.D. and J.Z. All authors have read and agreed to the published version of the manuscript. This research was funded by the National Natural Science Foundation of China (No. 61976198), the Key Research and Development Plan of Anhui Province (No. 201904d07020012), the Natural Science Research Key Project for Colleges and University of Anhui Province (No. KJ2019A0726), and the High-Level Scientific Research Foundation for the Introduction of Talent of Hefei Normal University (No. 2020 RCJ44). Not applicable. The authors declare no conflict of interest. ## References

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