Improving the modeling of the noise part in the harmonic plus noise model of speech

Harmonic + noise model (HNM) is a hybrid model of speech with a harmonic component and a noise component. While the harmonic part describes efficiently the periodicities in speech signals (voiced parts), modeling of the noise part introduces artifacts primarily because of the specific time-domain characteristics of noise in voiced speech. In this paper, we concentrated on the modeling of noise in voiced frames. To model the temporal characteristics of noise, we study three time envelopes in the context of HNM; triangular envelope, Hilbert envelope and energy envelope. Listening tests showed a clear preference for the Energy envelope and Hilbert envelope for male voices and to a lesser extent the same conclusions can be drawn for female voices.