Perceived loudness of speech based on the characteristics of glottal excitation source.

The impulse-like characteristic of glottal excitation in speech production is an important factor in the perception of loudness of speech signals. This characteristic is attributed to the abruptness of the closing phase in the glottal cycle. In this paper, an acoustic feature, called strength of excitation, is proposed to represent the impulse-like nature of excitation. The strength of excitation is derived from the linear prediction residual of speech signals, where the residual can be considered as an estimate of the source of excitation. Since the loudness of speech is perceived over one or more utterances of speech, it is hypothesized that the distribution of strength of excitation is indicative of the perceived loudness of speech. The distribution of strength of excitation is shown to distinguish between soft and loud utterances of speakers. The distribution can also help in discriminating between the loudness of two speakers. The loudness measure obtained using the distribution of the strength of excitation is in agreement with the subjective judgment of loudness of speech.