Measuring Speech. Fundamental frequency and pitch.

International audienceIn this chapter, we introduce the reader to the concepts of pitch and fundamental frequency from a functional, physiological and physical perspective. Several issues, including the modelling of intonation, pitch detection and measurement and acoustic scales, described below, are addressed to inform the reader about best practice for teaching and learning.Pitch, corresponding to the subjective impression of whether individual speech sounds are perceived as relatively high or low, as on a musical scale, is an important characteristic of spoken language, contributing in some languages to the lexical identity of words (tone and accent) and in all languages to the perception of the intonation pattern of utterances. Pitch corresponds to the physiological parameter of the frequency of vibration of the vocal folds (aka vocal cords) which can be measured in cycles per second (cps), or the equivalent acoustic parameter of fundamental frequency (f0), measured in hertz (Hz).Estimating and measuring fundamental frequency and modelling pitch is not an easy task. In this chapter, we first present some automatic models of pitch that have been developed both for speech synthesis and for the empirical study of intonation patterns. We then address issues related to the detection and measurement of fundamental frequency, including tracking/detection errors and explain how many of these errors can in fact be avoided by an appropriate choice of pitch ceiling and floor settings. We finally discuss the use of acoustic scales (e.g. linear, logarithmic, psychoacoustic) in the literature for the measurement of pitch. Based on evidence from recent findings in neuronatomy, neurophysiology, behavioural studies and speech production, we suggest that a new scale, the Octave-Median (OMe) scale, appears to be more natural for the study of speech prosody