Introduction

Intonation, as we have defined it, is the ensemble of pitch variations in the course of an utterance. This perceptual impression of speech melody correlates, to a first approximation, with changes in the fundamental frequency (Fo) of the signal. These Fo variations, in turn, reflect changes in the rate at which the vocal cords vibrate. Therefore, if intonation is approached from a phonetic angle, its form of appearance can be described in perceptual, acoustic and physiological terms.

This chapter is devoted to such a threefold characterization of intonation. In section 2.1 we present some basic insights into the physiological mechanisms that control the rate of vocal-cord vibration. Section 2.2 is devoted to the acoustic manifestation of this vibration and to some of the ways in which it can be extracted from the speech signal. Section 2.3 offers a rather detailed account of the psychoacoustic literature concerning the perception of pitch in pure and complex tones and in speech-like signals. The information in sections 2.1 and 2.2 is intended to provide the necessary background knowledge for the reading of subsequent chapters. The expert reader can skip these sections. In section 2.3 comparable background information is given, but it is shown in addition that the psychoacoustically defined thresholds do not account for the selective sensitivity of the listener when extracting pitch information from the speech signal.

We will round off the entire chapter (2.4) with considerations about which strategy can best be chosen in an attempt to integrate the three main aspects as they have been presented in this chapter, viz. those of production, of acoustic manifestation and of perception of speech pitch.