MAS.632 Conversational Computer Systems - MIT OpenCourseWare

VOCAL TRACT
Speech Production and Perception
A basic knowledge of the physiology of speech production and its perception is
necessary to understand both speech synthesis and speech recognition as well as
compression techniques. This chapter provides an overview of the production and
perception of speech. It briefly treats the organs of speech, i.e., the vocal tract and
the auditory system. An articulatory model of speech is presented; this explains
the different speech sounds of a language in terms of how they are produced.
Finally, it introduces some basic findings of psychoacoustics that relate to the
manner in which sound is perceived by the listener.
To distinguish the various types of sounds in English and the mechanisms
whereby they are produced some signal processing terms are introduced. In this
text, very simple and intuitive descriptions of such terms are given; more formal
definitions may be found in texts on signal processing.
The vocal tract is the set of organs that produce speech sounds; these organs are
also used for eating, drinking, and breathing. As seen in Figure 2.1, the vocal
tract includes portions ofthe throat, mouth, and nasal cavities. These organs, the
articulators, are moved to various configurations to produce the different
sounds that constitute speech. The primary topic of this section is the production
of speech sounds in general; the next section classifies the sounds specific to
English.