Basic Speech Processing Concepts

Abstract

Before we explore the algorithms and techniques used to process speech signals to accomplish various objectives in an embedded application, we need to understand some fundamental principles behind the nature of speech signals. Of particular importance are the temporal and spectral characteristics of different types of vocal sounds produced by humans and what role the human speech production system itself plays in determining the properties of these sounds. This knowledge enables us to efficiently model the sounds generated, thereby providing the foundation of sophisticated techniques for compressing speech. Moreover, any spoken language is based on a combination and sequence of such sounds; hence understanding their salient features is useful for the design and implementation of effective speech recognition and synthesis techniques. In this section, we will learn how to classify the basic types of sounds generated by human voice and the underlying time-domain and frequency-domain characteristics behind these different types of sounds. Finally, and most importantly, we will explore some popular speech processing building-block techniques that enable us to extract critical pieces of information from the speech signal, such as which category a speech segment belongs to, the pitch of the sound, and the energy contained therein.