When we speak of the form of words, we usually have in mind some representation of their sound. Our first topic in this chapter will therefore be a brief description of the nature and organization of the sounds of words. The second topic we shall address is the psycholinguistic question of how these sounds are produced. We shall review studies dealing with the stages involved in the planning and production of sounds of words. We shall then turn to studies of aphasic patients' abilities to produce the sounds of words correctly, and relate their difficulties in this function to the structure of the sound system and to the stages of production of the sounds of words.

The sounds that make up words are organized in quite specific ways. Some features of the organization of the sounds of words are universal to all human languages. Others reflect particular properties of individual languages. The way linguists approach the investigation of the structure of the sound system is to look for words that are minimally different in their sound patterns and then to build a theory of the sounds of a language on the basis of these differences. For instance, the words bat and pat differ in their first sound. The words blackboard and black board differ in their stress contours. The word pulley can be spoken so that the first syllable is /pull/ and the second syllable is /ey/, or so that the first syllable is /pul/ and the second syllable is /ley/. These three contrasts exemplify three different levels of organization of the sound system.