Phonetic Category Structure and Its Influence on Lexical Processing

It is generally assumed that the phonetic categories of speech are not indissoluble wholes, but rather can be characterized in terms of a bundle of phonetic or distinctive features. These features may be defined in terms of either acoustic or articulatory attributes of the speech signal. However, it is also the case that at least from an acoustic or perceptual point of view, each of these phonetic features is also defined by a set of acoustic properties. For example, as shown in Figure 1, the phonetic category corresponding to [d] is defined in terms of a set of features and each feature in turn is signaled by a number of acoustic properties. Thus, the phonetic feature [voice], distinguishing voiced and voiceless stop consonants in English, is characterized by a number of attributes including glottal excitation, fundamental frequency, burst amplitude, and vowel length.