In Chapters 22–29, we introduced the basics of automatic speech-recognition systems. However, there are a number of related application areas that use many of the same tools and perspectives. One such class of applications is speaker recognition, for which speaker verification is a particularly important example. Here1 we describe some of the basic principles of this application.
Speech contains many characteristics that are specific to each individual, many of which are independent of the linguistic message for an utterance. In Chapter 29 we discussed some of these characteristics from the perspective of speech recognition, for which they generally are a source of degradation. For instance, each utterance from an individual is produced by the same vocal tract, tends to have a typical pitch range (particularly for each gender), and has a characteristic articulator movement that is associated with speaker, dialect, or gender. All of these factors have a strong effect on the speech that is highly correlated with the particular individual who is speaking. For this reason, listeners are often able to recognize the speaker identity fairly quickly, even over the telephone. Artificial systems recognizing speakers rather than speech have been the subject of much research over the past 30 years, and multiple commercial systems are currently ...