8 Speaker Recognition

The focus of this chapter is on facilities and network access-control applications of speaker recognition. Speech processing is a diverse field with many applications. Figure 8.1 shows a few of these areas and how speaker recognition relates to the rest of the field. This chapter will emphasize the speaker recognition applications shown in the boxes of Figure 8.1. Speaker recognition encompasses verification and identification. Automatic speaker verification (ASV) is the use of a machine to verify a person's claimed identity from his voice. The literature abounds with different terms for speaker verification, including voice verification, speaker authentication, voice authentication, talker authentication, and talker verification. In automatic speaker identification (ASI), there is no a priori identity claim, and the system decides who the person is, what group the person is a member of, or (in the open-set case) that the person is unknown. General overviews of speaker recognition have been given Abstract A tutorial on the design and development of automatic speaker recognition systems is presented. Automatic speaker recognition is the use of a machine to recognize a person from a spoken phrase. These systems can operate in two modes: to identify a particular person or to verify a person's claimed identity. Speech processing and the basic components of automatic speaker recognition systems are shown and design tradeoffs are discussed. The performances of various systems are compared. Figure 8.1 Speech processing. Speaker verification is defined as deciding if a speaker is who he claims to be. This is different than the speaker identification problem, which is deciding if a speaker is a specific person or is among a group of persons. In speaker verification, a person makes an identity claim (e.g., entering an employee number or presenting his smart card). In text-dependent recognition, the phrase is known to the system and it can be fixed or not fixed and prompted (visually or orally). The claimant speaks the phrase into a microphone. This signal is analyzed by a verification system that makes the binary decision to accept or reject the user's identity claim or possibly to report insufficient confidence and request additional input before making the decision. A typical ASV setup is shown in Figure 8.2. The claimant, who has previously enrolled in the system, presents an encrypted smart card containing his identification information. He then attempts to be authenticated by speaking a prompted phrase(s) into the microphone. There is generally a …