The effects of several transmission systems on an automatic speaker verification system

In an earlier report, the effects of several transmission systems on speaker verification by human listeners were investigated. It was shown that the transmission system played a significant role in the speaker verification process. In this paper, we show the effects of the transmission system on an existing automatic speaker verification system in which the measured features are pitch and gain as a function of time for a specified utterance. In this experiment, there were 10 male and 10 female customers and 40 male and 40 female impostors. Fifty utterances were recorded using a conventional telephone connection over a period of two months. All utterances were post-processed by an adpcm coding system and lpc vocoding system. When the reference and test utterances were subjected to different transmission systems, no significant difference in the verification accuracy of this automatic system was found. This result verifies that pitch and gain are robust features for use in a speaker verification system.