A Study on the Ability to Automatically Recognize Telephone-Quality Speech From Large Customer Populations

Abstract

To ascertain whether a speaker-independent word recognition system, using current technology, could function in normal telephone environments, it was necessary to conduct a study under such real-world conditions. Such an experiment was described by Wilpon and Rabiner (1983), in which telephone customers, speaking under ordinary telephone conditions, in Portland, Maine, were asked to speak their telephone number as a sequence of isolated digits. For each customer a maximum of four digits were obtained. The results from that study were very encouraging and led to further improvements in our recognition systems. To further study the feasibility of implementing speech recognition systems for general use over the telephone network, another field study was initiated. In this test, spoken seven-digit telephone numbers were obtained from a large number of telephone customers over a variety of transmission facilities in Baton Rouge, Louisiana. This paper presents the results of several recognition experiments performed on this database. Experiments were also carried out quantifying the robustness of template sets created in Portland, Baton Rouge, and under laboratory conditions in our Murray Hill, New Jersey, laboratory. Finally, a recognition system that incorporates syntactic information available in a seven-digit telephone is discussed. Our tests indicate a number of distinct real-world problems that must be considered when implementing a speech recognition system for widespread use. A discussion of the overall results and the implications for future research will be given.