1. Field of the Invention
This invention relates generally to systems for telephonic communications with audio message storage and retrieval and, more particularly, to telephonic communications involving repertory or abbreviated call signal generation and abbreviated dialing. The invention further relates to systems based on artificial intelligence techniques, particularly those using knowledge processing, and especially to adaptive or trainable systems that create sets of rules and use parallel distributed processing components.
2. Description of the Related Art
Both rotary and touch-tone dialing rely on telephone numbers to initiate desired telephone connections. Telephone companies use the numbers to route calls, but people now depend on the numbers for all telephone communications. This is somewhat unnatural because people generally select those with whom they would like to talk by name or other convention. Indeed, telephone directories are arranged by name, not number.
Some companies started to develop voice-activated dialing systems to replace touch-tone dialing. In such systems, telephone users speak the name of an individual or destination into the microphone of a telephone handset to initiate a telephone call. Voice-dialing thus allows connection to be made directly, avoiding the step of looking up names to locate corresponding telephone numbers.
Examples of experimental voice-dialing systems appear in L. R. Rabiner, J. G. Wilpon, and A. E. Rosenberg, "A voice-controlled, repertory-dialer system," Bell System Technical Journal, Vol. 59, No. 7 (September, 1980), and U.S. Pat. No. 4,348,550 to Pirz et al. These systems have limited accuracy and speed and cost a great deal of money.
Recent advances in speech recognition have improved performance dramaticaly, particularly for systems that are not trained to a particular speaker that have, until recently, performed worse than systems trained to particular speakers. In addition, the increasing computational and memory capacity and decreasing cost of computing hardware improve the commercial viability for simpler applications of speech recognition such as voice-dialing.
Limitations on the performance of voice-dialing systems, however, still significantly reduce their commercial applicability. Such systems frequently make errors, with the rate of errors increasing with increased vocabulary size and factors such as environmental noise, unusual accents, and the use of foreign or unusual names that are difficult to pronounce consistently. The limited accuracy of recognition performance resulting from these factors restricts the possible range of applications for conventional voice-dialing systems by limiting the vocabulary, environment, user population, and hardware platforms on which the systems can run.
It is therefore desirable to seek techniques that will improve the accuracy and speed of speech recognition performance in voice-dialing systems. A number of alternative techniques have been used in the past. One approach is to ask the user for verification before dialing ("Did you say Anatoly Korsakov?"), and presenting a different name if the user says "No." See, for example, U.S. Pat. No. 5,222,121 to Shimada. Another approach, disclosed by Iida et al. (U.S. Pat. No. 4,864,622), modifies or replaces the voice template used for speech recognition when the template is not performing adequately.
None of these approaches, however, really improves speech recognition performance for voice-dialing systems. They merely require additional user interaction to assist in the voice-dialing process.