Claims
- 1. In a speech recognition system, the improvement comprising apparatus for detecting the presence of user speech on a telephone line input to the system concurrent with the emission of a voice prompt by said system, comprising:A. means (1) forming a first measurement of said input over at least a first interval characterized primarily by residue of said prompt, and (2) forming a measurement over at least a second interval characterized primarily by both said prompt residue and user speech; B. means forming an attenuation parameter based on said first and second measurements; C. means for comparing said input over intervals subsequent to said first and second intervals with said attenuation parameter and providing a prompt-termination signal when said input and said attenuation parameter bear a defined relation to each other; and D. means responsive to said prompt-termination signal to terminate said prompt.
- 2. Apparatus according to claim 1 in which said attenuation parameter is a function of the difference in amplitude between the prompt and the line signal in the absence of user speech.
- 3. Apparatus according to claim 1 in which said attenuation parameter is a function of the difference in energy between the prompt and the line signal in the absence of user speech.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a divisional of U.S. application Ser. No. 09/041,419 filed Mar. 12, 1998, now U.S. Pat. No. 6,266,398 issued Jul. 24, 2001 which is a divisional of U.S. application Ser. No. 08/651,889 filed May 21, 1996, now U.S. Pat. No. 5,765,130 issued Jun. 9, 1998.
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