Invalidity dossier
US 6061651
Apparatus that detects voice energy during prompting by a voice recognition system
Current assignee: SpeechWorks International Inc
Added 9/23/2026, 1:48:26 PM
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Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview — US 6,061,651
Title: "Apparatus that detects voice energy during prompting by a voice recognition system"
Assignee: Original assignee SpeechWorks International Inc.; current assignee listed as SpeechWorks International Inc. (listing not a legal conclusion).
Key dates: Prior art date 1996-05-21; application US09/041,420 filed 1998-03-12; granted/publication date 2000-05-09; status "Expired – Lifetime," with anticipated expiration 2016-05-21.
Inventor: John N. Nguyen.
Purpose: The invention generally relates to speaker barge-in in voice recognition systems, and more specifically to detecting the onset of user speech on a telephone line that also carries voice prompts. Telephonic voice recognition systems play prompts the user often wishes to interrupt ("barge in"). Because the outgoing signal is fed back to the incoming line as an "echo," the recognizer hears its own prompt along with user speech; the prompt residue masks the desired speech, has wide dynamic range, and forces a higher detection threshold, degrading recognition.
Plain-language scope: The system predicts or models the prompt residue's time-varying energy and subtracts it from the line input signal. It forms an attenuation parameter relating prompt residue to the prompt itself (preferably the average energy difference between prompt and residue), then subtracts that parameter from the prompt energy to yield a predicted prompt residue, which is subtracted from the line input energy. If the result exceeds a detection margin, a user response is deemed present and a prompt-termination signal may be generated. In one embodiment, signals are sampled at 8000 samples/second in 120-sample frames (roughly 1/60 second), smoothed with a Hamming window, with the attenuation parameter continuously measured and updated as a moving average. The margin plus prompt replica constitutes a dynamic threshold, allowing a smaller fixed margin and earlier speech detection than fixed-threshold systems.
Source: https://patents.google.com/patent/US6061651/en
What the excerpt does not establish: It does not provide the full claim text, complete specification, drawing details beyond figure captions, prosecution history, validity, or any prior-art analysis. Reassignment entries shown in the source are not discussed here per scope limits.
Generated 10/1/2026, 9:52:49 PM
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Assignment history
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Prior art
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