EP0736995A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Improvements in or relating to speech recognition
Assignee: Texas Instruments Inc
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Filing: 1996-04-03
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Granted: —
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Expires: 2016-04-03
Abstract
Abstract The present invention provides for efficient echo cancellation in a voice-recognition system which includes barge-in capability. The system and method include a buffer controller (22) which stores the incoming signal received from a communications network during transmission of an outgoing signal which represents an outgoing prompt message to an interlaced buffer (21). A delay finder (27) then determines a channel delay associated with the communications network in accordance with the incoming signal and the outgoing signal. The delay finder (27) then stores a portion of the incoming signals, determined in accordance with the channel delay and filter length of an adaptive filter included in an echo canceler (24), into a delay buffer 23. The echo canceler 24, using the incoming signals stored in the delay buffer 23, then enhances the incoming signals in preparation for further processing.
Inventors
- 👤 Thomas Drew Fisher
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-31 14:00
CPC Classifications
H; H04; H04B; H04B3/00; H04B3/02; H04B3/20; H04B3/23; H04M; H04M3/00; H04M3/002; H04M3/42; H04M3/487; H04M3/493; G; G10; G10L; G10L15/00; G10L15/22; G10L21/00; G10L21/02; G10L21/0208; G10L2021/02082; H04M2201/00; H04M2201/40
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
197 words
A system for providing a voice-activated prompt interrupt across a communications channel comprising: a play task coupled to said communications channel for transmitting outgoing signals through a communications channel, said outgoing signals including an outgoing prompt message; a first buffer; a buffer controller coupled to said communications channel for receiving incoming signals from said communications channel and for storing said incoming signals and said outgoing signals from said play task to said first buffer, said incoming signals received during transmission of said outgoing signals including an echo of said outgoing prompt message; a second buffer; a delay finder coupled to said first buffer and said second buffer for determining a delay through said communications channel in accordance with said incoming signals and said outgoing signals stored in said first buffer and for storing a portion of said incoming signals to said second buffer in accordance with said delay and said predetermined tap filter length; and an echo canceler including an adaptive filter ahaving a predetermined tap filter length, said echo canceler being coupled to said second buffer and responsive to said portion of said incoming signal for removing said echo from said portion of said incoming signals.
Claim 2
Dependent Claim
94 words
The system according to Claim 1 further comprising: a call manager coupled to said communications channel for detecting incoming calls from the communications channel; an application interface coupled to said call manager and responsive to said incoming calls for generating an outgoing prompt message; the play task, being coupled to said application interface and responsive to said outgoing prompt message; the buffer controller, being coupled to said communications channel, to said first buffer and to said play task. the delay finder being operable to determine a channel delay in response to said incoming signals.
Claim 3
Dependent Claim
198 words
The system according to Claim 1 or Claim 2 further comprising: the buffer controller storing said outgoing signals to said first buffer and receiving incoming signals from said communications channel during said transmittion of said outgoing signals and storing said incoming signals to a second buffer; the delay finder, determining a first buffer offset signal in response to determining whether energy of said outgoing signals exceeds a first predetermined threshold; said delay finder further operable to determine a second buffer offset signal in response to correlating said outgoing signals in said first buffer with said incoming signals in said second buffer in accordance with said first buffer offset signal; said delay finder further operable to determine a channel delay in response to said first buffer offset and said second buffer offset; a third buffer; the echo canceler being coupled to said second buffer and to said third buffer for removing said echo from a portion of said incoming signals to provide enhanced incoming signals and for storing said enhanced incoming signals to said third buffer, said portion of said incoming signals determined by said delay finder in accordance with said channel delay and said predetermined tap filter length.
Claim 4
Dependent Claim
211 words
The system of Claim 3 further including: a fourth buffer; a linear predictive code generator, coupled to said echo canceler and to said fourth buffer, for generating linear predictive code vectors and determining associated energy levels in response to said enhanced incoming signals and for storing said linear predictive code vectors and said associated energy levels to said fourth buffer; an utterance extractor, coupled to said fourth buffer, for making a determination, in response to said associated energy levels, whether spoken words are included in said enhanced incoming signals and for initiating termination of said transmission of said outgoing prompt message and disabling said echo canceler in response to said determination; a fifth buffer; a speech generator coupled to said fourth buffer and to said fifth buffer and responsive to said determination made by said utterance extractor for generating speech parameters and speech features from said linear predictive code vectors and for storing said speech parameters and said speech features to said fifth buffer; and a speech recognition processor coupled to said utterance extractor, to said speech generator and to said fifth buffer for processing said speech parameters and said speech features to determine a response to said outgoing prompt message and for transmitting said response to said application program interface.
Claim 5
Dependent Claim
39 words
The system of Claim 4 wherein said speech recognition processor compares said speech parameters and said speech features to grammar downloaded from said call manager through said application program interface to determine said response to said outgoing prompt message.
Claim 6
Dependent Claim
43 words
The system of Claim 4 or Claim 5 wherein said speech recognition processor compares said speech parameters and said speech features to speech models downloaded from said call manager through said application program interface to determine said response to said outgoing prompt message.
Claim 7
Independent Claim
32 words
The system of any of Claims 4 to 6 wherein said linear predictive code generator determines said associated energy levels by determining the amplitudes of the resonances of said enhanced incoming signals.
Claim 8
Independent Claim
30 words
The system of any of Claims 4 to 6 wherein said linear predictive code generator determines said associated energy levels by determining the frequency spectrum of said enhanced incoming signals.
Claim 9
Independent Claim
126 words
A method for providing adjustable echo cancellation, comprising: transmitting outgoing signals representing an outgoing prompt message through a communications channel; receiving incoming signals from said communications channel during said transmission of said outgoing signals through said communications channel, said incoming signal including an echo of said outgoing prompt message; storing said incoming signals to a first buffer in response to receipt of incoming signals from a communications channel; determining a delay through said communications channel in response to said incoming signals and said outgoing signals using a delay finder; removing said echo from a portion of said incoming signals using an echo canceler, said portion determined in response to said delay and a predetermined tap filter length of an adaptive filter included in said echo canceler.
Claim 10
Dependent Claim
211 words
The method according to Claim 9 further comprising: transmitting an outgoing prompt message in response to receipt of an incoming call; storing outgoing prompt message signals representing said outgoing prompt message to a first buffer; storing said incoming signals to a second buffer, said incoming signals including an echo of said outgoing prompt message; determining a first buffer offset in response to determining whether energy of said outgoing prompt message signals exceeds a first predetermined threshold; correlating said outgoing prompt signals in said first buffer with said incoming signals in said second buffer in accordance with said first buffer offset; determining a second buffer offset signal in response to said correlating step; determining an incoming signal delay in response to said second buffer offset signal; and said step of removing said echo including generating enhanced incoming signals; storing said enhanced incoming signals to a third buffer; determining whether said enhanced incoming signals in said third buffer include speech to extract an utterance portion from said enhanced incoming signals; determining generalized speech parameters and generalized speech features of said utterance portion of said enhanced incoming signals; comparing said generalized speech parameters and said generalized speech features to stored speech models; and executing a speech application task in response to said comparing step.
References Cited (Backward Citations)
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