CA2129102A1 - Feedback Level Estimator Between Loudspeaker and Microphone - Google Patents

Feedback Level Estimator Between Loudspeaker and Microphone

Info

Publication number
CA2129102A1
CA2129102A1 CA 2129102 CA2129102A CA2129102A1 CA 2129102 A1 CA2129102 A1 CA 2129102A1 CA 2129102 CA2129102 CA 2129102 CA 2129102 A CA2129102 A CA 2129102A CA 2129102 A1 CA2129102 A1 CA 2129102A1
Authority
CA
Canada
Prior art keywords
microphone
signal
loudspeaker
echo
microphone signal
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
CA 2129102
Other languages
French (fr)
Other versions
CA2129102C (en
Inventor
Peter L. Chu
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Polycom Inc
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of CA2129102A1 publication Critical patent/CA2129102A1/en
Application granted granted Critical
Publication of CA2129102C publication Critical patent/CA2129102C/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R3/00—Circuits for transducers, loudspeakers or microphones
    • H04R3/02—Circuits for transducers, loudspeakers or microphones for preventing acoustic reaction, i.e. acoustic oscillatory feedback
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M9/00—Arrangements for interconnection not involving centralised switching
    • H04M9/08—Two-way loud-speaking telephone systems with means for conditioning the signal, e.g. for suppressing echoes for one or both directions of traffic
    • H04M9/082—Two-way loud-speaking telephone systems with means for conditioning the signal, e.g. for suppressing echoes for one or both directions of traffic using echo cancellers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2430/00—Signal processing covered by H04R, not provided for in its groups
    • H04R2430/03—Synergistic effects of band splitting and sub-band processing

Landscapes

  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Otolaryngology (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
  • Circuit For Audible Band Transducer (AREA)
  • Filters That Use Time-Delay Elements (AREA)
  • Telephone Function (AREA)

Abstract

An improved echo cancelling device (18) for reducing the effects of acoustic feedback between a loudspeaker and microphone in a communication system. The device includes an adjustable filter (50) for receiving a loudspeaker signal and generating in response thereto an echo estimation signal. The device subtracts (54) the echo estimation signal from the microphone signal to produce an echo corrected microphone signal. During periods of time when the microphone signal is substantially derived from acoustic feedback between the loudspeaker and the microphone, the device adjusts (58) transfer characteristics of the filter (52) to reduce the echo corrected microphone signal. The improvement includes estimating from the adjusted transfer characteristics an energy transfer ratio representative of the ratio of the energy of the microphone signal to the energy of the loudspeaker signal.
The device compares the microphone signal to the energy transfer ratio multiplied by the loudspeaker signal to identify periods of the time when the microphone signal is substantially derived from acoustic feedback between the loudspeaker and the microphone.
CA002129102A 1992-02-19 1993-01-08 Feedback level estimator between loudspeaker and microphone Expired - Lifetime CA2129102C (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US07/837,729 1992-02-19
US07/837,729 US5263019A (en) 1991-01-04 1992-02-19 Method and apparatus for estimating the level of acoustic feedback between a loudspeaker and microphone
PCT/US1993/000161 WO1993017510A1 (en) 1992-02-19 1993-01-08 Feedback level estimator between loudspeaker and microphone

Publications (2)

Publication Number Publication Date
CA2129102A1 true CA2129102A1 (en) 1993-09-02
CA2129102C CA2129102C (en) 1999-09-14

Family

ID=25275249

Family Applications (1)

Application Number Title Priority Date Filing Date
CA002129102A Expired - Lifetime CA2129102C (en) 1992-02-19 1993-01-08 Feedback level estimator between loudspeaker and microphone

Country Status (6)

Country Link
US (1) US5263019A (en)
EP (1) EP0627139B1 (en)
JP (1) JP3567242B2 (en)
CA (1) CA2129102C (en)
DE (1) DE69324002T2 (en)
WO (1) WO1993017510A1 (en)

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Also Published As

Publication number Publication date
DE69324002T2 (en) 1999-07-15
JPH07504075A (en) 1995-04-27
JP3567242B2 (en) 2004-09-22
EP0627139A1 (en) 1994-12-07
EP0627139A4 (en) 1995-08-30
DE69324002D1 (en) 1999-04-22
US5263019A (en) 1993-11-16
EP0627139B1 (en) 1999-03-17
WO1993017510A1 (en) 1993-09-02
CA2129102C (en) 1999-09-14

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