Telephonic communications – Terminal – Having muting
Reexamination Certificate
1998-06-30
2001-04-03
Dorvil, Richemond (Department: 2741)
Telephonic communications
Terminal
Having muting
C379S351000
Reexamination Certificate
active
06212275
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention generally relates to a telephone and, more particularly, to long line telephonic noise reduction and to automatic muting apparatus and methods of muting.
A common problem with telephonic communication particularly during conference telephonic calls between multiple locations involving varied communication links, such as radio, communication satellite, under sea cable and local loops, is the generation of audible whistle type noise. This noise is generated most often when there are speaking pauses of the participants of the conference telephone call.
The present inventors have determined that this noise is caused at least in part by acoustical feedback from the telephone speaker to the telephone microphone. This feedback noise problem is particularly acute in the case of so-called speaker telephones, including those built in to desk top computers, video telephones and the like. This is believed by the inventors to be due to several factors. These factors includes the fact that the audio input to the speaker telephone must be of sufficient magnitude to drive a loud speaker that can be heard any where in a room. Also, microphones that are used in speaker telephones have sufficient sensitivity to enable good pickup of sounds anywhere within a room in which the speaker telephone is located while the microphone is acoustically less isolated than in the case of a telephone employing a handset.
Some speaker telephones operate on a simplex basis and automatically mute the speaker telephone microphone during such time speech or other sound above a preselected threshold magnitude is being substantially continuously received and converted to audible sound by the telephonic speaker. During this speaking time, the output signals from the speaker telephone microphone is switched out of circuit, and connection of microphonic output signals to the telephone line is prevented and the communication line is said to be “captured” by the incoming caller. The communication link then remains captured until there is a pause in speaking. Then, when there is a pause, the muting of the microphone is terminated, or unmuted. The microphone is said top be open or on. During the speaking pauses, any party to the conference is enabled to capture the one-way (at a time) communication link. When the local caller starts speaking when the microphone is on the local caller captures the line. Speaking of the local caller, in the case of the other speaker telephones also being simplex, will cause the microphones of the other speaker telephones to be muted until there are pauses in the speaking of the local caller.
Other speaker telephones operate on a duplex basis via a hybrid interface which enables simultaneous two-way conversation. In such duplex speaker telephones, there is no automatic muting of the microphone during speaking of the remote caller and the microphone remains on at all times unless manually turned of by the local caller.
SUMMARY OF THE INVENTION
In accordance with the present invention, the noise problems associated with telephones due to acoustical feedback noted above are overcome by automatically muting the microphone whenever the local caller, or user, pauses in speaking.
Preferably, in accordance with the invention a telephone having a microphone and an audio speaker is provided with an automatic muting circuit means for detecting pauses in speaking of a local user and means responsive to the detecting means for automatically muting the microphone. A signal comparator compares signals from the microphone and the audio speaker and is connected to the automatic muting circuit to actuate the automatic muting circuit if the signals from the microphone and the audio speaker have substantially the same waveform. The signal comparator is preferably a speech subtractor that subtracts one of the signals from the microphone and the speaker from another of the signals from the microphone and the speaker, and the detecting means includes a pair of amplifiers with automatic gain control to respectively amplify the signals from the microphone and the audio speaker to substantially the same level prior to subtraction by the speech subtractor. The microphone is automatically opened for transmission of microphonic output signals whenever a local user speaks into the microphone.
Thus, in accordance with the method of the invention the microphone is automatically muted by the steps of detecting pauses in speaking of a local user and then responding to the detection of the speaking pauses by automatically muting the microphone.
REFERENCES:
patent: 2878314 (1959-03-01), Laurence
patent: 3562791 (1971-02-01), Baker
patent: 3839604 (1974-10-01), Pardee
patent: 3928733 (1975-12-01), Hueber
patent: 3939311 (1976-02-01), Smith
patent: 4472601 (1984-09-01), Wilson
patent: 4536616 (1985-08-01), Kaire
patent: 4700383 (1987-10-01), Takagi et al.
patent: 4703507 (1987-10-01), Holden
patent: 4847897 (1989-07-01), Means
patent: 5384842 (1995-01-01), Tapping et al.
patent: 5533133 (1996-07-01), Lamkin et al.
patent: 5604145 (1997-02-01), Hannah et al.
patent: 5751822 (1998-05-01), Yamaguchi et al.
patent: 5784457 (1998-07-01), Haba
patent: 5982880 (1999-11-01), Kim
Dorvil Richemond
Lucent Technologies - Inc.
Patti Carmen B.
Wildman Harrold Allen & Dixon
LandOfFree
Telephone with automatic pause responsive, noise reduction... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Telephone with automatic pause responsive, noise reduction..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Telephone with automatic pause responsive, noise reduction... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2470184