Two-way voice communication methods and apparatus

• US 5,297,198 A
• Filed: 12/27/1991
• Issued: 03/22/1994
• Est. Priority Date: 12/27/1991
• Status: Expired due to Term

• Current Assignee: American Telephone & Telegraph Company (AT&T, Inc.)
• Original Assignee: AT&T, Inc.
• Inventors: Centurrino, Joseph R., Butani, Chandru T., Scheidemann, James F.
• Primary Examiner(s): Dwyer, James L.
• Assistant Examiner(s): FOURNIER, PAUL
• Application Number:
  US07/815,313
• Time in Patent Office: 816 Days
• Field of Search: 379/389, 379/390, 379/402, 379/404, 379/405, 379/419, 379/420, 381/57, 381/61
• US Class Current: 379/388.04
• CPC Class Codes: H04M 9/085 using digital techniques H04M9/082 takes precedence

Abstract

A speakerphone system has a speaker and microphone in a common acoustic environment and electrically preceded and succeeded, respectively, by receive and transmit sections and adapted, respectively, to reproduce as sounds by such speaker signals passed through such receive section from a remote station, and to convert sounds sensed by such microphone into signals passed through such transmit section to such station. A computer derives from the signals from the microphone an electric quantity which is a measure of the average audible ambient noise level in such environment, and the computer uses such quantity as one factor among others in switching signal losses between such two sections so as to change the state of operation of the system between transmit and receive states. As an improvement, there is derived from such quantity a control signal which effects dynamic adjustment of the gain in the receive section so that the average level of the sounds reproduced by the speaker will increase as such noise level increases, and conversely (Automatic Level Control). Other improvements are to provide for the system(a) a plurality of individually selectable interface circuits for matching the system to differently designed two-way voice communication channels in the outside world, (b) an auxiliary microphone for picking up voice sounds in the environment to be reproduced by the speaker, (c) an additional speaker not subject to automatic level control, and (d) sound tones produced under manual control in the environment by the system either to aid an installer in adjusting the system or to provide a reminder that the system is "on."

Claims

1. The improvement in two-way voice telecommunications apparatus comprising a hands-free speaker and a first hands-free microphone disposed at a local site in a common acoustic environment, housing means, signal processing means in said housing means and comprising receive and transmit sections electrically preceding and succeeding, respectively, said speaker and said microphone, said receive section having an input and being adapted to process and then supply to said speaker electrical signals received at said input and originated at a remote station outside said environment and representative of voice sounds at said station ("receive signals"), and said transmit section having an output and being adapted to process and then supply to said output, for transmission to said station, electrical signals originated at said microphone and representative of voice sounds in said environment ("transmit signals"), first and second loss stages in, respectively, said receive section and said transmit section and responsive to computer control to produce in said receive and transmit signals respective signal losses of selected variable value called for by such control, and a computer coupled to said two stages and responsive to, among other factors, information from said microphone to dynamically adjust the losses respectively produced thereby so as to switch the state of operation of said apparatus between at least transmit and receive states, and said improvement being that said acoustic environment served by said speaker is large, said speaker is a loudspeaker adapted to project into said environment paging announcements and other voice sounds audible in said environment at multiple locations separated from each other by more than the normal hearing distance for the normal spoken human voice, and said improvement also comprising a second auxiliary hands-free microphone disposed in said environment for converting voice sounds therein sensed by said electrical auxiliary microphone into electrical auxiliary voice signals, switch means for selectively effecting a connection of said electrical auxiliary voice signals to said receive section for passage therethrough to said loudspeaker, and means responsive to receive signals incoming to said receive section to disable such connection such that said electrical auxiliary voice signals do not reach said loudspeaker and only said receive signals pass through such section to said loudspeaker.

2. The improvement according to claim 1 in which said computer is responsive to, among other functions, information from said receive section to dynamically adjust the loss respectively produced by said two loss stages, and in which said improvement further comprises means operable when said auxiliary microphone is connected to said receive section to render said computer non-responsive to such information when it is derived from auxiliary voice signals transferred through such receive section.

3. The improvement in two-way voice telecommunications apparatus comprising a first hands-free speaker and a hands-free microphone each disposed at a first local site in a common acoustic environment, housing means, signal processing means in said housing means and comprising receive and transmit sections electrically preceding and succeeding, respectively, said speaker and said microphone, said receive section having an input and being adapted to process and then supply to said speaker electrical signals received at said input and originated at a remote station outside environment and representative of voice sounds at said station ("receive signals"), and said transmit section having an output and being adapted to process and then supply to said output, for transmission to said station, electrical signals originated at said microphone and representative of voice sounds in said environment ("transmit signals"), first and second loss stages in, respectively, said receive section and said transmit section and responsive to computer control to produce in said receive and transmit signals respective signal losses of selected variable value called for by such control, and a computer coupled to said two stages to dynamically adjust the losses respectively produced thereby so as to switch the state of operation of said apparatus between at least transmit state and receive states, and said improvement comprising a second hands-free auxiliary speaker disposed at a second local site acoustically isolated from said acoustic environment which includes said first local site, and switch means for selectively effecting a connection of said auxiliary speaker to said receive section between the input of said receive section and said loss stage therein such that said auxiliary speaker is supplied with receive signals incoming to said receive section without such signals passing through such loss stage to thereby be exposed to the signal losses produced by such stage.

4. The improvement in two-way voice telecommunications apparatus comprising a hands-free speaker and a hands-free microphone disposed at a local site in a common acoustic environment, an amplifier with manually settable gain preceding such speaker, housing means, signal processing means in said housing means and comprising receive and transmit sections electrically preceding and succeeding, respectively, said amplifier and said microphone, said receive section having an input and being adapted to process and then supply to said amplifier and speaker electrical signals received at said input and originated at a remote station outside said environment and representative of voice sounds at said station ("receive signals"), and said transmit section having an output and being adapted to process and then supply to said output, for transmission to said station, electrical signals originated at said microphone and representative of voice sounds in said environment ("transmit signals"), first and second programmable attenuators in, respectively, said receive section and said transmit section and responsive to computer control to be adjusted to respective loss settings therefor so as to produce in said receive and transmit signals respective signal losses of selected variable value called for by such control, a computer coupled to said two programmable attenuators and responsive to, among other factors, information from said microphone to derive from said information two separate indications which are direct measures of, respectively, the average level of ambient noise in said environment, and the average level in said environment of voice sounds present from time to time in said environment, and to dynamically adjust the respective loss settings of said two programmable attenuators so as to switch the state of operation of said apparatus between at least transmit and receive states, and said improvement being that said computer is responsive to said first indication while being substantially unresponsive to said second indication to be further operable on only said first programmable attenuator in said receive section to reset that attenuator to dynamically adjust the signal loss produced by such programmable attenuator in receive signals as a function of such noise level so as to cause voice sounds reproduced by said speaker from such signals to, over a range, increase in average level when such noise level increases and decrease in average level when such noise level decreases.

5. The improvement in the method comprising, providing at a local site a hands-free speaker and microphone in a common acoustic environment for utilization of said speaker and microphone, respectively, to reproduce as sound in said environment electrical voice signals received from a remote station outside said environment ("receive signals") and supplied to said speaker, and to reproduce voice sounds of people at said site as electrical voice signals to be transmitted to said station ("transmit signals"), electrically processing said receive and transmit signals before being applied to said speaker and transmitted to said station, respectively, by passing them through an electrical receive section and an electrical transmit section, respectively, providing a computer, utilizing said computer to electrically control the processing of said receive and transmit signals in, respectively, said receive and transmit sections so as to dynamically adjust losses produced in such sections in such signals therein and so as to switch the state of operation of the systems comprising the aforementioned components between at least transmit and receive states, providing a tone signal generator, and automatically calibrating said system upon each energization thereof with electricity by inducing said computer to control said generator in response to said energization to produce a burst of signals representative of tones of different frequency, supplying said signal burst to said speaker to be reproduced thereby as a burst of sound tones projected into said environment, detecting by said microphone the return lines produced in sound environment by such sound tone burst, and supplying the electric signals produced at said microphone from said echos as inputs to said computer to cause said losses in said sections to be automatically adjusted through control by said computer so as to calibrate such system for the acoustic parameters of said environment, and said improvement comprising, initiating and continuing under manual control of a person a signal fed to the computer to induce it to control said tone generator to produce over a time interval determined by that person a succession of such signal bursts reproduced by said speaker as a corresponding succession of bursts of sound tones projected into said environment and usable by an installer of said system to adjust one or more operating parameters thereof.

6. The improvement in the method comprising, providing at a local site a hands-free speaker and microphone in a common acoustic environment for utilization of said speaker and microphone, respectively, to reproduce as sound in said environment electrical voice signals received from a remote station outside said environment ("receive signals") and supplied to said speaker, and to reproduce voice sounds of people at said site as electrical voice signals to be transmitted to said station ("transmit signals"), electrically processing said receive and transmit signals before being applied to said speaker and transmitted to said station, respectively, by passing them through an electrical receive section and an electrical transmit section, respectively, providing a computer, utilizing said computer to electrically control the processing of said receive and transmit signals in, respectively, said receive and transmit sections so as to dynamically adjust losses produced in such sections in such signals therein and so as to switch the state of operation of the systems comprising the aforementioned components between at least transmit and receive states, providing a tone signal generator, and automatically calibrating said system upon each energization thereof with electricity by inducing said computer to control said generator in response to said energization to produce a burst of signals representative of tones of different frequency, supplying said signal burst to said speaker to be reproduced thereby as a burst of sound tones projected into said environment, detecting by said microphone the return lines produced in sound environment by such sound tone burst, and supplying the electric signals produced at said microphone from said echos as inputs to said computer to cause said losses in said sections to be automatically adjusted through control by said computer so as to calibrate such system for the acoustic parameters of said environment, and said improvement comprising, initiating and continuing under manual control of a person a signal fed to the computer to induce it to control said tone generator to produce a single frequency tone occurring intermittently in successive bursts of such tone and adapted to remind listeners that such system is in active operation.

7. The method comprising, providing at a local site a hands-free speaker and hands-free microphone in a common acoustic environment for utilization of said speaker and microphone, respectively, to reproduce as sounds in said environment electrical voice signals received from a remote station outside said environment ("receive signals") and supplied to said speaker, and to reproduce voice sounds of people at said site as electrical voice signals to be transmitted to said station ("transmit signals"), electrically processing said receive signals before they are applied to said speaker by passing them through an electrical receive section, developing via said microphone from audio acoustic energy in said environment an electrical composite signal comprising first and second components representative of, respectively, ambient noise in said environment and voice sounds present from time to time in said environment electrically analyzing said composite signal to provide a differential electrical response to said components which discriminates in favor of and against, respectively, such first and second components, and to derive from such response a control signal which is a relatively significant measure of the average level of said noise (the "transmit noise average"), and is relatively unaffected in value by the presence or absence of such voice sounds, and dynamically adjusting as a function of the value of said control signal the gain provided in said receive section for said receive signals so as, over a range, to increase and decrease the value of such gain when, respectively, said noise level increases and said noise level decreases, such dynamic adjusting of said gain superposing upon the gain of such receive section, as determined by other factors, a dynamic change in gain which is a function of a corresponding change in such average ambient noise level, such function being representable by a line graphed in vertical and horizontal coordinates having scales proportional to magnitude and representing such gain change and noise level change, respectively, and such line being in the form of a curve which is representative of constant intelligibility of said reproduced sounds with increasing ambient noise level, and the slope of which curve decreases with increase in noise level.