US3814856A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Control apparatus for sound reinforcement systems
Assignee: Individual
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Filing: 1973-02-22
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Granted: 1974-06-04
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Expires: 1993-02-22
Abstract
Abstract A control apparatus for a sound reinforcement system having plural audio input program microphones installed in a theater or like environment. The ambient sound or noise level in the environment is sensed and is employed to control each microphone individually so that a microphone is activated only if the audio material impinging thereon exceeds the ambient noise level. The audio output of the entire system is continuously and automatically adjusted so that the gain or amplification to which audio program signals are subjected is proportional to the number of program microphones that are active, thereby optimizing the operation of the system.
Inventors
- 👤 D Dugan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 05:22
CPC Classifications
H; H04; H04R; H04R27/00
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
222 words
Sound reinforcement apparatus for a system that includes a plurality of program microphones and at least one loudspeaker and is adapted to operate in the presence of ambient noise, comprising in combination: means for generating a direct current noise reference signal having a level proportional to the ambient noise level; a plurality of audio signal processors, each of said processors being associated with a respective one of said program microphones, each said processor being adapted to transmit the output of the associated program microphone only when such output exceeds the ambient noise level and including means for generating a direct current program envelope signal having a level proportional to the level of the associated program microphone output; means for comparing said program envelope signal with the noise reference signal to develop a gating signal only when said program envelope signal exceeds the noise reference signal by a predetermined ratio; an audio signal controller responsive to said gating signal for transmitting the audio output of the associated program microphone only when said gating signal is present; and feedback means for providing hysteresis to maintain said gating signal so long as the audio output of the associated program microphone remains within a given increment of said predetermined ratio; and means for mixing outputs of all said processors and feeding them to said loud speaker.
Claim 2
Dependent Claim
222 words
Sound reinforcement apparatus for a system that includes a plurality of program microphones and at least one loudspeaker and is adapted to operate in the presence of ambient noise, comprising in combination: means for generating a direct current noise reference signal having a level proportional to the ambient noise level; a plurality of audio signal processors, each of said processors being associated with a respective one of said program microphones, each said processor being adapted to transmit the output of the associated program microphone only when such output exceeds the ambient noise level and including means for generating a direct current program envelope signal having a level proportional to the level of the associated program microphone output; means for comparing said program envelope signal with the noise reference signal to develop a gating signal only when said program envelope signal exceeds the noise reference signal by a predetermined ratio; an audio signal controller responsive to said gating signal for transmitting the audio output of the associated program microphone only when said gating signal is present; and feedback means for providing hysteresis to maintain said gating signal so long as the audio output of the associated program microphone remains within a given increment of said predetermined ratio; and means for mixing outputs of all said processors and feeding them to said loud speaker.
Claim 3
Dependent Claim
69 words
Apparatus according to claim 1 wherein said output mixing means includes a summing network having an individual input associated with and connected to each respective audio signal controller, said network having a single output, a variable gain amplifier having an input connected to said single output, and means for varying the gain of said variable gain amplifier in proportion to the number of audio signal controllers that are transmitting.
Claim 4
Dependent Claim
97 words
Apparatus according to claim 2 wherein said gain varying means includes means for adding the DC output signals from all said comparing means in said processors to derive a DC voltage having a magnitude proportional to the number of said signal controllers that are transmitting, and means connecting said adding means to said variable gain amplifier so that said variable gain amplifier has a gain directly proportional to the quantity Square Root n/N in which n represents the total number of program microphones in the system and N represents the number of program microphones that are transmitting.
Claim 5
Dependent Claim
79 words
Apparatus according to claim 1 wherein said noise reference signal generating means comprises a noise microphone disposed in the same environment as said program microphones and said loudspeaker, means for rectifying the output of said noise microphone, and filter means connected to said rectifying means for generating a DC signal that varies as the envelope of the ambient noise impinging on said noise microphone, said rectifying means being connected to said comparing means in all said audio signal processors.
Claim 6
Dependent Claim
56 words
Apparatus according to claim 4 in combination with a logarithmic amplifier connected in circuit between said noise microphone and said rectifying means, said logarithmic amplifier being adapted to amplify low level noise signals by an amount greater than high level noise signals so as to compress the voltage range over which the ambient noise signal varies.
Claim 7
Dependent Claim
106 words
Apparatus according to claim 1 wherein said direct current program envelope generating means in each said audio signal processor comprises a logarithmic amplifier connected to the output of each said program microphone, said logarithmic amplifier being adapted to amplify low level program signals by an amount greater than high level program signals so as to compress the voltage range over which the audio signal varies, means for rectifying the output of said logarithmic amplifier, and filter means connected to said rectifying means for generating a DC signal that varies as the envelope of the audio program signal, said rectifying means being connected to said comparing means.
Claim 8
Dependent Claim
43 words
Apparatus according to claim 1 in combination with means connected to said comparing means for affording a visual indication when said gating signal is developed and means for selectively adjusting the predetermined ratio between said program envelope signal and said noise reference signal.
Claim 9
Dependent Claim
26 words
Apparatus according to claim 7 wherein said adjusting means includes a variable attenuator in circuit between said noise reference signal generating means and said comparing means.
Claim 10
Dependent Claim
137 words
Output control apparatus for an audio reinforcement system that has a plurality of audio program inputs and a single output, said control apparatus comprising a variable gain amplifier having an output terminal connected to said single output, an input terminal, and a control terminal, said variable gain amplifier being adapted to boost a signal applied at said input terminal by an amount proportional to the magnitude of a control signal applied to said control terminal, means for summing all said audio program inputs into said input terminal, and means connected to said control terminal for producing said control signal that automatically and continuously varies in proportion to the number of audio program inputs that are active so that the gain of said variable gain amplifier bears an inverse relation to the number of active audio program inputs.
Claim 11
Dependent Claim
137 words
Output control apparatus for an audio reinforcement system that has a plurality of audio program inputs and a single output, said control apparatus comprising a variable gain amplifier having an output terminal connected to said single output, an input terminal, and a control terminal, said variable gain amplifier being adapted to boost a signal applied at said input terminal by an amount proportional to the magnitude of a control signal applied to said control terminal, means for summing all said audio program inputs into said input terminal, and means connected to said control terminal for producing said control signal that automatically and continuously varies in proportion to the number of audio program inputs that are active so that the gain of said variable gain amplifier bears an inverse relation to the number of active audio program inputs.
Claim 12
Dependent Claim
156 words
Apparatus according to claim 9 in combination with means for generating a DC noise reference signal having a level proportional to the noise level in the audio program environment, means associated with each of said audio program inputs for generating a DC program envelope signal having a level proportional to the level of said audio program input, a plurality of comparators one of which is associated with each said audio program input and is adapted to produce a gating signal when the level of the program envelope signal exceeds the noise reference signal by a predetermined ratio, a network for adding all said gating signals, and means connecting said adding means to said variable gain amplifier so that said variable gain amplifier has a gain directly proportional to the quantity Square Root n/N in which n rePresents the total number of audio program inputs in the system and N represents the number of gating signals present.
References Cited (Backward Citations)
US3588360A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-03 | 1977-12-03 | 1978-06-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-03 | 1981-12-03 | 1982-06-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-03 | 1985-12-03 | 1986-06-04 | $7700.00 | Window Closed / Lapsed |