US3732370A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Equalizer utilizing a comb of spectral frequencies as the test signal
Assignee: United Recording Electronic Industries
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Filing: 1971-02-24
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Granted: 1973-05-08
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Expires: 1991-02-24
Abstract
Abstract A system and method is described for electronically equalizing the composite transfer function of a loud speaker system and room which receives the sound generated by the speaker system. A test signal source is broadcast into a room through the normal loud speaker amplifier system. A substantially flat microphone and preamplifier is used to detect the system and feed the detected audio signal through a bank of audio filters substantially covering the low, middle, and high range audio spectrum from approximately 30 cycles to 20 kilohertz (KHZ) by using approximately three narrow band peaking filters per octave. The power in the bandwidth of each filter is detected and measured against a known reference and the individual gain of each of the filters is adjusted to obtain a substantially flat acoustic response. The normal conventional input sound source, be it a tuner or tape deck, is then fed through the adjusted bank of narrow band filters directly into the audio sound system for broadcast into the room in the conventional manner.
Inventors
- 👤 J Sacks
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 19:56
CPC Classifications
H; H04; H04S; H04S1/00; H04S1/007; H03; H03G; H03G5/00; H03G5/02; H03G5/025; H04S7/00; H04S7/30
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
123 words
A system for equalizing an audio sound transducer system with an environment adapted to receive the sound generated by said sound system comprising, means for generating a signal source comprising a comb of spectral frequencies in the audio range, means for feeding said comb of frequencies into the audio sound transducer system for broadcast into the environment, a plurality of contiguous narrow band filters substantially covering the band of said comb of spectral frequencies, means for detecting and feeding said comb of sPectral frequencies through said plurality of narnow band filters, means for measuring the spectral power in the bandwidth of at least one of said filters, and means for comparing and controlling the power output of the filter against a known reference.
Claim 2
Independent Claim
123 words
A system for equalizing an audio sound transducer system with an environment adapted to receive the sound generated by said sound system comprising, means for generating a signal source comprising a comb of spectral frequencies in the audio range, means for feeding said comb of frequencies into the audio sound transducer system for broadcast into the environment, a plurality of contiguous narrow band filters substantially covering the band of said comb of spectral frequencies, means for detecting and feeding said comb of sPectral frequencies through said plurality of narnow band filters, means for measuring the spectral power in the bandwidth of at least one of said filters, and means for comparing and controlling the power output of the filter against a known reference.
Claim 3
Dependent Claim
30 words
A system according to claim 1 in which said signal source is a square wave and said comb of frequencies are representative of the odd harmonics comprising said square wave.
Claim 4
Dependent Claim
31 words
A system according to claim 1 in which said narrow band filters are all peaking filters each having a separate gain control for individually controlling the gain of each peaking filter.
Claim 5
Dependent Claim
26 words
A system according to claim 3 in whith said filters each comprise a bridge T null network in a feedback loop for giving a peak response.
Claim 6
Dependent Claim
15 words
A system according to claim 1 in which all of said filters have equal Q.
Claim 7
Dependent Claim
32 words
A system according to claim 3 in which said peaking filters have inputs and outputs all connected in Parallel, the outputs of said filters being summed together in a single summing amplifier.
Claim 8
Independent Claim
131 words
A system for equalizing an audio sound transducer system with an environment adapted to receive the sound generated by said sound system comprising, meanS for generating a signal source comprising a comb of spectral frequencies in the audio range, means for feeding said comb of frequencies into the audio sound tranSducer system for broad ast into the environment, a plurality of contiguous narrow band filters substantailly covering the band of said comb of spectral frequencies, means for detecting and feeding said comb of spectral frequencies through said plurality of narrow band filters, means for measuring the spectral power in the bandwidth of at least one of said filters and deriving a voltage as a function of the measured power, and means for comparing the derived voltage againSt a known voltage reference.
Claim 9
Independent Claim
131 words
A system for equalizing an audio sound transducer system with an environment adapted to receive the sound generated by said sound system comprising, meanS for generating a signal source comprising a comb of spectral frequencies in the audio range, means for feeding said comb of frequencies into the audio sound tranSducer system for broad ast into the environment, a plurality of contiguous narrow band filters substantailly covering the band of said comb of spectral frequencies, means for detecting and feeding said comb of spectral frequencies through said plurality of narrow band filters, means for measuring the spectral power in the bandwidth of at least one of said filters and deriving a voltage as a function of the measured power, and means for comparing the derived voltage againSt a known voltage reference.
Claim 10
Dependent Claim
31 words
A system according to claim 7 which includes separate means for controlling the gain of each filter whereby the derived voltage from each filter is equal to said known voltage reference.
Claim 11
Dependent Claim
72 words
A system according to claim 7 which includes a rectifier for rectifying the complex waveform output of each filter, a square law network for connecting the rectified output into a signal indicative of power whereby the output is independent of waveform amplitude, and means for integrating the output of said square low network whereby a voltage is produced which is a function of the spectral power in the bandwidth of said filter.
Claim 12
Independent Claim
158 words
A system for equalizing an audio sound transducer system with an environment adapted to receive the sound generated by said sOund system comprising, means forgenerating a signal source comprising a comb of spectral frequencies in the audio range, means for filtering said generated comb of spectral frequencies with a tunable bandpass filter having a given bandpass transfer function, means for feeding said filtered comb of frequencies into the audio sound transducer system for broadcast into the environment, a generated band of contiguous narrow band peaking filters substantially covering the band of said comb of spectral frequencies, means for detecting and feeding said filtered comb of spectral frequencies through said plurality of narrow band filters, meanS for measuring the total spectral power in the output of the plurality of said filters, and means for controlling the power output of the peaking filter in said bank of filters having the same bandpass transfer function used to filter the transmitted signal.
Claim 13
Independent Claim
158 words
A system for equalizing an audio sound transducer system with an environment adapted to receive the sound generated by said sOund system comprising, means forgenerating a signal source comprising a comb of spectral frequencies in the audio range, means for filtering said generated comb of spectral frequencies with a tunable bandpass filter having a given bandpass transfer function, means for feeding said filtered comb of frequencies into the audio sound transducer system for broadcast into the environment, a generated band of contiguous narrow band peaking filters substantially covering the band of said comb of spectral frequencies, means for detecting and feeding said filtered comb of spectral frequencies through said plurality of narrow band filters, meanS for measuring the total spectral power in the output of the plurality of said filters, and means for controlling the power output of the peaking filter in said bank of filters having the same bandpass transfer function used to filter the transmitted signal.
Claim 14
Dependent Claim
40 words
A system according to claim 10 in which said means for filtering said generated comb of spectral frequencies is a tunable bandpass filter having the same Q and bandpass characteristics as each of said filters in said bank of filters.
Claim 15
Independent Claim
176 words
A method of equalizing a room environment with an audio sound generating system that comprises the steps of first generating a signal source comprising a comb of spectral frequencies in the audio range, then filtering said generated comb of spectral frequencies with a bandpass filter having a given bandpass transfer function, then broadcasting said filtered signal through the audio sound generating system, then detecting and feeding said detected signal through a bank of a narrowband peaking filters each having substantially the same transfer function as the filter used to filter the original signal source, then measuring the total spectral power in the combined output of the bank of filters, then adjusting the gain of the filter in the bank of filters that is the same as the filter used to filter the original signal source, then tuning the bandpass filter to a new bandpass frequency and adjusting the gain of the filter in the bank of filters having the same corresponding bandpass frequency, and then repeating the process until the total spectral power is substantially fLat.
Claim 16
Independent Claim
176 words
A method of equalizing a room environment with an audio sound generating system that comprises the steps of first generating a signal source comprising a comb of spectral frequencies in the audio range, then filtering said generated comb of spectral frequencies with a bandpass filter having a given bandpass transfer function, then broadcasting said filtered signal through the audio sound generating system, then detecting and feeding said detected signal through a bank of a narrowband peaking filters each having substantially the same transfer function as the filter used to filter the original signal source, then measuring the total spectral power in the combined output of the bank of filters, then adjusting the gain of the filter in the bank of filters that is the same as the filter used to filter the original signal source, then tuning the bandpass filter to a new bandpass frequency and adjusting the gain of the filter in the bank of filters having the same corresponding bandpass frequency, and then repeating the process until the total spectral power is substantially fLat.
Claim 17
Dependent Claim
77 words
A sound measuring system comprising: means for generating a signal source comprising a comb of spectral frequencies in the audio range, means for feeding said comb of frequencies into an audio sound transducer system for broadcast into surrounding environment, means for detecting and feeding said received comb of spectral frequencies through a tunable bandpass filter having a given bandpass transfer function, and means for measuring the total spectral power in the output of said tunable bandpass filter.
Claim 18
Dependent Claim
77 words
A sound measuring system comprising: means for generating a signal source comprising a comb of spectral frequencies in the audio range, means for feeding said comb of frequencies into an audio sound transducer system for broadcast into surrounding environment, means for detecting and feeding said received comb of spectral frequencies through a tunable bandpass filter having a given bandpass transfer function, and means for measuring the total spectral power in the output of said tunable bandpass filter.
Claim 19
Dependent Claim
83 words
A sound measuring system comprising: meanS for generating a signal source comprising a comb of spectral frequencies in the audio range, means for feeding said comb of frequencies into an audio sound transducer system for broadcast into the surrounding environment; a plurality of filters substantially covering the band of said comb of spectral frequencies, means for detecting and feeding said received comb of spectral frequencies through said plurality of filters, and means for measuring the spectral power in the output of said filters.
Claim 20
Dependent Claim
83 words
A sound measuring system comprising: meanS for generating a signal source comprising a comb of spectral frequencies in the audio range, means for feeding said comb of frequencies into an audio sound transducer system for broadcast into the surrounding environment; a plurality of filters substantially covering the band of said comb of spectral frequencies, means for detecting and feeding said received comb of spectral frequencies through said plurality of filters, and means for measuring the spectral power in the output of said filters.
References Cited (Backward Citations)
US3256391A
Cited
US3624298A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-05-07 | 1976-11-06 | 1977-05-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-05-07 | 1980-11-06 | 1981-05-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-05-07 | 1984-11-06 | 1985-05-08 | $7700.00 | Window Closed / Lapsed |