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4882762 |
Multi-band programmable compression system
A programmable low voltage multi-band compression system suitable for use with hearing aids is described. Received audio signals are processed by a band split filter which separates the received...
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4882761 |
Low voltage programmable compressor
A programmable low voltage compressor circuit suitable for use with hearing aids is described. The compressor has a continuously variable compression ratio wherein the gain of the compressor may be...
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4868880 |
Method and device for compensating for partial hearing loss
A method and device for compensating for partial hearing loss by converting a time domain signal corresponding to a sound into a series of digital component values in the frequency domain,...
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4868881 |
Method and system of background noise suppression in an audio circuit particularly for car radios
To improve the fidelity of reproduction of automobile radios during conditions of extraneous in the passenger compartment, noise signals are derived, for example from a microphone installed in the...
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4864627 |
Microphone mixer with gain limiting and proportional limiting
A sound mixing control system applicable to recording, broadcast and sound reinforcement systems. The gain provided for each input channel through the system is monitored, and whenever the sum of...
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4862118 |
Signal processing system using a compressor and an expander
In a signal processing system used for recording and reproducing acoustic signals, a compressor comprises a first detector for detecting an output signal from an amplifier by a first time constant,...
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4860366 |
Teleconference system using expanders for emphasizing a desired signal with respect to undesired signals
A teleconference system comprises a plurality of microphones and a plurality of expanders connected respectively thereto for expanding the outputs of the microphones. A summing ammplifier produces...
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4856068 |
Audio pre-processing methods and apparatus
A lower threshold for dynamic range compression and clipping is allowed by sinusoidal estimation and phase adjustment of the original speech signal to obtain a lower Peak to RMS ratio. A sinusoidal...
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4853963 |
Digital signal processing method for real-time processing of narrow band signals
A digital signal processing method for real-time processing of narrow band signals to provide for reconstitution of dynamic amplitude and harmonics beyond the passband. The method utilizes a...
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4852167 |
FMX stereophonic receiver
An FMX stereophonic receiver receives an FMX stereophonic broadcast signal which includes a stereo sum signal, an uncompressed stereo difference signal, and a compressed stereo difference signal...
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4843626 |
Multiband limiter with automatic limiting threshold (ALT) compensation
A multiband audio frequency signal limiting apparatus suitable for use in a wide range of applications is disclosed. An input signal is divided into discrete frequency bands (any practical number...
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4841573 |
Stereophonic signal processing circuit
A stereophonic signal processing circuit is designed to be provided with a pair of level compression circuits compressing peak levels of a pair of stereophonic input signals into 1/2 power each, an...
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4829270 |
Compansion system
An improved compansion system that more effectively increases the dynamic range of other circuit elements. The system includes both a compression circuit to limit the input signal amplitude for a...
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4823392 |
Compressor
In a compressor for controlling the dynamic range of audio signals which comprises an operational amplifier and a gain-controlled amplifier connected in inverse parallel with the operational...
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4815142 |
Noise reduction device in an electroacoustic system
The device comprises at least one correction circuit interposed in the electroacoustic system and comprising a band-pass filter receiving an input signal, a compressor limiter circuit connected to...
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4809328 |
FM/FMX stereophonic receiver
An FM/FMX stereophonic receiver is capable of receiving an FM or an FMX stereophonic broadcast signal. The FM stereophonic broadcast signal includes a stereo sum signal and stereo difference...
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4803732 |
Hearing aid amplification method and apparatus
An amplification circuit for hearing aids performs independent amplification of different frequency bands of the signal generated by a microphone of the hearing aid, to match the loss of hearing of...
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4792977 |
Hearing aid circuit
A hearing aid that is compact and efficient and that provides a high degree of control over its frequency response and also over its output level versus input level characteristic. The frequency...
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4771464 |
FM stereophonic broadcasting system utilizing simultaneous companding and modulation/demodulation
An FM stereophonic broadcasting system incorporating companding of the difference signal in which the broadcast signal includes both the usual difference signal and a compressed version of the...
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4769841 |
Receiver for compatible FM stereophonic system utilizing companding of difference signal
In the receiver of an FM stereo broadcasting system which transmits both the usual stereo difference signal S and a compressed version S' of the difference signal compressed according to a...
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4761816 |
Digital level detecting circuit
A digital level detecting circuit for controlling amplitudes of digital audio signals is disclosed, which includes a circuit for generating an attack response of output control signals based on...
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4760602 |
Variable preemphasis/deemphasis network
A variable preemphasis/deemphasis network is disclosed which is coupled between audio input and output terminals. The network exhibits a family of transfer function response characteristics which...
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4759071 |
Automatic noise eliminator for hearing aids
A noise elimination circuit, especially for a hearing aid, which removes all sound below a predetermined level and transmits a compressed sound range for all sounds above a predetermined level. The...
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4747142 |
Three-track sterophonic system
In a stereophonic reproduction system, a true center-channel signal is derived by combining the left and right signals into a monophonic signal, and canceling and overriding this monophonic signal...
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4741039 |
System for maximum efficient transfer of modulated energy
A signal processing system is disclosed for processing dynamically varying intelligence-carrying signals represented by different frequencies by transferring these signals within a pass band...
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4741018 |
Speakerphone using digitally compressed audio to control voice path gain
A mobile radiotelephone (120) includes a microcomputer (220), speakerphone control circuitry (106) and mobile radio (112). Mobile radio (112) includes a transmitter (242), receiver (244) and a...
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4739514 |
Automatic dynamic equalizing
An automatic dynamic equalizer includes left and right input terminals, an input adder and left and right output adders. The left and right input terminals are connected to inputs of the input...
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4736434 |
MOSFET analog signal squaring circuit
A MOSFET analog signal squaring circuit is disclosed. A first MOSFET has a source electrode coupled to a bias voltage source, a gate electrode coupled to an input terminal, and a drain electrode...
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4731852 |
Method to electronically clarify sound or picture information and an arrangement to carry out the method
A method for electronically clarifying sound or picture information and an arrangement for carrying out the method. It is previously known to generate harmonics and subharmonics of a useful signal...
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4726067 |
Method of and apparatus for extending the useful dynamic range of digital-audio systems
A method of (and apparatus for) extending the useful dynamic range of an audio reproduction system. An input acoustic signal in the audible range is transduced to form an analog electric signal...
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4718099 |
Automatic gain control for hearing aid
A hearing aid having signal compression characteristics that adapt to the environment of the sound field in which it is operative in which an automatic gain control signal processor is responsive...
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4704726 |
Filter arrangement for an audio companding system
A companding system for a television audio apparatus includes a compressor and an expander for stereo difference signals. The compressor provides variable preemphasis of high frequency signal...
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4704727 |
Low noise and distortion FM transmission system and method
An FM transmission system and method in which a gain control signal is generated and used to encode the audio signal in accordance with a predetermined compression curve. At the receiver the gain...
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4701953 |
Signal compression system
A signal compression system includes a plurality of channels. A plurality of these channels include a bandpass filter (for filtering out all but a portion of an input signal), an intensity detector...
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4696044 |
Dynamic noise reduction with logarithmic control
DC signals for controlling variably controlled filters for input audio frequency signals are derived by filtering the input signal to reduce its level in response to variations in intensity and...
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4683449 |
Noise reduction compression system controlled by compressed output components which are in-band
A noise reduction system which is unaffected by bandwidth limitations of the transmission system with which the noise reduction system is employed. The noise reduction system is of a type including...
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4677645 |
Audio signal transmission system having noise reduction means
An audio signal transmission system having a noise reduction circuit, which includes a transmission medium such as a magnetic tape to be used to transmit a digital signal converted from an input...
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4674122 |
Encoding for the FMX companding system
Improved FMX Companding apparatus for FM transmitter. A pilot subsystem which is substantially identical to the FMX audio path is used to develop a control signal which provides amplitude control...
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4661981 |
Method and means for processing speech
A method of and apparatus for processing audio signals in which a measure of amplitude of audio signals in a selected time period is obtained. The audio signals for the selected time period are...
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4661851 |
Apparatus for reducing the effect of noise interference in audio companding system
A companding system for a television audio apparatus includes a compressor and an expander for stereo difference or second audio program signals. The compressor provides variable preemphasis of...
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4630302 |
Hearing aid method and apparatus
Method and apparatus for aiding hearing are disclosed comprising an automatic gain control unit which includes a first section for increasing the amplitude of input signal segments that are below a...
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4627094 |
Electronic audio signal processor
In an electronic audio signal processor suitable for electrical instruments such as electrical guitars, there is provided an improved pre-amplifier and compressor circuit which compresses the...
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4611231 |
Signal processing apparatus for a video signal
A video signal processing apparatus has an input terminal for receiving an input video signal and a delay line for delaying the input video signal. A first transmission circuit processes the video...
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4609878 |
Noise reduction system
A noise reduction system including a signal path (34) between an input terminal (12) and an output terminal (36), a voltage control amplifier (38) and a control path (40) between the input terminal...
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4602381 |
Adaptive expanders for FM stereophonic broadcasting system utilizing companding of difference signal
A stereophonic broadcasting system incorporating companding of the difference signal in which both the usual difference signal and a compressed version of the difference signal are transmitted to...
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4562591 |
Digital dynamic range converter
A digital dynamic range converter of the forward control type for varying the dynamic range of a digital audio signal constituted by a sequence of audio signal samples. Each audio signal sample...
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4551853 |
Apparatus for processing speech in radioelectric transmitter/receiver equipment suitable for transmitting and receiving speech
Apparatus for processing speech in radioelectric transmitter/receiver equipment is adapted to transmitting and receiving speech. The apparatus comprises a compression circuit for compressing the...
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4550425 |
Speech sampling and companding device
An analog speech signal is sampled of a nominal rate of 6 kilohertz and digitized in a Mu-Law Encoder. The digital output of the Mu-Law Encoder is converted by a microprocessor performing table...
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4550426 |
Method and means of detecting the presence of a signal representing voice and of compressing the level of the signal
A circuit that combines the functions of audio compression and voice detection comprises an amplifier in a negative-feedback configuration in which the feedback signal is the product of the output...
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4538297 |
Aurally sensitized flat frequency response noise reduction compansion system
A flat frequency response compansion noise reduction system employs both input signal and control signal preemphasis and deemphasis in its encoder and decoder networks respectively. The linear...
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