Abstract: A method for fitting a hearing compensation device comprises selecting a plurality of loudness levels for a plurality of frequencies and comparing each loudness level for each frequency for perceived sameness. The loudness levels may then be adjusted as needed to achieve perceived sameness across the frequency spectrum. A gain curve for each frequency is calculated from the selected plurality of loudness levels.

Abstract: A method for fitting a hearing compensation device comprises selecting a plurality of loudness levels for a plurality of frequencies and comparing each loudness level for each frequency for perceived sameness. The loudness levels may then be adjusted as needed to achieve perceived sameness across the frequency spectrum. A gain curve for each frequency is calculated from the selected plurality of loudness levels.

Abstract: A hearing compensation system for the hearing impaired comprises an input transducer for converting acoustical information at an input to electrical signals at an output, an output transducer for converting electrical signals at an input to acoustical information at an output, a plurality of bandpass filters, each bandpass filter having an input connected to the output of said input transducer, a plurality of AGC circuits, each individual AGC circuit associated with a different one of the bandpass filters and having an input connected to the output of its associated bandpass filter and an output connected to the input of the output transducer. The bandpass filters and AGC circuits may be divided into two processing channels, one for low frequencies and one for high frequencies and may drive separate audio transducers, one configured for maximum efficiency at low frequencies and one configured for maximum efficiency at high frequencies.

Abstract: A hearing compensation system comprises an input transducer for converting acoustical information at an input thereof to electrical signals at an output thereof, a differential analog-to-digital converter sampling the electrical signals output from the input transducer at an input thereof and outputting differential signal samples at an output thereof, a digital signal processing circuit having an input connected to the output of the differential analog-to-digital converter and operating on the differential signal samples to form processed differential signal samples at an output thereof, and an output transducer for converting electrical signals at an input thereof to acoustical information at an output thereof, the processed differential signal samples coupled to the input of the output transducer.

Abstract: A hearing compensation system for the hearing impaired comprises an input transducer for converting acoustical information at an input to electrical signals at an output, an output transducer for converting electrical signals at an input to acoustical information at an output, a plurality of bandpass filters, each bandpass filter having an input connected to the output of said input transducer, a plurality of AGC circuits, each individual AGC circuit associated with a different one of the bandpass filters and having an input connected to the output of its associated bandpass filter and an output connected to the input of the output transducer.

Abstract: A hearing compensation system for the hearing impaired comprises an input transducer for converting acoustical information at an input to electrical signals at an output, an output transducer for converting electrical signals at an input to acoustical information at an output, a plurality of bandpass filters, each bandpass filter having an input connected to the output of said input transducer, a plurality of AGC circuits, each individual AGC circuit associated with a different one of the bandpass filters and having an input connected to the output of its associated bandpass filter and an output connected to the input of the output transducer.

Abstract: A multistage data compression system includes an encoder for receiving input data sequences from a data source, where the encoder comprises two or more quantizer stages, each stage having a memory for storing an established set of codewords preselected such that the sum of different combinations of codewords, one for each stage, is representative of likely to occur input data sequences. Each codeword of each stage has a respective index associated therewith. The encoder operates to select a codeword from at least two of the stages such that the sum of the selected codewords is a closer match to each input sequence than any other sum of codewords formed from the selected stages. When the codewords of interest are determined, the indices of those codewords are retrieved. These indices may then be transmitted to another location, stored in memory or otherwise processed. The system also includes a decoder coupled to the transmission channel, memory, or other mechanism which operates on the indices.

Abstract: An apparatus and technique for enhancing the hearing capabilities of persons by providing a device which is a model of the desired hearing characteristic of the persons.

Abstract: An electronic system for processing sampled data input signals includes an electronic memory which stores a set of preprocessed vectors V.sub.1 f(m, . . . ) thru V.sub.N *f(m, . . . ) where f(m, . . . ) is a sampled data function, having any number of dimensions m, . . . . * is a convolution operator, and V.sub.1 thru V.sub.N are a finite set of N unprocessed vectors each of which represents an anticipated group of input signal samples.

Abstract: Synthetic aperture radar (SAR) images are formed by storing in electronic memory possible outputs of a lossy data compressor, f.sub.1,1 [m], f.sub.1,2 [m], . . . f.sub.1,P [m], where f.sub.1,i [m] represents a segment of the unprocessed radar return; by storing range-correlated segments of the SAR data, g.sub.1,1 [m], g.sub.1,2 [m], . . . g.sub.1,P [m], where g.sub.1,i [m] is the range-correlated version of f.sub.1,i [m]; by storing all possible outputs of a second lossy data compressor, f.sub.2,1 [n], f.sub.2,2 [n], . . . f.sub.2,Q [n], where f.sub.2,i [n] represents a segment of the range-correlated SAR image; and by storing segments of the range-azimuth focussed SAR image data, g.sub.2,1,m [n],g.sub.2,2,m [n], . . . g.sub.2,Q,m [n], where g.sub.2,i,m [n] represents a segment of the SAR range-azimuth focussed image. Thereafter, a sequence of separate radar pulses are transmitted from an aircraft and the return signal is sampled and placed in an array. Vectors of the array are compared with segments f.sub.

Abstract: An adaptive noise suppressor for providing noise filtered signals. The noise suppression device employs a vector gain .mu. for the weights of the filter wherein the vector .mu. is selected for each frequency bin to be inversely proportional to the power spectrum. A projection operator is utilized to remove the effects of circular convolution to produce a linear convolution result wherein the weights are readjusted in a manner to minimize the difference between the input signal and the filter output signal, thereby minimizing the error signal to produce a noise suppressed signal in the filtered output. A frequency suppression device utilizes the same principles of the vector .mu. and projection operator, but the output is taken from the error output of the filter.

Abstract: An adaptive detector comprises an adaptive linear prediction filter (ALPF) nd a detection processor.The adaptive filter comprises an input filter, adapted to receive an input signal x(k) and delay it by a time .DELTA.. An L-point, or L-tap, adaptive filter has an input connected to the output of the input filter, a signal r(k) appearing at the output of the filter. A means for summing has two inputs, one for receiving the signal x(k) and the other for receiving an inverted signal from the adaptive filter, the output of the summer being an error signal .epsilon.(k). A feedback amplifier, whose input is connected to the output of the summer, takes a portion 2.mu., of the output signal .epsilon.(k) and feeds it back to the adaptive filter, thereby modifying the tap weights of the adaptive filter.The detection processor comprises a circuit, whose input is connected to the output of the adaptive filter, to receive the signal r(k), for performing a K-point discrete Fourier transform (DFT) on the signal r(k).

Abstract: An input signal X(j) is fed directly to the positive port of a summing function and is simultaneously fed through a parallel channel in which it is delayed, and passed through an adaptive linear transversal filter, the output being then subtracted from the instantaneous input signal X(j). The difference, X(j)-Y(j), between these two signals is the error signal .epsilon.(j). .epsilon.(j) is multiplied by a gain .mu. and fed back to the adaptive filter to readjust the weights of the filter. The weights of the filter are readjusted until .epsilon.(j) is minimized according to the recursive algorithm: ##EQU1## where the arrow above a term indicates that the term is a signal vector. Thus, when the means square error is minimized, W.sub.(j+1) =W.sub.(j), and the filter is stabilized.