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: 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.