Abstract: A circuit and a method for generating modified reference voltages are provided. The reference voltages are modified dependent upon the level of electrical signals received. A series of electrical signals is provided to a reference voltage adjuster. The reference voltage adjuster stores a signal representing either a previous maximum or minimum signal value, and also stores a signal representing a present signal from the series of electrical signals. The reference voltage adjuster then determines the existence of a new maximum or minimum signal value. Upon the determination of the existence of a new maximum or minimum signal value, the average of the new maximum or minimum signal and the previous maximum or minimum signal value is determined. The signal representing the average of the new maximum or minimum signal and the previous maximum or minimum signal value is then provided to a comparator as the new reference voltage.

Abstract: A method is disclosed of modification of parameters of audio signals by dividing a digital signal converted from an original analog signal into sound frames, modifying a pitch and a playing rate of the digital signal within a frame and subsequent successive splicing a last modified frame with a first non-modified frame and calculating the mean absolute error to define the best splicing point in terms of producing minimal or no audible noise such that various sections of sound signals can be spliced together to achieve pitch and playing rate modification.An apparatus is also disclosed for implementing the method, the apparatus comprising input and output amplifiers, a low pass filter at the input and a low pass filter at the output, analog-to-digital and digital-to-analog converters, and a pitch shifting processor.

Abstract: A method is disclosed of modification of parameters of audio signals by dividing a digital signal converted from an original analog signal into sound frames, modifying a pitch and a playing rate of the digital signal within a frame and subsequent successive splicing a last modified frame with a first non-modified frame and calculating a differential mean absolute error to define the best splicing point in terms of producing minimal or no audible noise such that various sections of sound signals can be spliced together to achieve pitch and playing rate modification. An apparatus is also disclosed for implementing the method, the apparatus comprising input and output amplifiers, a low pass filter at the input and a low pass filter at the output, analog-to-digital and digital-to-analog converters, and a pitch shifting processor.

Abstract: A sound generator for storing and reproducing audio signal with reduced memory storage, which is accomplished by: (a) the technique of Adaptive Differential Pulse Code Modulation (ADPCM), and (B) the elimination of silence period from memory storage but regenerating the silence signal at output.