Abstract: An electrocardiogram enhancement system and apparatus is provided. Small amplitude, high frequency notches associated with myocardial disease and arrhythmias can be recorded by conventional chart recorders. In addition, the notches are clearly visible in the recorded waveform for visual detection and analysis of the notches by medical personnel.In the system of the present invention electrocardiogram signals having small amplitude, high frequency notches are enhanced; first, by selectively amplifying the notches while keeping the amplitude of the remainder of the waveform constant and, second, by uniformly expanding the signal in the time domain wherein the inter-component frequency and inter-component phase relationships are maintained.

Abstract: A microprocessor based sound enhancement system in which frequencies outside of the auditory range of the human ear are translated into sound within the auditory range by translating each frequency component of the entire frequency spectrum of the input signal by a time scale compression factor. Preferably, a microprocessor transforms an electrical signal corresponding to the input signal into a frequency spectrum signal comprising frequency components having frequency, phase, and amplitude elements by performing a fast Fourier transform (FFT) operation on the input signal. The frequency components of this transformed signal are translated and the resulting translated frequency spectrum signal is transformed into a time varying output signal by performing an inverse FFT operation on the translated frequency spectrum signal. When heart pulses or similar periodic waveforms are monitored, the pulse rate of the signal is maintained in the output signal.