Technique for Enhancing Signals for Auditory Detection
Robert C. Lummis, Manfred R. Schroeder · The Journal of the Acoustical Society of America · 1969
If a narrow-band signal imbedded in noise is recorded and reproduced at higher speed, then heterodyned to restore the signal to its original frequency, the signal-to-noise ratio measured with a bandpass filter centered on the signal frequency will be increased. This procedure is useful when the human auditory system is to serve as the analyzer and detector, because it permits the signal bandwidth to be matched to the fixed analyzing bandwidth of the ear.