ABSTRACT
Perception is restored as well as possible on the basis of the signal stream as it preceeds and follows the segment masked by noise. In studying the recognition and classification of sound signals, one should realize that in many practical situations the signals are heard against a background of noise. The signals were generated by a digital computer, converted to analog signals, mixed with noise, and presented to the observer via headphones at a sensation level of about 50 dB. The subjects were instructed to compare the complex tones and to ignore, as best they could, the noise accompanying some signals. The experiments discussed have shown that perception of sound signals is remarkably resistent against interfering noise. Houtgast discovered that, at a low S/N ratio, a single tone with a frequency of nf Hz may suffice to induce a pitch corresponding to f Hz.
