THE SCIENCE AND APPLICATIONS OF ACOUSTICS - H. H. Arnold ...

226 10. Physiology of Hearing and PsychoacousticsFigure 10.6. Equal loudness contours. (From Peterson, A. P. G. and E. E. Gross. Handbookof Noise Measurement. 1980. Concord, MA: General Radio.)aural response whether or not the fundamental frequency is present. The averageadult male voice carries a fundamental between 120 and 150 Hz and that of atypical adult female lies between 210 and 240 Hz. Yet we generally find it easyto distinguish between male and female voices even though the telephones doesnot transmit frequencies much lower than 300 Hz. Somehow we are able to atoneaurally for the fundamental frequency missing from the signal passing through thetelephone receiver.The spectrum of a sound generates a psychological sensation of quality. Thispermits us to distinguish the difference, say, between a trumpet and an Englishhorn playing the same note. This is because of the differences in their respectivesound spectra (i.e., the frequency content or the presence of overtones), which, inturn, are functions of the complex vibrations and the resonance modes inherentin their respective structures. We are also able to discern different speech soundsbecause of the differences in the sound spectra. Even over the telephone, individualvoices are recognizable because of the differences in their sound spectra.MaskingMasking is said to have occurred when the audibility of a sound is interfered withby the presence of noise or other background sound. The “cocktail party” effect,