[Effect of acoustic stimulation parameters on human appreciation of changes in distance from a sound source]

Minimal time necessary for appearance of sensation of approaching or withdrawing of the amplitude-impulse-modulated sound was 0.3--0.4 sec at changing the intensity from minimal to maximal within the range of 30--60 dB over the threshold of rhythmic series determination (10--50 Hz). The number of short lengths of tones or noises in the series within this time epoch should be not less than three. The effect of the value of carrying frequency of the series lengths upon the sensation of approaching or withdrawing is only evident within the range of those temporal parameters of the signal which accompanied change of criterion of estimation of the sound quality. Further shortening of the signal leads to substitution of the criterion for estimation of stimulus position for the criterion of sound accentuation at a tonal carrier and for the criterion of consonant-likeness at a noise carrier. The downward frequency modulation from the initial frequency at a growing amplitude enhances the sensation of "approaching", the upward modulation enhances the sensation of source "withdrawing", as compared with the constant frequency or the frequency modulation of opposite sign.