Spectral integration time of the auditory localisation system.
For the elevation and front-versus-back hemifield of a sound source to be accurately determined, the sound must contain a broad range of frequencies. Experiment 1 of this study examined the spectral integration time of the auditory localisation system by measuring the accuracy with which frequency-modulated (FM) tones of modulation periods ranging from 0.5 to 200 ms can be localised. For each of the four participants, judgements of sound-source elevation and front-back hemifield were most accurate for a modulation period of 5 ms. Accuracy levels for the 5 ms modulation period approached those for a pink-noise stimulus. This suggests that the spectral integration time of the auditory localisation system is around 5 ms. Supporting evidence for this conclusion was sought in experiment 2, in which two participants localised noise stimuli that had magnitude spectra identical to those of 5 ms equivalent-rectangular-duration samples of the FM tones from experiment 1. For both participants, functions relating localisation error measures (i.e., elevation error and frequency of front-back confusion) to modulation period for spectrally matched noises were similar to those for FM tones.
Martin
Russell L
RL
Air Operations Division, Defence Science and Technology Organisation, P.O. Box 4331, Melbourne 3001, Australia. russell.martin@dsto.defence.gov.au
McAnally
Ken I
KI
D000161:Acoustic Stimulation; D000328:Adult; D001306:Auditory Pathways / Q000502:physiology*; D005260:Female; D019416:Head Movements; D006801:Humans; D008297:Male; D008875:Middle Aged; D013017:Sound Localization; D013997:Time Factors