The Minimum Audible Movement Distance for Localization of Approaching and Receding Broadband Noise with a Reduced Fraction of High-Frequency Spectral Components Typical of Prebyscusis

Resumo

The minimum audible movement distance was estimated for approaching and receding sound images with a reduced fraction of high-frequency spectral components which reflects an age-related deterioration of auditory perception (presbycusis). Such a reduction can lead to a partial shutdown of the high-frequency binaural auditory mechanism and changes in distance estimation for sound sources positioned at egocentric distances up to 5 m, i.e. in case of making a contact (collision) decision. This study was carried out in free-field conditions using a sound source movement model. The movement was modelled by noise bursts with linearly changing amplitudes, which were emitted by two loudspeakers spaced 3 m apart. The minimum audible movement distance in estimating moving sound images with a reduced fraction of high-frequency signal components was found to be twice as low as for sound images without such a reduction. The data obtained indicate that, provided that the suprathreshold signal encoding mechanisms remain intact, high-frequency level lowering does not increase the minimum audible movement distance.