Human echolocation: Acoustic gaze for burst trains and continuous noise. (May 2016)

• Record Type: Journal Article
• Authors: Schenkman, Bo N.; Nilsson, Mats E.; Grbic, Nedelko
• Is Part Of: Applied acoustics. Volume 106(2016)
• Page Start: 77
• Page End: 86
• Publication Date: 2016-05
• Subjects: Blind -- Echolocation -- Bursts -- Noise -- Orientation; Acoustical engineering -- Periodicals; Periodicals; 620.2
• DOI: 10.1016/j.apacoust.2015.12.008
• Languages: English
• ISSNs: 0003-682X

Abstract

Highlights: Human echolocation – important to avoid overlap of echo with next emitted sound. Acoustic gaze – as for animal echolocation, likely also in human echolocation. Continuous noise, at some conditions, gives higher echolocation detection than short bursts. Blind persons should not emit too tightly spaced bursts in a time interval when echolocating. Abstract: This study explored the ability of blind and sighted listeners to detect reflections, "echoes", of burst trains or continuous noise. Echo detection was compared by presenting 5 ms bursts, rates from 1 to 64 bursts, with a continuous white noise, all during 500 ms. Sounds were recorded in an ordinary room through an artificial binaural head, the loudspeaker 1 m behind it. The reflecting object was an aluminum disk, diameter 0.5 m, placed at 1 m. The sounds were presented to 12 blind and 26 sighted participants in a laboratory using a 2-Alternative-Forced-Choice methodology. The task was to detect which of two sounds contained an echo. In Experiment 2, 1.5 m distance sounds were presented to the blind only. At 1 m, detection for the blind increased up to 64 bursts/500 ms, but for the sighted up to 32 bursts. At 1.5 m, the peak performance for the blind was at 32 bursts. At the 1 m, but not at the 1.5 m distance, the blind performed best with continuous white noise. The overlap in time of signal and echo at 1 m for 64 bursts was 60%, but at 1.5 m 82%. Avoiding an overlap between emitted bursts and returning echoes seems important for echolocation, indicating that an acoustic gaze, analogous to in echolocating animals, may also exist in humans.