Human echolocation: Acoustic gaze for burst trains and continuous noise |
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Authors: | Bo N. Schenkman Mats E. Nilsson Nedelko Grbic |
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Affiliation: | 1. CTT – Centre for Speech Technology, Department of Speech, Music and Hearing, Royal Institute of Technology, Stockholm, Sweden;2. Psychological Sciences Research Institute, Université catholique de Louvain, Louvain-la-Neuve, Belgium;3. Department of Psychology, Stockholm University, Stockholm, Sweden;4. Department of Electrical and Information Technology, Lund University, Lund, Sweden |
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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. |
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Keywords: | Blind Echolocation Bursts Noise Orientation |
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