Human echolocation: Pitch versus loudness information

Document type: Journal Articles
Article type: Original article
Peer reviewed: Yes
Author(s): Bo Schenkman, Mats E. Nilsson
Title: Human echolocation: Pitch versus loudness information
Journal: Perception
Year: 2011
Volume: 40
Issue: 7
Pagination: 840-852
ISSN: 0301-0066
Publisher: Perception
URI/DOI: 10.1068/p6898
ISI number: 000296601200007
Organization: Blekinge Institute of Technology
Department: School of Management (Sektionen för management)
School of Management S- 371 79 Karlskrona
+46 455 38 50 00
Language: English
Abstract: Blind persons emit sounds to detect objects by echolocation. Both perceived pitch and perceived loudness of the emitted sound change as they fuse with the reflections from nearby objects. Blind persons generally are better than sighted at echolocation, but it is unclear whether this superiority is related to detection of pitch, loudness, or both. We measured the ability of twelve blind and twenty-five sighted listeners to determine which of two sounds, 500 ms noise bursts, that had been recorded in the presence of a reflecting object in a room with reflecting walls using an artificial head. The sound pairs were original recordings differing in both pitch and loudness, or manipulated recordings with either the pitch or the loudness information removed. Observers responded using a 2AFC method with verbal feedback. For both blind and sighted listeners the performance declined more with the pitch information removed than with the loudness information removed. In addition, the blind performed clearly better than the sighted as long as the pitch information was present, but not when it was removed. Taken together, these results show that the ability to detect pitch is a main factor underlying high performance in human echolocation.
Subject: Physical Acoustics\General