Auditory Perception in Open Field: Distance Estimation

Report No. ARL-TR-6520
Authors: Kim F. Fluitt; Timothy Mermagen; Tomasz Letowski
Date/Pages: July 2013; 68 pages
Abstract: The purpose of this study was to expand our knowledge about auditory distance estimation at larger distances in an open-field environment in which auditory sensations are affected by meteorological factors, such as wind, temperature, and humidity. Of particular concern are the conditions where visual distance estimation is compromised, and auditory distance estimation has important military implications and contributes to Soldier safety and mission effectiveness. Our goal was accomplished by collecting both acoustic (target sound and noise levels) and meteorological (wind direction and strength, temperature, atmospheric pressure, and humidity) data for each experimental trial. Twenty-four subjects (men and women, ages 1825) participated in this study. Seven types of sounds together with blank (no sound) trials were presented to the listeners. The sounds were delivered from six loudspeakers located 25, 50, 100, 200, 400, and 800 m from the listener. The actual loudspeakers were spread across the field together with 12 additional dummy loudspeaker boxes providing visual uncertainty regarding the sound source location. The results of the study indicate that auditory distance judgments in the open field at 25-m distance and beyond underestimate the actual distances to sound sources regardless of the distance.
Distribution: Approved for public release
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Last Update / Reviewed: July 1, 2013