Effects of Aircraft Noise on an Intelligibility Task

The recorded sounds of three aircraft (T28 propeller airplane, Bell 204B helicopter, and Bell 206 helicopter) flying directly overhead at 300 ft and 900 ft (91.4 m and 274.3 m) were played While subjects engaged in an audiovisual task. The subjects viewed a series of 35-mm color slides of everyday scenes and heard them described by one-word labels. Each label was to be identified as "Right," "Wrong," or "Unheard." The results were in close agreement with previous field studies on the rated "annoyingness" of aircraft sounds and provided no support for the contention that impulsive helicopter noise ("blade-slap") is disruptive in ways not accoullfed for by simple measures of loudness level