Scaling Human Reactions to the Sound from Aircraft

Studies were undertaken to (determine how “noisy” commercial jet aircraft will sound to people on the ground in comparison to present-day commercial aircraft with reciprocating engines. Three experiments involved the flyover sound made by reciprocating-engine aircraft (a DC-7 and a Super-Constellation) and jet aircraft (a Caravelle, a Comet, and a 707). People were asked to judge the “annoyance” or potential bother-someness of the sounds relative to one another. It was found that the over-all sound pressure level (“C” scale) and the speech interference level (SIL) of the sounds from the aircraft as measured on the ground, either outdoors or indoors, bear little relation to the judgments. The loudness level in phons, the values obtained with the aid of the “equal listener-response curve” of Miller and Beranek, and over-all sound pressure level “A” scale and “P” scale correlate better with the findings. However, the results of the judgment tests are predicted best when the SPL's of the various octave bands are weighted in a newly prescribed manner. This calculation scheme is based on previously published equal-annoyance contours and the procedures developed by Stevens for calculating loudness level.