Annoyance scales for simulated VTOL and CTOL overflights

Abstract

Annoyance of simulated VTOL and CTOL overflights was measured by magnitude estimation scaling. Forty subjects were presented individually with a series of overflight sounds consisting of a mix of aircraft. L‐1011 arrivals and departures at each of three intensity levels were interleaved with Boeing‐Vertol B‐347 overflights with flight parameters adjusted to produce three subjectively varying levels of “blade slap.” Each of the “blade slap” variations was also presented at three intensity levels. In addition the L‐1011 arrivals and departures were octave filtered (10 dB) at each of three center frequencies: 315, 800, and 1600 Hz. These six “treated” spectra were also presented at three intensity levels. An L‐1011 arrival at 89 dbA was used as the standard called “100.” Each of the 33 stimuli was presented in a different random order to each subject for their judgments. Plotted against dBA helicopters were more annoying than arrivals which were more annoying than departures. Plotted against EPNdB arrivals and departures showed equivalent annoyance, whereas helicopters continued more annoying. Helicopters with varying “blade slap” showed differential annoyance against dbA but were conformed by EPNL. [Work supported by DOT‐FAA and NASA.]