Influences of low-frequency energy and testing environment on annoyance responses to supersonic aircraft noise when heard indoors.

The research reported is part of a larger effort to develop models to predict community response to transient sounds, including sonic booms. Such models can be used along with aircraft sound predictions to guide the design of supersonic aircraft to produce generally acceptable sounds. A test was conducted to examine the influence of low frequencies on people's responses to recorded and simulated booms and other environmental transients, heard indoors over earphones. The results of this test and a companion test conducted in a sonic boom simulator were compared to see if the playback environment affected responses. Annoyance models were also examined. E-weighted Sound Exposure level (ESEL) was the sound metric most highly correlated to mean annoyance with B-weighted Sound Exposure Level (BSEL) and Perceived Level performing similarly. Predictions were improved by including Heaviness, Duration, and rate of change of Loudness in models with a loudness metric. Models were also estimated by using the average responses from both tests and metrics generated from outdoor versions of the sounds. These models also produced accurate annoyance predictions. BSEL was the best single-metric predictor, with ESEL close behind. Including Heaviness, Duration, and rate of change of Loudness resulted in R2 values as high as 0.90.