Two laboratory studies of people's responses to sonic booms and other transient sounds as heard indoors
Manufacturers of business jets have expressed interest in designing and building a new generation of supersonic jets that produce shaped sonic booms of lower peak amplitude than booms created by the previous generation of supersonic aircraft. To determine if these "low" booms are less intrusive and the noise exposure is more acceptable to communities, new laboratory testing to evaluate people's responses must occur. To guide aircraft design, objective measures that predict human response to modified sonic boom waveforms and other impulsive sounds are needed. The current research phase is focused on understanding how people will react to booms when heard inside, and must therefore include considerations of house type and the indoor acoustic environment. A test was conducted in NASA Langley's Interior Effects Room (IER), with the collaboration of NASA Langley engineers. This test was focused on the effects of low-frequency content and of vibration, and subjects sat in a small living room environment. A second test was conducted in a sound booth at Purdue University, using similar sounds played back over earphones. The sounds in this test contained less very-low-frequency energy due to limitations in the playback, and the laboratory setting is a less natural environment. For the purpose of comparison, and to improve the robustness of the human response prediction models, both sonic booms and other more familiar transient sounds were used in the tests. In the Purdue test, binaural simulations of the interior sounds were included to compare responses to those sounds with responses to playback of binaural recordings taken in the IER. Major conclusions of this research were that subject responses were highly correlated between the two tests, and that annoyance models including Loudness, maximum Loudness Derivative, Duration, and Heaviness terms predicted annoyance accurately.^
Patricia Davies, Purdue University.
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