Abstract
Supersonic aircraft produce a sonic boom when flying faster than the speed of sound. To rule out detrimental effects for inhabitants of overflown areas, civil supersonic flights (like the Concorde) were only allowed to fly at supersonic speed when over water. Due to the progress in aircraft design, the supersonic boom may be reduced considerably in the future. In this study, listening tests were carried out with a variety of low boom simulations and conventional sonic boom signatures in a similar level range. Participants rated the loudness and the short-term annoyance of 24 sonic boom signals, which differed in terms of the signature shape and maximum pressure but were confined to a range of A-weighted sound exposure levels around 60 dB(A). The results showed main effects of signature and relative level variation as well as an interaction of the two. Correlation coefficients between the ratings and sound exposure levels were highest for A-weighted sound exposure levels compared to other frequency weightings. Contrary to our expectations, the provision of background information about the nature of the presented sound sources had no statistically significant influence on the ratings.
Highlights
The sonic boom level of future supersonic aircraft may be reduced considerably due to the progress in aircraft design.1 Such low sonic boom sounds will be considerably quieter and sound very different compared to conventional sonic booms.2 The evoked sensation and subjective response of human listeners to future low sonic boom signatures are under investigation.3–6 a definitive acoustic measure reflecting the acceptability of low sonic booms is not established yet, and there is a question of how to define it such that the effects on humans are well reflected.2,7Several studies investigated the loudness,8,9 the loudness in combination with acceptability,10,11 the annoyance,3,4,12–15 and the realism16 of sonic boom sounds
The results showed main effects of signature and relative level variation as well as an interaction of the two
Leatherwood and Sullivan found correlation coefficients around 0.96 between A-weighted sound exposure level (ASEL) values and loudness ratings for simulations created from connected straight lines
Summary
The sonic boom level of future supersonic aircraft may be reduced considerably due to the progress in aircraft design. Such low sonic boom sounds will be considerably quieter and sound very different compared to conventional sonic booms. The evoked sensation and subjective response of human listeners to future low sonic boom signatures are under investigation. a definitive acoustic measure reflecting the acceptability of low sonic booms is not established yet, and there is a question of how to define it such that the effects on humans are well reflected.2,7Several studies investigated the loudness, the loudness in combination with acceptability, the annoyance, and the realism of sonic boom sounds. In search of an acoustic measure reflecting human perception, some studies found close correlations between sonic boom ratings and values of the A-weighted sound exposure level (ASEL). Leatherwood and Sullivan investigated the effect of boom shapes for simple simulations constructed from connected straight lines.10 They found correlation coefficients around r 1⁄4 0.96 between the ASEL and loudness ratings for overpressure values between 50 and 125 Pa (1.0 psf and 2.6 psf) and ASEL values between 62 and 90 dB(A), depending on the set of sounds. More recent studies found similar values for coefficients of determination between annoyance ratings and ASEL or perceived level (PL) for simulated low intensity sonic booms and for N-waves with different rise times and filtered impulse signals.. The same authors reported very high correlation coefficients between ASEL values and loudness/annoyance values obtained from magnitude estimation experiments. More recent studies found similar values for coefficients of determination between annoyance ratings and ASEL or perceived level (PL) for simulated low intensity sonic booms and for N-waves with different rise times and filtered impulse signals. Similar results were found for sonic boom sounds with and without rattle when calculated for the actual sound heard by participants (e.g., indoors). Vos investigated the annoyance produced by small, medium-large, and large firearms. He achieved a more precise and unified characterization of the annoyance from impulsive events by using a rating sound level Lr, including level adjustments instead of ASEL values alone
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