Reducing contaminating noise effects when calculating low-boom loudness levels.

Autor:	Anderson MC; Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, USA., Gee KL; Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, USA., Durrant JT; Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, USA., Loubeau A; Applied Acoustics Branch, NASA Langley Research Center, Hampton, Virginia 23681, USA., Doebler WJ; Applied Acoustics Branch, NASA Langley Research Center, Hampton, Virginia 23681, USA., Klos J; Applied Acoustics Branch, NASA Langley Research Center, Hampton, Virginia 23681, USA.
Jazyk:	angličtina
Zdroj:	The Journal of the Acoustical Society of America [J Acoust Soc Am] 2024 Jun 01; Vol. 155 (6), pp. 3889-3899.
DOI:	10.1121/10.0026436
Abstrakt:	During NASA X-59 quiet supersonic aircraft community response tests, low-boom recordings will contain contaminating noise from instrumentation and ambient acoustical sources. This noise can inflate sonic boom perception metrics by several decibels. This paper discusses the development and comparison of robust lowpass filtering techniques for removing contaminating noise effects from low-boom recordings. The two filters are a time-domain Butterworth-magnitude filter and a frequency-domain Brick Wall filter. Both filters successfully reduce noise contamination in metric calculations for simulated data with real-world contaminating noise and demonstrate comparable performance to a modified ISO 11204 correction. The Brick Wall filter's success indicates that further attempts to match boom spectrum high-frequency roll-off beyond the contaminating noise floor are unnecessary and have marginal improvements on final metric calculations. Additionally, the Butterworth filter removes statistical correlation between ambient and boom levels for a real-world flight campaign, adding evidence that these techniques also work on other boom shapes. Overall, both filters can produce accurate metric calculations with only a few hundred hertz of positive signal-to-noise ratio. This work describes methods for accurate metric calculations in the presence of moderate noise contamination that should benefit X-59 and future low-boom supersonic aircraft testing. (© 2024 Acoustical Society of America.)
Databáze:	MEDLINE
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