Connecting high-power jet noise characteristics with human annoyance: Physical characterization

Physical characterization of annoying components of jet noise will aid in future noise mitigation efforts. Crackle perception is a significant contributor to annoyance produced by supersonic jet noise and is related to the reception of acoustic shocks. The skewness of the pressure time derivative, or derivative skewness, is sensitive to the presence of acoustic shocks and has been shown through listening studies to be indicative of crackle perception. Extensive measurements of a tied-down high-performance military aircraft allow for the examination of spatial variation and source characterization of events related to crackle perception in the field. A variety of factors contribute to the derivative skewness in the field, such as source-receiver distance, apparent source origin, or whether a microphone is placed on or elevated off the ground. Spatially, the derivative skewness often peaks in the maximum radiation region, however, deviations exist at lower engine conditions with sudden increases in derivative skewness in the aft region. An event-based beamforming method is implemented to examine the source region, with resulting directivities lending insight into far-field crackle perception. Characterization of crackle perception using derivative skewness as an indicator will increase understanding of mechanisms contributing to jet noise annoyance. [Work Supported by AF SBIR Program.]