A Laboratory Study of Subjective Response to Sonic Booms Measured at White Sands Missile Range

this paper is to quantify subjective loudness response to a set of signatures selected from those recorded at White Sands Missile Range. The selected signatures represented several shapes that sonic booms may take when modified by turbulence. These shapes have been categorized by previous investigators (see ref. 8) as : N-waves, Peaked waves (booms with one or more peaks on both front and rear shocks), Rounded waves (booms with rounded front and rear shocks), and "U-shaped" waves (booms having two strong positive-going peaks). An additional category, labeled "Intermediate" waves, which are characterized by three or more distinct shocks, was also included. Several metrics were identified by the previous investigators (refs. 1-4) as being good loudness estimators for the idealized outdoor boom signatures. These metrics were: Steven's Mark VII Perceived Level, Zwicker Loudness Level, and A-weighted sound exposure level. Each of these effectively predicted the loudness of a wide range N-wave and front-shock minimized boom shapes. An additional objective of this paper was to investigate the performance of these metrics for the White Sands booms. EXPERIMENTAL METHOD Sonic Boom Simulator The experimental apparatus used in this study was the Langley Research Center's Sonic Boom Simulator. Construction details, performance capabilities, and operating procedures of the simulator are given in reference 1. The simulator, shown in Figure 1, is a person-rated, airtight, loudspeaker-driven booth capable of accurately reproducing user-specified sonic boom waveforms at peak sound pressure levels up to approximately 138 dB. Input waveforms are "predistorted" to compensate for nonuniformities in the frequency response characteristics of the booth and sound reproduction system. Test Subj..