Comparing Lpk, ASEL, PL, and ISBAP for Far-Field Rocket Sonic Booms: Evidence for Perception-Based Metrics

Rocket launches have increased rapidly over the last several years, bringing importance to the metrics used for explaining how humans perceive sonic booms produced by these vehicles. Peak sound pressure level (Lpk) does not account for the rise time and frequency content of booms, making them less reliable in describing human noise perception. In contrast, perception-based metrics such as A-weighted sound exposure level (ASEL), perceived level (PL), and the Indoor Sonic Boom Annoyance Predictor (ISBAP) account for the rise time and spectral content of sonic boom waveforms, more closely resembling how humans hear noise. 

Analysis of a multi-season far-field dataset comprised of Falcon-9 ascent sonic booms (75-155 km) using cross-metric comparisons reveals tight spearman correlations between PL, ASEL, and ISBAP (r≈0.99), while Lpk showed less consistency (r≈66-69). Regression analyses also reveal near-linear relationships between ASEL, PL, and ISBAP (R²≈0.96–0.98) and a weaker relationship between Lpk and the perception-oriented metrics (R²≈0.39–0.53). 

These findings demonstrate that integrated, perception-oriented metrics (PL, ASEL, ISBAP) outperform peak-only measures for assessing sonic boom impacts on human hearing.