Trading level for number of aircraft immissions: A full‐factorial laboratory design

TLDR: In this paper, an original B737 take-off sound (A•weighted sound pressure level: Lmax=76 dB) was either reduced or amplified by 4.8 dB, achieving constant energy equivalence defined by LeqA=const.

Abstract: To what extent can the number of overflights be increased without enhancing annoyance, if airplanes become softer? An original B737 take‐off sound (A‐weighted sound‐pressure level: Lmax=76 dB) was either reduced or amplified by 4.8 dB. In a 3×3 factorial design, nine groups of ten subjects were exposed for 27 min to 3, 9, or 27 copies of one of these three sounds. Regarding energy equivalence defined by LeqA=const, a 4.8‐dB sound‐pressure reduction compensated for three times the number of the higher level, achieving constant Leq levels in the diagonals of the design. After noise exposure, cardiovascular responses and the subject ratings of loudness, annoyance, and quality of an imagined living area with comparable noise load were analyzed statistically. Comparison of the equal‐energy conditions revealed no difference regarding heart rate and blood pressure, but subjective loudness increased with both level and number, and 27 soft aircraft were rated extremely loud. However, annoyance decreased, when 3 lo...