Trading level for number in the laboratory: Differential effects of aircraft noise on cardiovascular activation, annoyance, and assessment of quality of life

As aircraft become quieter, the question arises to what extent the decrease in noise is convertable into an increase in the number of flight movements without enhancing psychological and physiological noise effects. Conventional reasoning has it that it suffices to keep constant the energy equivalent noise level. In a 3×3 design combining three number conditions (3/9/27 overflights during 30 min) with three noise level conditions (aircraft types emitting 71/76/81 dB(A) per overflight), this assumption was tested, using three groups of 12 subjects each for the number conditions, and repeated measurements for the level conditions. Comparisons between the equal‐energy conditions (e.g., 3×76 dB vs 9×71 dB) did not show any significant differences regarding systolic and diastolic blood pressure and heart rate. Regarding ratings for annoyance in the lab situation, results were the same with a slight tendency for underenergetic number effects, that means, more but softer aircraft were preferred. However, if the subjects imagined to reside in a region continuously exposed to the experienced noise, quality of living was assessed as slightly more negative for residential areas with nine overflights, and clearly more negative for 27 overflights, though energy was fixed. This suggests overenergetic number effects for living quality beginning at about 18 overflights/h.