The effect of supersonic aircraft speed on the penetration of sonic boom noise into the ocean

In 1968 Sawyers presented a theory which predicts the acoustic pressure underwater due to a supersonic aircraft’s sonic boom in the air. The theory has since been validated in laboratory experiments. In the present paper Sawyers’ theory is utilized to predict the effect of a supersonic aircraft’s speed on the penetration of the sonic boom into the water. By taking into account the variation in a sonic boom’s duration as a function of the aircraft Mach number, it is shown that higher aircraft speeds are associated with higher acoustic pressures in the water. For fixed depths of 10 m or less the peak SPL varies less than 6 dB over a wide range of Mach numbers. For greater depths, 100 m for example, increased Mach numbers may increase the SPL by 15 dB or more. The actual levels are always diminished for deeper depths. These observations may be important for evaluating the possible effects of sonic boom noise on marine mammals.