Most likely altitude. I recall that they used to practice flying at low altitude. Much more interesting than our anecdata is probably the Oklahoma City Sonic B

Most likely altitude. I recall that they used to practice flying at low altitude. Much more interesting than our anecdata is probably the Oklahoma City Sonic Boom study: https://en.wikipedia.org/wiki/Oklahoma_City_sonic_boom_tests https://en.wikipedia.org/wiki/Oklahoma_City_sonic_boom_tests > the NORC reported that 73% of subjects in the study said that they could live indefinitely with eight sonic booms per day, while 25% said that they couldn't. About 3% of the population telephoned, sued, or wrote protest letters, but Oklahoma City surgeons and hospitals filed no complaints. However, with the city population at 500,000, that 3% figure represented 15,000 upset individuals. There were 9,594 complaints of damage to buildings, 4,629 formal damage claims, and 229 claims for a total of $12,845.32, mostly for broken glass and cracked plaster.