Sonic boom is sufficiently long. A new metric has emerged, known as "perceived" loudness, measured in PLdB. This takes into account the frequency content, rise time, etc. A well-known example is the snapping of one's fingers in which the "perceived" sound is nothing more than an annoyance. The energy range of sonic boom is concentrated in the 0.1–100 hertz frequency range that is considerably below that of subsonic aircraft, gunfire and most industrial noise. Duration of sonic boom is brief; less than a second, 100 milliseconds (0.1 second) for most fighter-sized aircraft and 500 milliseconds for the space shuttle or Concorde jetliner.
Aircraft noise aircraft noise clearly and significantly impairs health. For example, a day-time average sound pressure level of 60 decibels increasing coronary heart disease by 61% in men and 80% in women. As another indicator, a night-time average sound pressure level of 55 decibels increased the risk of heart attacks by 66% in men and 139% in women. Statistically significant health effects did however start as early as from an average sound pressure level of 40 decibels. The Federal Aviation Administration (FAA) regulates the maximum noise level that individual civil aircraft can emit through requiring aircraft to meet certain noise certification standards.