A level of 120 decibels (dB) corresponds exactly to the human pain threshold. At this volume, immediate pain often occurs, and unprotected exposure can cause permanent hearing damage in just a few seconds. 120 dB: A jet taking off (from a distance of about 100 meters), a very close clap of thunder, or a deafening rock concert. Since the decibel scale is logarithmic, an increase of 10 dB is perceived by the human ear as a doubling of loudness. Thus, 120 dB is not merely