Seventy-five decibels is about the loudness of chamber music in a small auditorium. It is just above a normal speaking voice, which is about 65 to 70 decibels. It is just below a telephone dial tone, which registers at 80 decibels.
A decibel is a unit of sound level measurement. Decibels are measured on a logarithmic scale of loudness because human ears detect changes in volume in a non-linear fashion. A difference of 1 decibel is the minimum change in volume. Three decibels difference is a moderate change in volume. A change of 10 decibels is perceived by the listener to be a doubling of volume. Decibels are abbreviated as dB.
The threshold of hearing is zero decibels. A whisper is about 15 to 25 decibels. Background noise is generally about 35 decibels. The level at which sustained exposure might result in hearing loss is 90 to 95 decibels. Ear pain begins when the sound level gets up to 125 decibels. At 140 decibels, even short term exposure can result in permanent damage. This is also the loudest recommended exposure, even with hearing protection. Death of the hearing tissue in the ear occurs at 180 decibels. The loudest sound possible on the decibel scale is 194 decibels.