The intensity of a stimulus that will just barely produce a sensation. In pure tone audiometry, threshold is defined as the minimal hearing level at which an individual is able to respond to a tone at least fifty per cent of the time. It is this minimal hearing level that is plotted on an audiogram indicating an individual's best level of hearing for that frequency.
the lowest intensity of sound that can be heard. Although threshold of hearing is defined as 0 dB, it varies with different frequencies.
For a given listener, the minimum sound pressure level of a specified sound that is capable of evoking an auditory sensation. The sound reaching the ears from other sources is assumed to be negligible (IEC 84).