HEARING LEVEL or HEARING THRESHOLD LEVEL
A measured value of an individual's THRESHOLD OF HEARING, expressed in DECIBELs, relative to a specified audiometric standard.
Hearing of speech is considered to be impaired when the hearing level is shifted 25 dB or more, averaged over the 500, 1000 and 2000 Hz frequencies (the region most critical in speech perception). The total impairment level is 1.5 times greater than that for speech. This measurement is not concerned with PRESBYCUSIS, which tends to be considered 'normal'.
See: AUDIOGRAM, AUDIOMETRY, HEARING LOSS, THRESHOLD SHIFT. Compare: INTENSITY LEVEL, LOUDNESS LEVEL, NOISE LEVEL, PERCEIVED NOISE LEVEL, SOUND LEVEL, SOUND PRESSURE LEVEL.