Conductive Loss: Impairment of hearing due to the failure of the sound pressure wave to reach the cochlea through the normal air-conduction channels (outer or middle ear); the inner ear is usually normal.

Sensorineural Loss: Hearing impairment resulting in the inner ear or along the nerve pathway from the inner ear to the brain stem; may be cochlear or retrocochlear, depending on the site of the lesion.

Mixed Loss: Combination of conductive and sensorineural losses.

Functional Loss: Auditory impairment for which no organic basis can be determined or inferred.

Industrial Loss: Loss of hearing sensitivity as a result of relatively long exposure to industrial noise.

Noise-Induced Loss (Occupational): Hearing impairment which develops gradually from continuous exposure to noise which is above acceptable levels.