Clinical implications of a damaged cochlea: pure tone thresholds vs information-carrying capacity.

The pure tone audiogram is an accurate measure of auditory threshold as a function of stimulus frequency. However, it does not provide the complete picture in patients with sensorineural hearing loss (SNHL) because it is not a direct measure of damage to the cochlear epithelium or of the associated limits on information-carrying capacity that restrict word recognition. Diagnostic use of the audiogram leads to the error of viewing SNHL as "dB of hearing loss," which may seem reversible by gain. Cochlear disorders, on the other hand, often give rise to abnormal thresholds because regions are damaged and may best be thought of more in terms of intractable sensory limitations, comparable to vision loss in retinal disease. We argue that word recognition testing at low vs high presentation levels provides a quantification of the cochlea's information-carrying capacity and is a useful predictor of word recognition limits with hearing aids.