Developmental Disorders and Mental Health Disorders

8. Hearing Impairment

Hearing impairment refers to the inability or reduced capacity to receive, conduct, or register auditory stimuli. The function of any specific anatomical part of the auditory system may be compromised due to damage, underdevelopment, or disease.

Hearing is classified into three categories:

• Normal hearing – the hearing threshold for normal sound ranges from 0 to 25 dB.
• Hard of hearing – this category begins above 25 dB and includes mild, moderate, and severe hearing loss up to 90 dB.
• Deafness – any threshold above 90 dB is classified as deafness.

The term 'deafness' is a technical term usually associated with a specific residual level of hearing, where the impairment cannot be overcome solely by using a hearing aid. True (clinical) deafness, which implies no residual hearing in any form, is very rare (URIHO, Hearing Impairments).