Hearing Aids Mechanical -- See Hearing aids Here are entered works on devices to improve hearing ability. Works on synthetic replicas of the ear used to restore cosmetic harmony to the face are entered under Ear prostheses.
Hearing Disorders -- See Also the narrower term Deafness Here are entered works on the lack of sense of hearing, including the lack combined with the inability to speak, i.e. deaf-mutism. Works on the inability to speak whether from any functional or physical cause other than deafness are entered under Mutism.