A two-to-one relationship between frequencies. Thus 1000 Hz is one octave above 500 Hz.

See Otitis Media with Effusion.

This is the traditional microphone that is built into hearing aids. It picks up sounds from all directions.

Hearing aids that use open fit ear molds. These ear molds fit loosely in the ear canal and thus permit natural sounds to enter and the louder low frequency sounds from the hearing aid to escape thus preventing the distorted and muffled occlusion effect.

A digital hearing aid that can be set for different hearing losses and also has he potential to be reprogrammed to code or filter speech in ways that may not even have been invented yet.

An approach based on the principle that most hard of hearing and deaf people can be taught to listen and speak with early intervention and consistent training to develop their hearing potential. The goal is for these children to grow up to become independent, participating citizens in mainstream society. Also known as Auditory-Oral Education.