See OtoAcoustic Emissions.

Involuntary, rapid, rhythmic, back-and-forth movement of the eyes that may accompany vertigo. This is typically caused by damage to the vestibular system, or to the central nervous system.

See Noise Reduction Rating.

A person who writes notes for a hard of hearing or deaf person in various settings such as the classroom, meetings, or at the office.

Hearing ranging between -10 decibels (dB) and 15 dB.

Hearing aids that amplify soft sounds by a different amount than loud sounds in order to keep the volume comfortable to the wearer. Digital hearing aids are almost always programmed to be non-linear.