Acoustic Neurinoma - tumor, usually benign, which may develop on the hearing and balance nerves and can cause gradual hearing loss, tinnitus, and/or dizziness. (sometimes called vestibular schwannoma). Also see Neurofibromatosis Type 2.

Acquired Deafness - loss of hearing that occurs or develops some time during the lifespan but is not present at birth.

American Sign Language (ASL) - manual language with its own syntax and grammar, used primarily by people who are deaf.

Amplifier - An integral part of a hearing aid or other Assistive Listening Device. Sound waves are transmitted to the amplifier via electrical impulse, where they are reconverted to sound. Digital amplifiers will analyze and process the sound waves to provide an enhanced listening experience.

Amplitude - refers to the height of a sound wave.

Ampulla: This term is used in many medical contexts, but in this instance refers to the ear's semicircular canals.

Analog Hearing Aids - Analog hearing aids capture sound in a microphone, convert them to electrical impulses, and then reconvert them to sound in an amplifier, making them louder for the user.

Aphasia - total or partial loss of the ability to use or understand language; usually caused by stroke, brain disease, or injury.

Aphonia - complete loss of voice.

Articulation Disorder - inability to correctly produce speech sounds (phonemes) because of imprecise placement, timing, pressure, speed, or flow of movement of the lips, tongue, or throat.

Assistive Devices - technical tools and devices such as alphabet boards, text telephones, or text-to-speech conversion software used to aid individuals who have communication disorders perform actions, tasks, and activities.

Assistive Listening Device: ALDs are instruments designed to transmit amplified sound to the user. They use a variety of methods, including cords, radiowaves, inductive loops and infrared. Corded systems are generally used to assist in communication between two people. With radio wave devices, the speaker wears a transmitter and the listener wears an amplifier. These are frequently used in classrooms. Inductive loop systems are built into a large room, such as a church sanctuary, or a concert hall. Users with telecoils are able to pick up the signals. Infrared systems transmit sound from the speaker to the listener using infrared. A drawback of this is that it requires line of sight to the transmitter.