TDD: Telecommunication device for the deaf. Also referred to as a TTY (tele-typewriter). A special device that allows for the transmission of and reception of words over phone lines via a typewritten signal.


Telecoil: A coil placed inside of a hearing aid that picks up electro-magnetic energy emitted by certain telephones and assistive listening devices.


Threshold Of Hearing: The lowest level that a particular sound's presence can be perceived by an individual more than half of the time.


Tinnitus: The perception of the presence of a sound in one or both ears that is not associated with an external sound source. Tinnitus can be described as constant or intermittent and of various volume levels, pitches, and complexities (ringing, roaring, hissing, crickets, whistling, rushing, etc.).


Transmitter: The portion of a CROS system that picks up a signal on one side of the head and sends it via a hard wire or an FM signal to the receiver on the other side of the head.


TTS (Temporary Threshold Shift): The presence of some degree of hearing loss, often induced by noise or chemical exposure, that recovers over time.


Tympanic Membrane: Another name for an eardrum. It is the membrane that separates the ear canal and the middle ear cavity. The tympanic membrane vibrates when hit with sound waves, causing the ossicular chain to vibrate.


Tympanogram: A chart onto which the compliance results of tympanometry are graphed. 


Tympanometry: A test, also referred to as immittance testing, done during an audiological evaluation that helps to assess the integrity of the tympanic membrane (eardrum) and the middle ear cavity. During tympanometry testing, a probe is inserted into and sealed in the ear canal and then a reflected tone is measured as the pressure in the ear canal is changed. The results are often graphed onto a tympanogram, showing the compliance at various positive and negative pressure levels.


Uncomfortable Loudness Level (UCL): A measurement that is often made prior to the ordering of or programming of a hearing aid that determines, for speech or tones, the intensity level at which a patient judges a particular signal to be uncomfortably loud.


Unilateral: Pertaining to only one ear or one side of the head (i.e., The person with a hearing loss on the right but not the left has a unilateral hearing loss.).


Vent: A hole placed in a hearing aid or earmold to modify the amount of occlusion effect noted by a hearing aid wearer or to adjust the frequency response of the hearing aid.


Vertigo: A sensation of spinning experienced by individuals with vestibular problems.


Vestibular System: The inner ear portion of the balance system.


Vestibulocochlear Nerve: Another name for the auditory nerve or the VIIIth cranial nerve which connects the cochlea to the brainstem and is made up of both auditory and vestibular nerve fibers.


Visual Reinforcement Audiometry: A procedure used when testing the hearing of very young patients. The young patient is trained to associate a sound with an interesting visual experience (such as a flashing light or an animated stuffed animal) so that future presentations of audible sounds elicit head movements.


Volume Control: A wheel or button on the faceplate of a hearing aid or on a remote control utilized by a hearing aid wearer to increase or decrease the instrument's gain.


Wax Loop: A small tool used by professionals and hearing aid users to clean ear wax out of the tubing of a hearing aid.


WNL: Within normal limits.


Word Recognition Score: The percentage of a list of speech stimuli that an individual is able to repeat.