Malingering: The faking of a hearing loss for social or financial reasons.


Malleus: The first / hammer-shaped bone in the ossicular chain, that is attached to the eardrum.


Masking Noise: A sound introduced into an ear system for the purpose of covering up an unwanted sound. Masking noises are used during hearing tests to cover-up unwanted responses from a non-test ear. Tinnitus maskers also utilize a masking noise to cover-up tinnitus.


Mastoid Bone: A portion of the temporal bone that is located behind the external ear. The bone conduction vibrator employed during bone conduction testing is usually placed on the mastoid.


Medical Clearance: A statement from a physician required before the dispensing of a hearing aid, unless a waiver is signed by the patient, that states that there are no medical contraindications to the use of a hearing aid.


Meniere's Disease: A disorder with a set of symptoms (usually including vertigo, hearing loss, and tinnitus) that results from an over-production of fluid in the endolymphatic sac of the inner ear (hydrops).


Microphone: The entry point for sound into a hearing aid. The mechanism inside a hearing aid that converts sound waves into an electrical signal.


Microtia: A condition in which an individual is born with an abnormally small pinna.


Middle Ear: The portion of the human auditory system located between the outer and inner ear, which uses the tympanic membrane (eardrum) and ossicles (malleus, incus, and stapes) to transfer the sound via motion (mechanical energy) from the ear canal to the cochlea.


Middle Ear Effusion: When the body discharges fluid into the middle ear cavity.


Mixed Hearing Loss: A hearing loss that has both conductive and sensori-neural components.


Monaural: Sound is presented only to one ear (i.e., A monaural hearing aid fitting involves only one ear.).


Most Comfortable Level (MCL): 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 that a patient considers to be the most acceptable in regards to the overall comfort of the signal.


Multi-Band Hearing Aid: A programmable hearing aid that allows the dispenser to adjust gain in a specified set of frequencies without effecting gain at other frequencies.


Multi-Channel Hearing Aid: A programmable hearing aid that allows the dispenser to adjust the instrument's compression characteristics in a specified set of frequencies without effecting the compression characteristics at other frequencies.


Multi-Memory Hearing Aid: A hearing aid that has more than one dispenser adjusted listening program that the patient can access to improve communication in various environments (i.e., memory one for normal listening, memory two for noisy environments, and memory three for telephone use).


Noise-Induced Hearing Loss: A type of hearing loss caused by the introduction of intense volumes into a human ear system over long periods of time or very intense volumes for a short period of time. The hearing loss often is worse on the side of exposure and is most pronounced in the higher frequencies.


Nonorganic Hearing Loss: Symptoms of hearing loss that are not associated with an obvious physical dysfunction of the auditory system.


Nystagmus: Physical movement of the eyeballs that occurs in a rhythmic nature when the vestibular system is over-stimulated or spontaneously in certain abnormal vestibular systems.


Occlusion: In regards to hearing aids, the sensation that results from "plugging up" the ear canal with cerumen, an un-vented hearing aid, or a foreign body.


Occupational Hearing Loss: The hearing loss associated with the exposure to loud sounds in a work environment.


On-The-Ear (OTE) Or Open Ear Hearing Aid: A more recently developed style of a BTE hearing aid that utilizes a thinner tubing and a placement of the electronics lower down behind the ear for better cosmetic appeal with less occlusion.


Organ Of Corti: The structure built upon the basilar membrane inside of the spiral cochlea that contains the special sensory receptors (hair cells).


Ossicular Chain: The three smallest bones in the body, located in the middle ear.  They are connected together to form a link between the tympanic membrane (eardrum) and the cochlea. The three ossicles, called the malleus, incus and stapes (hammer, anvil, and stirrup), transfer the sound through the middle ear via vibrations.


Oscillation: Feedback. The whistling that hearing aids can emit when an amplifier becomes unstable.


Oscillator: A device that is used to produce vibrations, such as the bone conduction oscillator used during bone conduction threshold testing.


Otalgia: Ear pain or earache.


Otitis Media: Inflammation and/or infection of the middle ear.


Otoacoustic Emissions (OAEs): A test sometimes performed during an audiological evaluation or screening that measures the outer hair cell function in the cochlea.


Otoblock: A sponge or piece of cotton that usually has a string attached to it, used by a hearing healthcare professional during the impression taking procedure necessary to the ordering of a custom fit hearing aid, to prevent the impression material from going too deep into the ear canal.


Otolaryngologist: An Ear, Nose, and Throat (ENT) physician.


Otologist: An ENT physician who specializes in the evaluation and treatment of the ear.


Otorrhea: Drainage from the ear often caused by an external ear infection or a middle ear problem with a tympanic membrane (eardrum) perforation.


Otoscope: A magnifying and lighting tool utilized by health care workers to look into the ear canal.


Otoscopic Examination: The use by a healthcare professional of the lighted and magnified vision provided by an otoscope to evaluate the integrity of the pinna, ear canal and eardrum.


Otosclerosis: An abnormal condition of the middle ear in which there is a formation of spongy bone onto the footplate of the stapes, resulting in a conductive hearing loss.


Ototoxic Medications: Prescription, over-the-counter drugs, or herbal remedies that can have a temporary or permanent detrimental effect on an individual's hearing or balance system.


Outer Ear: The most peripheral aspect of the human auditory system that includes the auricle (pinna) and external auditory meatus (ear canal).


Output Limiting: The various parameters designed into a hearing aid by a manufacturer that controls the upper limits of total volume (input + gain) that a hearing aid can produce.


Oval Window: A connection between the stapes footplate of the middle ear and the fluid filled inner ear through which sound vibrations pass in a normal auditory system.