Audiology Acronyms & Abbreviations

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A

• AAA — American Academy of Audiology; a U.S. professional organization for audiologists.
• AABR — Automated auditory brainstem response; commonly used in newborn hearing screening.
• AB — Advanced Bionics; a cochlear implant manufacturer.
• ABG — Air-bone gap; the difference between air-conduction and bone-conduction hearing thresholds. A significant air-bone gap can indicate a conductive component to hearing loss.
• ABI — Auditory brainstem implant; an implanted hearing device that stimulates the brainstem rather than the cochlea or auditory nerve.
• ABR — Auditory brainstem response; an electrophysiologic test used for newborn hearing screening, estimating hearing sensitivity, evaluating auditory neuropathy, and other diagnostic purposes.
• AC — Air conduction; hearing tested through headphones or insert earphones.
• AD — Auris dextra; right ear.
• ADA — Americans with Disabilities Act; U.S. civil-rights law that includes requirements related to accessibility for people with hearing loss.
• AGC — Automatic gain control; circuitry or software that automatically adjusts amplification based on incoming sound levels.
• AI — Can mean Articulation Index, an older measure of speech audibility, or artificial intelligence, particularly in discussions of modern hearing aids. Context matters.
• ALD — Assistive listening device; technology that helps a person hear in particular situations, such as a remote microphone or hearing loop system.
• ALS — Assistive listening system; a system designed to transmit sound more directly to people with hearing loss in places such as theaters, meeting rooms, and houses of worship.
• AN — May mean acoustic neuroma or auditory neuropathy. Because it is ambiguous, more specific terminology is preferable.
• ANL — Acceptable Noise Level; a test measuring how much background noise a person is willing to tolerate while listening to speech.
• ANSD — Auditory neuropathy spectrum disorder; a condition in which sound enters the inner ear but neural transmission of the signal is disrupted.
• ANSI — American National Standards Institute; publishes standards used for audiometers, hearing aids, hearing protection, and other equipment.
• APD / CAPD — Auditory processing disorder / central auditory processing disorder.
• APHAB — Abbreviated Profile of Hearing Aid Benefit; a questionnaire used to assess hearing difficulties and perceived hearing-aid benefit.
• ARHL — Age-related hearing loss; also called presbycusis.
• AS — Auris sinistra; left ear.
• ASHA — Usually the American Speech-Language-Hearing Association. In hearing-aid connectivity discussions, ASHA can also mean Google’s Audio Streaming for Hearing Aids protocol.
• ASL — American Sign Language.
• ASSR — Auditory steady-state response; an electrophysiologic test that can help estimate hearing thresholds.
• AU — Auris utraque; both ears.
• AuD — Doctor of Audiology.
• Auslan — Australian Sign Language.
• AzBio — AzBio Sentence Test; a speech-perception test commonly used during cochlear implant candidacy and outcome evaluations.

B

• BAHA / Baha — Bone-anchored hearing aid. Baha is also a Cochlear brand name, so generic terms such as BAHD or BCD may be preferable when discussing the technology broadly.
• BAHD — Bone-anchored hearing device.
• BC — Bone conduction; hearing tested by transmitting vibration through the skull rather than through the outer and middle ear.
• BCD / BCHD — Bone-conduction device / bone-conduction hearing device.
• BCI — Bone-conduction implant.
• BiCROS — Bilateral contralateral routing of signal; used when one ear is unaidable and the better ear also has hearing loss requiring amplification.
• BKB-SIN — Bamford-Kowal-Bench Speech-in-Noise Test; a clinical speech-in-noise test.
• BLE — Bluetooth Low Energy; a low-power version of Bluetooth used by many modern hearing devices.
• BPPV — Benign paroxysmal positional vertigo; a common inner-ear cause of brief episodes of positional vertigo.
• BSL — British Sign Language.
• BT — Bluetooth.
• BTE — Behind-the-ear hearing aid.

C

• CA — Cochlear Americas; cochlear implant and bone-conduction implant manufacturer.
• CAPD — Central auditory processing disorder. See APD.
• CBT — Cognitive behavioral therapy; a psychological treatment approach commonly used to help reduce tinnitus distress.
• CHL — Conductive hearing loss.
• CI — Cochlear implant.
• CIC — Completely-in-canal hearing aid.
• CMS — Centers for Medicare & Medicaid Services. In some state or local programs, CMS may alternatively mean Children’s Medical Services.
• CNC — Consonant-Nucleus-Consonant word test; commonly used to measure speech recognition, particularly in cochlear implant evaluations.
• COSI — Client Oriented Scale of Improvement; a questionnaire in which a person identifies specific listening situations they want hearing treatment to improve.
• CPT — Current Procedural Terminology; codes used in the U.S. to describe medical and audiologic procedures for billing and insurance purposes.
• CROS — Contralateral routing of signal; sends sound from an unaidable ear to the better-hearing ear.
• C-shell — Custom receiver-integrated earpiece or earmold used with a receiver-in-canal hearing aid. The term is especially associated with Phonak.
• CT — Computed tomography; medical imaging particularly useful for visualizing bone and anatomical structures.
• cVEMP — Cervical vestibular evoked myogenic potential; a vestibular test primarily evaluating the saccule and inferior vestibular nerve pathway.

D

• dB — Decibel; a logarithmic unit used to describe sound level.
• dBA / dB(A) — A-weighted decibels; a sound-level measurement weighted to approximate human sensitivity to different frequencies.
• dB HL — Decibels hearing level; the standardized scale typically used on an audiogram.
• dB SL — Decibels sensation level; a sound level expressed relative to an individual’s hearing threshold.
• dB SPL — Decibels sound pressure level; a physical measure of sound pressure.
• DHH / D/HH — Deaf and hard of hearing.
• DNN — Deep neural network; a type of machine-learning system increasingly used in hearing aids for tasks such as classifying sound environments or reducing background noise.
• DNR — Digital noise reduction; hearing-aid processing designed to reduce the prominence of certain background noises.
• DPOAE — Distortion-product otoacoustic emission; a type of OAE used to assess cochlear outer hair cell function.
• DSL — Desired Sensation Level; a hearing-aid fitting prescription commonly used in pediatric audiology.
• DSP — Digital signal processing; the electronic processing of sound inside a digital hearing aid or other audio device.
• DTC — Direct-to-consumer. A DTC hearing product is sold directly to the consumer but is not necessarily an FDA-regulated OTC hearing aid.

E

• EAA — Electroacoustic analysis; objective measurement of hearing-aid performance, generally using a hearing-aid test box.
• ECoG / ECochG — Electrocochleography; an electrophysiologic test that evaluates cochlear and auditory-nerve responses and may be used as part of an evaluation for conditions such as Ménière’s disease.
• ECV — Ear canal volume; commonly reported during tympanometry.
• EHDI — Early Hearing Detection and Intervention; U.S. programs focused on identifying and treating hearing loss in infants and young children.
• EM — Earmold.
• EMI — Can mean earmold impression in some clinics or electromagnetic interference in electronics and hearing-aid discussions.
• ENG — Electronystagmography; a method of recording eye movements during vestibular testing.
• ENT — Ear, nose, and throat physician; also called an otolaryngologist.
• ETD — Eustachian tube dysfunction.
• EVA — Enlarged vestibular aqueduct; an inner-ear malformation associated with hearing loss.

F

• FDA — U.S. Food and Drug Administration; regulates medical devices including prescription and OTC hearing aids.
• FM — Frequency modulation; traditionally refers to wireless remote-microphone systems used to improve the signal-to-noise ratio.
• FS — Full shell; generally referring to a full-shell earmold or hearing aid.
• FSA — Flexible Spending Account; a U.S. employee benefit account that may be used for eligible health expenses, including qualifying hearing-care expenses.

H

• HA — Hearing aid.
• HAT — Hearing assistive technology; broad term encompassing remote microphones, loops, alerting systems, streamers, and other accessibility technology.
• HCP — Hearing care professional/provider; broad term that can include audiologists, hearing instrument specialists, and other hearing-care professionals.
• HCPCS — Healthcare Common Procedure Coding System; U.S. medical billing codes that include codes for hearing-related products and services.
• HFA — High-frequency average; an average of hearing thresholds at selected higher frequencies. Exact frequencies may vary depending on context.
• HINT — Hearing in Noise Test; a clinical speech-in-noise test.
• HIS — Hearing Instrument Specialist.
• HL — Usually hearing loss in ordinary clinical or community shorthand. In dB HL, however, HL means hearing level.
• HHIE — Hearing Handicap Inventory for the Elderly; a questionnaire assessing the social and emotional effects of hearing difficulty.
• HHIA — Hearing Handicap Inventory for Adults; a related questionnaire designed for adults.
• HOH / HoH — Hard of hearing.
• HR — Human Resources.
• HSA — Health Savings Account.

I

• ICD — International Classification of Diseases; diagnostic codes used by healthcare professionals and insurers.
• IEC — International Electrotechnical Commission; develops international standards used for audiologic and electroacoustic equipment.
• IEP — Individualized Education Program; a U.S. educational plan for eligible students with disabilities, including some children with hearing loss.
• IFSP — Individualized Family Service Plan; a U.S. early-intervention plan generally used for eligible infants and toddlers.
• IIC — Invisible-in-canal hearing aid.
• IL — Intensity level.
• IMP — Impression; sometimes used as clinic shorthand for an earmold impression.
• IOI-HA — International Outcome Inventory for Hearing Aids; a short questionnaire used to assess hearing-aid outcomes.
• IP — Ingress Protection; a rating system describing resistance to intrusion by solids and water. For example, IP68 is commonly advertised for modern hearing aids.
• IR — Infrared; a wireless technology sometimes used in assistive listening systems.
• ITE — In-the-ear hearing aid.
• ITC — In-the-canal hearing aid.

L

• LC3 — Low Complexity Communication Codec; the audio codec used by Bluetooth LE Audio.
• LDL — Loudness discomfort level; the level at which sound becomes uncomfortably loud. Often used similarly to UCL.
• LE Audio — Bluetooth Low Energy Audio; newer Bluetooth audio technology used by some hearing aids, earbuds, phones, and assistive listening systems.

M

• MA — Medicare Advantage, also known as Medicare Part C.
• MCL — Most comfortable loudness level.
• MED-EL — Manufacturer of cochlear implants and other hearing implant systems.
• MEI — Middle ear implant.
• MFi — Made for iPhone; Apple’s technology and certification ecosystem used for direct communication between compatible hearing aids and Apple devices.
• MHL — Mixed hearing loss; hearing loss containing both conductive and sensorineural components.
• MIH — Microphone-in-helix; a custom hearing-aid configuration with a microphone positioned in the helix portion of the ear.
• MPO — Maximum power output; the maximum output level a hearing aid is allowed to produce.
• MRI — Magnetic resonance imaging; medical imaging particularly useful for soft tissue.

N

• NAL-NL2 — National Acoustic Laboratories Non-Linear 2; one of the most widely used hearing-aid fitting prescriptions.
• NFMI — Near-field magnetic induction; a short-range wireless technology that has been used for ear-to-ear communication between hearing aids.
• NIHL — Noise-induced hearing loss.
• NIOSH — National Institute for Occupational Safety and Health; U.S. agency that publishes workplace-health guidance, including recommendations related to hazardous noise exposure.
• NP — Nurse practitioner.
• NR — Noise reduction.
• NRR — Noise Reduction Rating; a U.S. laboratory-derived rating used on hearing-protection products such as earplugs and earmuffs.
• NU-6 — Northwestern University Auditory Test No. 6; a commonly used monosyllabic word list for measuring word recognition.
• NZSL — New Zealand Sign Language.

O

• OAE — Otoacoustic emission; a sound generated by the cochlea that can be measured in the ear canal to assess outer hair cell function.
• OID — Osseointegrated device; an implanted bone-conduction hearing system.
• OME — Otitis media with effusion; fluid in the middle ear without signs of acute infection.
• OSHA — Occupational Safety and Health Administration; U.S. agency responsible for workplace safety regulations, including occupational noise standards.
• OTE — Over-the-ear; sometimes used as an alternative description for a hearing aid worn behind the ear.
• OTC — Over-the-counter; in the U.S., a regulated category of hearing aids for adults age 18 and older with perceived mild-to-moderate hearing loss.
• oVEMP — Ocular vestibular evoked myogenic potential; a vestibular test primarily evaluating the utricle and superior vestibular nerve pathway.

P

• PA — Physician assistant / physician associate.
• PCP — Primary care physician/provider.
• PMM — Probe microphone measurement; objective measurement of hearing-aid output in a person’s ear. REM is the more familiar consumer-facing term.
• PRN — Pro re nata; as needed.
• PSAP — Personal sound amplification product; a consumer electronic product intended to amplify sounds for people without diagnosed hearing impairment. In the U.S., PSAPs are legally distinct from hearing aids.
• PTA — Pure-tone average, usually an average of selected audiometric thresholds. PTA may also be used informally to mean pure-tone audiometry.
• PTS — Permanent threshold shift; a lasting worsening of hearing thresholds, often discussed in relation to noise exposure.

Q

• QuickSIN — Quick Speech-in-Noise Test; measures the ability to understand speech in background noise and estimates SNR loss.

R

• REAR — Real-ear aided response; the sound-pressure level measured in the ear canal while a hearing aid is operating.
• RECD — Real-ear-to-coupler difference; a measurement used to translate hearing-aid test-box measurements to an individual’s ear.
• REIG — Real-ear insertion gain; the difference between aided and unaided sound levels in the ear canal.
• REM — Real-ear measurement; objective verification of hearing-aid amplification using a probe microphone placed near the eardrum.
• REOR — Real-ear occluded response; the sound level measured in the ear canal with the hearing device inserted but not actively amplifying.
• REUR — Real-ear unaided response; the natural sound-pressure response of the open ear without a hearing aid.
• RFC — Return for credit; commonly used when a hearing aid is returned to a manufacturer or supplier for credit.
• RIC — Receiver-in-canal hearing aid; the receiver/speaker sits in the ear canal and is connected by a thin wire to the hearing aid behind the ear.
• RIE — Receiver-in-ear; another term for the same basic hearing-aid design as RIC. Used particularly by some manufacturers.
• RITE — Receiver-in-the-ear; another term for the RIC/RIE hearing-aid style.
• RM — Remote microphone; a microphone placed near a talker that transmits their voice to hearing aids, cochlear implants, or another receiver.
• RTC — Return to clinic.

S

• SAT — Speech awareness threshold; the lowest level at which a person can detect speech. Often used similarly to SDT.
• SCD / SCDS — Semicircular canal dehiscence / superior canal dehiscence syndrome; an abnormal opening in the bone over a semicircular canal that can produce auditory and vestibular symptoms.
• SDT — Speech detection threshold; the lowest level at which speech can be detected without requiring recognition of the words.
• SII — Speech Intelligibility Index; an estimate of how much of the speech signal is audible.
• SIN — Speech in noise.
• SLP — Speech-language pathologist.
• SNHL — Sensorineural hearing loss.
• SNR — Signal-to-noise ratio; the relationship between the level of a desired signal, such as speech, and background noise.
• SNR loss — Signal-to-noise ratio loss; the additional SNR someone requires compared with a person with typical hearing to achieve similar speech understanding.
• SPL — Sound pressure level.
• SRT — Speech reception threshold; typically the lowest level at which a person can correctly repeat approximately 50% of presented spondee words.
• SSA — Social Security Administration.
• SSD — Single-sided deafness.
• SSNHL — Sudden sensorineural hearing loss; a rapid sensorineural hearing loss that warrants urgent medical evaluation.

T

• T / T-coil / TC — Telecoil; a small coil in some hearing aids and cochlear implant processors that can receive electromagnetic signals from hearing loops and compatible phones.
• TEOAE — Transient-evoked otoacoustic emission; another common type of OAE test.
• TFI — Tinnitus Functional Index; a questionnaire used to assess the impact and severity of tinnitus.
• THD — Total harmonic distortion; a measure of distortion sometimes included in electroacoustic hearing-aid testing.
• THI — Tinnitus Handicap Inventory; a questionnaire assessing the impact of tinnitus.
• TM — Tympanic membrane; the eardrum.
• TPA / 3PA — Third-party administrator; an organization that administers insurance or hearing-aid benefits on behalf of another organization.
• TRT — Tinnitus retraining therapy; a tinnitus-management approach combining counseling with sound therapy.
• TTS — Temporary threshold shift; a temporary worsening in hearing sensitivity following noise exposure.

U

• UCL — Uncomfortable loudness level; the sound level at which sound becomes uncomfortably loud. Also called LDL in many clinics.
• UHL — Unilateral hearing loss; hearing loss affecting one ear.
• UNHS — Universal Newborn Hearing Screening.

V

• VA — U.S. Department of Veterans Affairs. Often called the Veterans Administration conversationally.
• VEMP — Vestibular evoked myogenic potential; a family of tests used to evaluate parts of the vestibular system.
• vHIT — Video head impulse test; evaluates vestibulo-ocular reflex function of the semicircular canals.
• VNG — Videonystagmography; vestibular testing that records eye movements with video goggles.
• VR — Vocational Rehabilitation; U.S. state programs that may help eligible people obtain hearing technology or other support needed for employment.

W

• WDRC — Wide dynamic range compression; a fundamental hearing-aid processing strategy that applies more amplification to soft sounds than to loud sounds.
• WIN — Words-in-Noise Test; a clinical speech-in-noise test.
• WRS — Word recognition score; the percentage of test words correctly repeated at a specified presentation level.

Other common terms worth knowing

These aren’t necessarily acronyms, but they frequently appear alongside the abbreviations above:

• Audiogram — Graph showing hearing thresholds across different sound frequencies.
• Auracast — A Bluetooth LE Audio technology that allows compatible devices, including some hearing aids, to receive audio broadcasts in public or private spaces.
• Binaural — Relating to both ears.
• Bimodal — In hearing care, commonly describes using a cochlear implant in one ear and a hearing aid in the other.
• Closed dome — Hearing-aid earpiece with less venting than an open dome, generally providing more low-frequency amplification.
• Compression — Hearing-aid processing that reduces the range between soft and loud amplified sounds so they fit within the user’s usable hearing range.
• Dome — Small silicone earpiece commonly attached to the receiver or tubing of a hearing aid.
• Feedback — Whistling or squealing caused when amplified sound re-enters a hearing aid’s microphone.
• Feedback cancellation — Hearing-aid processing designed to detect and reduce acoustic feedback.
• Frequency lowering — Hearing-aid processing that moves high-frequency information into a lower-frequency region where it may be more audible.
• Gain — The amount of amplification a hearing aid provides.
• Hearing loop — Assistive listening system that transmits sound electromagnetically to a telecoil.
• Open fit — Hearing-aid fitting that leaves the ear canal relatively open, usually through an open dome or vented earmold.
• Presbycusis — Age-related hearing loss.
• Receiver — The miniature loudspeaker in a hearing aid.
• Remote microphone — External microphone that can be placed near a talker to improve their voice relative to surrounding noise.
• Speech mapping — Visual real-ear verification showing amplified speech in relation to hearing thresholds and prescribed targets.
• Streaming — Sending audio directly from a phone, television, computer, or other source to hearing devices.
• Tympanometry — Test of middle-ear function that measures how the eardrum responds to changes in air pressure.
• Vent — Opening through an earmold or custom hearing aid that allows air and sound to pass through the ear canal.
• Wax guard / wax filter — Replaceable filter designed to protect the hearing-aid receiver from earwax and debris.