Habitual pitch: The basic frequency level that an individual uses most of the time.
Hair cells: Auditory receptor cells found on the basilar membrane that are responsible for encoding the auditory information for the brain.
Hard glottal attacks: Abrupt initiation of voicing using hypertensive vocal fold adduction.
Hard of hearing: Mild to moderately severe hearing loss. Hard-of-hearing individuals usually depend as much as possible on their hearing for communication and learning of new concepts.
Hard swallow: A technique in which the patient attempts to swallow forcefully to trigger pharyngeal swallow.
Harmonic distortion: The distortion created when harmonic frequencies are generated in an amplification system; usually expressed in percentage of distortion.
Harmonic: Any whole-number multiple of the fundamental frequency of a complex wave. The fundamental frequency equals the first harmonic.
Harmonics: Frequencies in a complex sound that are integer multiples of the fundamental frequency.
Head rotation: A posture with the head turned toward the impairment, used for some clients with a swallowing disability.
Head tilt position: A posture with the head away from the impairment, used for some individuals with a swallowing disability.
Head-back position: A posture with the head held back that is useful for some clients with a swallowing disability.
Hearing Aid Industry Conference (HAIC): An organization of hearing-aid manufacturers that provides standardization of measurement and reporting on hearing-aid performance data.
Hearing disability: An inability to perform socially useful functions due to hearing loss. A given disability may or may not present a handicap.
Hearing disorder: Impaired sensitivity of the auditory system.
Hearing handicap: The ways in which a hearing loss has a frustrating effect on individual roles or goals.
Hearing impairment: Abnormality of structure or function that is physiological, psychological, or anatomical.
Hearing level (HL): The number of decibels above an average normal threshold for a given signal. The hearing-level dial of an audiometer is calibrated in dB HL.
Hearing loss: Any loss of sound sensitivity, partial or complete, produced by an abnormality anywhere in the auditory system.
Hearing therapy: An instruction, usually offered in groups, to enhance recognition of, and intervention for, those variables within the environment, or poor speaker or listener habits, that impede successful communication.
Helicotrema: A passage at the apical end of the cochlea connecting the scala vestibuli with the scala tympani.
Hematoma: Blood trapped in an organ or skin tissue owing to injury or surgery.
Hemiparesis: Muscle weakness on one side of the body, resulting in reduced strength and control.
Hemiplegia: Paralysis on one side of the body.
Hemisensory impairment: Loss of the ability to perceive sensory information on one side of the body.
Hemorrhagic stroke: A type of stroke resulting from the weakening of arterial walls that burst under pressure.
Hemotympanum: Bleeding in the middle ear.
Hereditodegenerative hearing loss: A hearing loss of genetic origin, with onset after birth.
Hereditodegenerative hearing loss: Hearing loss that has its onset after birth but is nonetheless hereditary.
Hertz (Hz): Cycles per second (cps).
Heschl's gyrus: An area in each cerebral hemisphere that receives all incoming auditory stimuli and separates it into linguistic and para-linguistic information.
Hesitation: A pause before or between parts of utterances. If used excessively, it may be considered a sign of dysfluency or stuttering.
Heterozygous: Possessing different genes at a specific site between paired chromosomes.
High-frequency average (HFA): An ANSI hearing-aid specification expressed as the average SPL at 1000, 1600, and 2500 Hz.
High-risk registry: A set of criteria designed to help identify neonates whose probability of hearing loss is greater than normal.
HIV/AIDS: See Human immunodeficiency virus/acquired immunodeficiency syndrome.
Hoarseness: A voice quality that is characterized by a rough, usually low-pitched quality.
Holistic: Pertaining to the whole; multidimensional.
Homozygous: Possessing identical genes at a specific site between paired chromosomes.
Human immunodeficiency virus (HIV): A virus transmitted through body fluids that first appeared in the United States in the early 1980s. The virus affects the immune system and creates the possibilities of conductive, sensory, and neural hearing loss.
Huntington's chorea: An inherited progressive disease also known as Huntington's disease, resulting from a genetic defect on chromosome 4.
Hyoid bone: Free floating bone above the larynx that anchors tongue and laryngeal muscles.
Hypacusis: Loss of hearing sensitivity.
Hyperacusis: A collapse of loudness tolerance with or without accompanying hearing loss.
Hyperadduction: Excessive movement toward the midline, often resulting in a tense voice quality.
Hyperfluent speech: Very rapid speech found in people with fluent aphasia and characterized by few pauses, incoherence, inefficiency, and pragmatic inappropriateness.
Hyperkinetic dysarthria: A speech disorder characterized by increased movement, such as tremors and tics, and by inaccurate articulation.
Hyperlexia: A mild form of pervasive developmental disorder (PDD) characterized by an inordinate interest in letters and words and by early ability to read but with little comprehension.
Hyperrecruitment: A condition of some pathological hearing disorders in which a tone of a given intensity produces a sensation of greater loudness than that same intensity would produce for a normal ear.
Hypertonia: A condition in which there is too much muscle tone, especially in those muscles that oppose the bending of joints and that help us to stand erect. Also called spasticity.
Hypoadduction: Reduced movement toward the midline of the vocal folds, often resulting in a breathy voice quality.
Hypokinesia: Abnormally decreased motor function or activity.
Hypokinetic dysarthria: A speech disorder that is characterized by a decrease or lack of appropriate movement as muscles become rigid and stiff, resulting in monopitch and monoloudness and imprecise articulation.
Hyponasality: A lack of nasal resonance.
Hypotonia: Poor muscle tone and weakness.
Hysterical deafness: An older term for psychogenic hearing loss.
Immittance bridge (tympanometer): A hand-held probe that is used in audiometric testing of the mobility of the eardrum as the air pressure in the canal is systematically modified. From the recorded data, the tympanometer generates a graph, or tympanogram, comparing changes in air pressure to compliance of the eardrum.
Immittance testing: A procedure for assessing mobility of the eardrum in the differential diagnosis of conductive pathology.
Immittance: A term used to describe measurements made in the plane of the tympanic membrane.
Impedance: The opposition to sound-wave transmission. It comprises frictional resistance, mass, and stiffness and is influenced by frequency.
Implicit: Assumed but not directly expressed.
Inappropriate pitch: Pitch judged to be outside the normal range of pitch for age and/or sex.
Inaudible prolongations: Stuttering behavior characterized by a silent break before or within a word, such as "-girl."
Incidence: The number of new cases of a disorder at a particular point in time in a designated population.
Incidental teaching: Using a natural activity to train targets.
Incomplete cleft: A separation of a normally fused structure that involves only a portion of the structure.
Incus: The second bone in the ossicular chain, connecting the malleus to the stapes. It is named for its resemblance to an anvil.
Individualized Educational Plan (IEP): An annually updated, federally mandated plan for the education of children with handicaps.
Individualized Family Service Plan (IFSP): An annually updated, federally mandated plan for early intervention services for infants and toddlers with special needs and their families.
Inertial bone conduction: Stimulation of the cochlea caused by lag of the chain of middle-ear bones, or inner-ear fluids, when the skull is deformed, resulting in movement of the stapes in and out of the oval window.
Infarction: Death of bodily tissue due to deprivation of the blood supply.
Inferior colliculus: One of the central auditory pathways, found in the posterior portion of the midbrain.
Inferior longitudinal muscle (tongue): Intrinsic muscle of the tongue that shortens the tongue.
Initial masking (IM)
The lowest level of effective masking presented to the nontest ear. For air-conduction tests, this level is equal to the threshold of the masked ear; for bone-conduction tests the IM is equal to the air-conduction threshold of the masked ear plus the occlusion effect at that frequency.
Inner ear: The interior section of the ear containing the cochlea. It supplies information regarding balance, spatial orientation, and hearing by converting mechanical energy to electrochemical energy for transmission to the brain.
Insertion gain: The decibel difference between unaided and aided conditions as measured through a probe-tube microphone system. Commonly referred to as Real Ear Insertion Gain (REIG).
Insertion loss: The additional loss of hearing created by placing a hearing aid, turned off, within the ear.
Insular: Related to the insula, the central lobe of the cerebral hemisphere.
Integrated circuit: An inseparable unification of several transistors and resistors on a small piece of silicon maintaining an electrical isolation of the circuit components.
Intelligibility: The ease with which an individual's speech is understood.
Intensity level (IL): An expression of the power of a sound per unit of area. The reference level in decibels is 10-l2 watt/m2, or 10-l6 watt/cm2.
Intensity: A measure of loudness generally expressed in decibels.
Intentionality: Goal directedness in interactions. It is first demonstrated at about eight months of age primarily through gestures.
Interarytenoid muscle: Intrinsic laryngeal muscle that adducts the vocal folds.
Interaural attenuation (IA): The loss of energy of a sound presented by either air conduction or bone conduction as it travels from the test ear to the nontest ear; the number of decibels lost in cross-hearing.
Interdental: Between the teeth; see Linguadental.
Internal auditory canal: A channel from the inner ear to the brainstem allowing passage of the auditory and vestibular branches of the VIIIth nerve, the VIIth nerve, and the internal auditory artery.
Internal error sound discrimination: Judging the accuracy of one's own phoneme production; intrapersonal error sound discrimination.
Internal intercostal muscles: Eleven pairs of muscles between the ribs that assist in exhalation.
Internal oblique muscle: Abdominal muscle that can contribute to forced exhalation.
Interpersonal error sound discrimination: See External error sound discrimination.
Intonation: Pitch movement within an utterance.
Intra-aural muscle reflex: The contraction of the stapedius muscles produced by introduction of an intense sound to one ear. The reflex is a bilateral phenomenon.
Intra-axial: Inside the brainstem.
Intraoperative monitoring: The use of auditory evoked potentials, such as ECoG and ABR for monitoring some of the electrophysiological states of the patient during neurosurgery.
Intrapersonal error sound discrimination: See Internal error sound discrimination.
Intrinsic muscles (laryngeal): Muscles that have both points of attachment on the larynx.
Inverse square law: The intensity of a sound decreases as a function of the square of the distance from the source.
Ischemic strokes: A cerebrovascular accident resulting from a complete or partial blockage or occlusion of the arteries transporting blood to the brain.
