Jargon: In infancy, long strings of unintelligible sounds with adultlike intonation that develop at about eight months of age and exhibit the pitch and intonational pattern of the language to which the child is exposed. Jargon may sound like questions, commands, and statements. In some aphasias, jargon refers to meaningless or irrelevant speech, characterized by typical intonational patterns and frequently correct syntax.
Jewett wave: The waveform resulting from auditory brain stem evoked response (ABER) audiometry, which measures amplitude and latency or time interval and enables an audiologist to identify the degree and type of hearing loss present and to establish a general site of a lesion.
Joule (J): The work obtained when a force of one Newton displaces an object one meter (one J is equal to 10 million ergs).
Jugular bulb: The bulbous protrusion of the jugular vein in the floor of the middle ear.
Kernahan's Striped Y: A visual classification system for cleft lip and palate.
Kernicterus: Deposits of bile pigment in the central nervous system, especially the basal ganglia. It is associated with erythroblastosis and the Rh factor.
Kinesics: The study of bodily movement and gesture. Also known as body language.
Kinetic energy: The energy of a mass that results from its motion.
Labiodental: Pertaining to lips and teeth; phonemes produced with lip and tooth contact.
Labyrinth: The system of interconnecting canals of the inner ear, composed of the bony labyrinth (filled with perilymph), that contains the membranous labyrinth (filled with endolymph).
Labyrinthitis: Inflammation of the labyrinth, resulting in hearing loss and vertigo.
Laddergram: The plotting of results on the ABLB test. The relative loudness at each ear is shown at several intensities at the test frequency.
Language impairment: A heterogeneous group of deficits and/or immaturities in the comprehension and/or production of spoken or written language.
Language sample: A systematic collection and analysis of a person's speech or writing. Sometimes called a corpus; used as a part of language assessment.
Language: A socially shared code for representing concepts through the use of arbitrary symbols and rule-governed combinations of those symbols.
Laryngeal cancer: Cancer of the larynx.
Laryngeal papillomas: Wartlike growths on the vocal folds.
Laryngeal prominence: The bulge produced by the thyroid cartilage of the larynx. Also known as the Adam's apple.
Laryngeal system: Structures of the larynx used for sound production.
Larynx: The superior termination of the trachea that protects the lower airways and is the primary sound source for speech production.
Late evoked responses (LERs): Those auditory evoked potentials evident after about 60 milliseconds. They are usually of larger amplitude than the earlier responses. Pure tones may be used as stimuli, and frequency-specific information may be available.
Latency: The time delay between the presentation of a stimulus and the measured physiological response to that stimulus.
Lateral cricoarytenoid muscle: Intrinsic laryngeal muscle that adduct the vocal folds.
Lateral lemniscus: That portion of the auditory pathway running from the cochlear nuclei to the inferior colliculus and medial geniculate body.
Lateral nasal processes: Primitive embryological tissue that gives rise to the nasal alae.
Lateral sulcus: The valley separating the frontal and temporal lobes of the brain. Also known as the fissure of Sylvius.
Lateral: Pertaining to the side. In phonology, it refers to the phoneme /l/, which is produced with air released on both sides of the tongue.
Lateralization: The impression that a sound introduced directly to the ears is heard in the right ear or the left ear.
Learning disability (LD): A heterogeneous group of disorders characterized by significant difficulties in the acquisition and use of listening, speaking, reading, writing, reasoning, or mathematical abilities thought to be due to central nervous system dysfunction.
Levatores costarum: Muscles on the posterior aspect of the vertebrae that can assist in inhalation.
Lexicon: Words of a language; also personal, internal dictionary.
Limited English proficiency (LEP): Language differences that are found in some individuals learning English as a second language. Differences do not in themselves constitute language impairments.
Lingua-alveolar: Pertaining to the tongue and alveolar ridge; phonemes produced with these in contact.
Linguadental: Pertaining to tongue and teeth; phonemes produced with tongue and tooth contact.
Linguapalatal: Pertaining to the tongue and hard palate; phonemes produced with the tongue in close proximity to the hard palate.
Linguavelar: Pertaining to the tongue and velum or soft palate; phonemes produced with the rear of the tongue approaching the velum.
Linguist: A speech scientist who studies the nature and structure of language(s) and often child language acquisition.
Linguistic intuition: A language user's underlying knowledge about the system of rules pertaining to his or her native language; linguistic competence.
Lipreading: See Speechreading.
Localization: The ability of an animal to determine the specific location of a sound source.
Logarithm: The exponent that tells the power to which a number is raised; the number of times that a number (the base) is multiplied by itself.
Lombard test: A test for nonorganic hearing loss based on the fact that speakers will increase the loudness of their speech when a loud noise interferes with their normal auditory monitoring.
Lombard voice reflex: The normal elevation of vocal intensity when the speaker listens to a loud noise.
Longitudinal wave: A wave in which the particles of the medium move along the same axis as the wave.
Loudness discomfort: level See Uncomfortable loudness level.
Loudness level: The intensity above the reference level for a 1000 Hz tone that is subjectively equal in loudness. The unit of measurement is the phon.
Loudness variations: Extreme, inappropriate variations in vocal intensity.
Loudness: The subjective impression of the power of a sound. The unit of measurement is the sone.
Lower motor neurons: Cranial and spinal nerves that innervate the muscles.
Lumbar vertebrae: Five individual vertebrae located immediately below the thoracic vertebrae.
Lungs: Organs that exchange oxygen and carbon dioxide during breathing and generate air pressure for speech production.
