NHPC BASLP key terms

The visible outer ear made of cartilage whose ridges and folds collect sound and help localize its source, especially in the vertical plane. It funnels energy toward the ear canal.

The tube running from the pinna to the eardrum, roughly 2.5 cm long in adults. It protects the middle ear and its resonance boosts high-frequency sound near 2–4 kHz.

A thin, cone-shaped membrane separating the outer and middle ear. Sound pressure moves it, and its vibration is transferred through the ossicles to the oval window.

The three middle-ear bones - malleus, incus, and stapes - that carry vibration from the eardrum to the oval window. They also amplify pressure through their lever action and area ratio.

The process by which the middle ear overcomes the mismatch between air-borne sound and the fluid-filled cochlea. Ossicular leverage and the tympanic-to-oval-window area ratio together produce about 25–30 dB of gain.

A channel connecting the middle ear to the nasopharynx that equalizes pressure across the eardrum. In children it is shorter and more horizontal, which raises the risk of middle-ear effusion.

The sensory structure resting on the basilar membrane inside the cochlea. It contains inner and outer hair cells whose stereocilia bend with membrane motion, generating the auditory nerve signal.

A membrane in the cochlea that varies in width and stiffness along its length. It is narrow and stiff at the base, responding to high frequencies, and wide and floppy at the apex, responding to low frequencies.

The pattern of vibration that moves from the base toward the apex of the cochlea when sound enters. Each frequency peaks at a specific place, forming the basis of place coding of pitch.

Cochlear cells that actively lengthen and shorten to sharpen and amplify the basilar membrane response. Damage to them, often from noise or ototoxic drugs, reduces sensitivity and frequency selectivity.

The orderly arrangement of frequency representation along the auditory pathway, from cochlea to auditory cortex. Neighboring neurons respond to neighboring frequencies, preserving a frequency map at each level.

The temporal-lobe region, chiefly Heschl's gyrus and surrounding areas, where sound is processed for pitch, timing, and pattern. It supports higher functions such as speech sound discrimination and auditory scene analysis.

The brain's capacity to reorganize its connections and representations with experience, learning, or injury. It underlies recovery after stroke and adaptation to hearing loss or a cochlear implant.

Twelve pairs of nerves emerging from the brainstem and brain that serve the head and neck. Several are essential to communication, including the trigeminal, facial, glossopharyngeal, vagus, accessory, and hypoglossal nerves.

The facial nerve, which supplies the muscles of facial expression and carries taste from the front of the tongue. It also innervates the stapedius muscle, so lesions can cause facial weakness and reduced acoustic reflex.

The vagus nerve, which provides motor supply to most muscles of the soft palate, pharynx, and larynx. Its recurrent laryngeal branch controls vocal fold movement, so damage causes hoarseness or aspiration risk.

A region in the posterior inferior frontal lobe of the dominant hemisphere associated with speech production and grammar. Damage produces nonfluent aphasia with effortful, telegraphic output but relatively preserved comprehension.

A region in the posterior superior temporal lobe of the dominant hemisphere linked to speech comprehension. Damage causes fluent aphasia with poor comprehension and often meaningless or jargon-filled output.

An acquired language disorder caused by brain damage, typically stroke, affecting comprehension, production, reading, or writing while cognition is broadly preserved. It is classified by fluency, repetition, and comprehension patterns.

The number of cycles of a sound wave per second, measured in hertz (Hz). It corresponds roughly to perceived pitch, and human hearing spans about 20 Hz to 20,000 Hz.

The tendency of a cavity or object to vibrate strongly at particular frequencies. Vocal tract resonances shape speech sounds, and ear canal resonance boosts hearing sensitivity in the high frequencies.

A peak in the acoustic spectrum of a speech sound produced by vocal tract resonance. Vowel identity depends largely on the first two formants, and formant transitions cue consonant place of articulation.

A visual display plotting frequency on the vertical axis against time on the horizontal axis, with darkness showing energy. It reveals formants, noise bursts, and voice onset time used to analyze speech.

The perceptual attribute of sound ordered from low to high, closely related to frequency but not identical to it. It also depends on intensity and waveform, and is measured experimentally through matching tasks.

The subjective perception of sound intensity, which depends on frequency as well as sound pressure level. Equal-loudness contours show that mid-frequency sounds seem louder than very low or very high ones at the same level.

A logarithmic unit expressing the ratio between two sound quantities. In audiology, dB HL references normal hearing thresholds, dB SPL references physical pressure, and dB SL references a listener's own threshold.

The smallest change in a stimulus, such as frequency or intensity, that a listener can reliably detect. It quantifies discrimination ability and underlies tests of frequency and intensity resolution.

The standard behavioral test measuring hearing threshold across frequencies using tones delivered by earphones or bone vibrator. Results are plotted on an audiogram and define degree, type, and configuration of hearing loss.

A graph of hearing threshold in dB HL across frequencies from about 125 to 8000 Hz. Standard symbols distinguish right and left ears and air versus bone conduction, revealing the type of loss.

The average of air-conduction thresholds at selected frequencies, commonly 500, 1000, and 2000 Hz. It summarizes overall hearing level and is often used to classify degree of loss.

The difference between air-conduction and bone-conduction thresholds at the same frequency. A gap indicates a conductive component, while absent gap with elevated bone thresholds indicates sensorineural loss.

Low-level sounds generated by outer hair cell activity that can be recorded in the ear canal. Their presence suggests healthy cochlear function, making them useful for newborn screening and detecting auditory neuropathy.

An evoked potential recorded from scalp electrodes within about 10 ms of a click or tone burst. Its waves reflect auditory nerve and brainstem activity and estimate hearing thresholds objectively, including in infants.

Contraction of the stapedius muscle in response to loud sound, stiffening the middle ear and reducing transmission. Its threshold and decay patterns help assess middle-ear and retrocochlear function.

The lowest hearing level at which a listener correctly repeats about 50 percent of familiar spondaic words. It cross-checks pure tone thresholds and confirms the reliability of the audiogram.

The percentage of words or phonemes correctly identified at a specified presentation level, usually above threshold. It indicates how well speech is understood once audible and helps guide rehabilitation planning.

The process of selecting, programming, and verifying amplification to match a person's hearing loss and communication needs. It includes real-ear measurement and outcome evaluation rather than prescription alone.

Probe-microphone recording of the sound level actually reaching the eardrum while a hearing aid operates. It verifies that prescribed gain targets are met, accounting for individual ear canal acoustics.

A device that converts sound into electrical pulses delivered to electrodes in the cochlea, bypassing damaged hair cells. It requires auditory training and mapping, and outcomes vary with age at implantation and duration of deafness.

Structured practice in detecting, discriminating, and identifying sounds to improve listening skills. It is used with hearing aids and cochlear implants and for central auditory processing difficulties.

Fluid accumulation in the middle ear without signs of acute infection, common in young children. It causes conductive hearing loss and can delay speech and language if persistent and bilateral.

The interval between the release of a stop consonant and the start of vocal fold vibration. It distinguishes voiced from voiceless stops and is a key acoustic measure in speech assessment.

Systematic transcription and measurement of a child's spontaneous speech, yielding mean length of utterance, vocabulary diversity, and grammatical accuracy. It complements standardized tests with naturalistic evidence.

The average number of morphemes per utterance in a language sample, commonly abbreviated MLU. It is a widely used index of grammatical development in young children.

A test-teach-retest approach that measures how much a learner improves with structured support. It distinguishes language difference from disorder and estimates learning potential rather than prior knowledge alone.

A motor speech disorder from damage to the nervous system, affecting strength, speed, range, or coordination of speech movements. Speech is often slurred or slow, and treatment targets intelligibility and efficiency.

A motor planning disorder in which the person has difficulty programming the movements for speech despite intact muscles. Errors are inconsistent, with groping and distorted substitutions, and treatment emphasizes repetitive practice.

The degree to which a listener understands a speaker's intended message. It is a primary outcome of speech intervention and is measured by transcription accuracy or listener rating scales.

Methods and devices that supplement or replace natural speech for people with severe communication impairment. Systems range from picture boards to speech-generating devices and are selected to match participation needs.

A client's voluntary agreement to assessment or treatment after receiving understandable information about purpose, risks, benefits, and alternatives. It respects autonomy and must be documented and revisable.

The professional duty to protect client information from unauthorized disclosure. Exceptions include suspected abuse, serious risk of harm, and legal requirements, and records must be stored and shared securely.

The range of services a professional is trained and legally permitted to provide. It guides referral and collaboration, and practicing outside it can harm clients and lead to disciplinary action.

Clinical decision-making that integrates the best available research, clinician expertise, and client values and preferences. It requires appraising evidence quality and applying it to the individual case.

A study in which participants are randomly assigned to intervention or comparison groups. Randomization reduces selection bias and supports causal conclusions about treatment effect.

A standardized measure of the magnitude of a difference or association, independent of sample size. It indicates clinical importance, unlike a p-value that only addresses statistical significance.

A range of values likely to contain the true population parameter, usually at 95 percent confidence. Its width reflects precision, and intervals crossing zero suggest no reliable effect.