BC-HIS flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Decibel definition (dB SPL)

A logarithmic ratio of a measured sound pressure to a reference of 20 micropascals, calculated as 20 times the base-10 logarithm of that pressure ratio.

Inverse square law

In a free field, doubling the distance from a point source reduces sound intensity by 6 dB because energy spreads over four times the area.

Wavelength formula

Wavelength in meters equals the speed of sound (about 343 m/s) divided by frequency in hertz, so higher frequencies have shorter wavelengths.

dB HL reference

A hearing level scale referenced to normative human thresholds per ANSI S3.6, so 0 dB HL equals different SPL values at different frequencies.

Resonance

A condition in which a system driven at its natural frequency vibrates with maximum amplitude, amplifying energy near that frequency.

Speech spectrum peak

Vowel energy concentrates near 500 Hz, while consonant energy, critical for intelligibility, is concentrated above 2000 Hz.

Middle ear impedance matching

The tympanic membrane area to stapes footplate area ratio plus ossicular lever action produce roughly 25-30 dB of pressure gain.

Acoustic reflex arc

Loud sound triggers stapedius contraction via the facial nerve (CN VII), stiffening the ossicular chain and reducing low-frequency transmission.

Cochlear tonotopy

The base of the cochlea responds to high frequencies and the apex to low frequencies, creating a place-code map of frequency along the basilar membrane.

Outer hair cell function

Outer hair cells provide active cochlear amplification, sharpening frequency tuning and generating otoacoustic emissions detectable in the ear canal.

Inner hair cell role

Inner hair cells are the primary sensory receptors, synapsing with most type I auditory nerve fibers that carry signals to the brainstem.

Endocochlear potential

The stria vascularis maintains a positive potential of about +80 mV in the scala media relative to perilymph, driving hair cell transduction.

Auditory nerve pathway

CN VIII exits via the internal auditory meatus and synapses first at the ipsilateral cochlear nucleus before crossing to higher brainstem centers.

Air-bone gap

A difference of more than 10 dB between air-conduction and bone-conduction thresholds, indicating a conductive component to hearing loss.

Pure-tone average

The arithmetic mean of air-conduction thresholds at 500, 1000, and 2000 Hz, commonly used to classify degree of hearing loss.

Type B tympanogram

A flat tympanogram with no distinct pressure peak, suggesting middle ear effusion, perforation, or cerumen occluding the probe.

Presbycusis presentation

Age-related hearing loss typically appears as bilateral, symmetric, high-frequency sensorineural loss with reduced speech recognition in background noise.

OSPL90

The saturation output level measured with a 90 dB SPL input, representing maximum hearing aid output and compared against uncomfortable loudness levels.

Harmonic distortion limits

ANSI S3.22 requires total harmonic distortion below 3 percent at 500 and 800 Hz and below 5 percent at 1600 Hz.

Compression ratio

The ratio of input level change to output level change above the compression knee point; higher ratios produce more gain reduction.

Equivalent input noise

The internal noise of a hearing aid referred to its input; values below roughly 30 dB SPL are considered acceptable.

Feedback loop gain

Feedback occurs when amplified sound leaks back to the microphone and loop gain reaches unity, causing oscillation at specific frequencies.

Directional microphone benefit

Directional microphones attenuate sounds from behind, improving the signal-to-noise ratio by roughly 3-5 dB in diffuse noise.

Real-ear aided response

The ear canal SPL measured with the hearing aid on and a speech-like signal, compared against prescriptive targets during verification.

Real-ear insertion gain

The difference between aided and unaided ear canal SPL at each frequency, representing the gain actually delivered to the eardrum.

Speech intelligibility index

A 0-to-1 scale estimating the proportion of speech information audible through the aided response, used to quantify fitting adequacy.

RECD purpose

The real-ear-to-coupler difference converts coupler-based measures to ear canal values, essential for accurate pediatric prescriptive fitting.

Occlusion effect

Amplified low-frequency bone-conducted sound trapped in an occluded ear canal, producing a boomy sensation below 500 Hz.

FDA adult waiver

Adults may sign a waiver declining medical evaluation before hearing aid fitting; patients under 18 require physician evaluation first.

FTC 30-day return

The FTC Hearing Aid Rule requires a receipt stating a 30-day return policy and providing a user instructional brochure.

Binaural fitting rationale

Fitting both ears for bilateral loss improves localization, speech in noise, and loudness comfort, and is standard unless contraindicated.

HIPAA relevance

Audiologic records contain protected health information subject to HIPAA privacy and security safeguards, including secure storage and transmission.