MGT of hearing disorders: Audiometry

100 vocabulary flashcards covering key concepts, terms, and procedures from the audiometry lecture notes.

Audiometry

The measurement of hearing ability using controlled auditory stimuli to determine thresholds across frequencies.

Sine waves

Pure-tone stimuli that represent a single frequency used in audiometry.

Pure tones

Single-frequency sounds used to measure hearing thresholds.

dB SPL

Decibels Sound Pressure Level; a physical reference for sound intensity; sensitivity varies with frequency.

0 dB SPL reference

The reference level for dB SPL; 0 dB does not mean no sound.

Minimum Audibility Curve

The curve showing the softest sounds audible to humans across frequencies.

dB HL

Decibels Hearing Level; a norm-referenced scale based on normal-hearing thresholds.

Normal thresholds

Hearing thresholds within about 0–25 dB HL.

Audiometer

Instrument that generates sounds and measures hearing thresholds.

Transducers

Devices delivering sound to the ear: earphones, inserts, bone vibrator, or speakers.

Supra-aural earphones

Earphones worn over the pinna for testing.

Insert earphones

Disposable foam-tipped earphones inserted into the ear canal; reduce ear canal collapse and improve hygiene.

Bone conduction vibrator

Device placed on the mastoid or forehead to deliver vibrations to the skull.

Circumaural earphones

Over-ear earphones used for extended high-frequency testing.

Soundfield testing

Testing with loudspeakers in the room; thresholds reflect the better ear and are not ear-specific.

Warble tone

Frequency-modulated tone used to help testing or to mask tinnitus.

Narrowband noise

Band-limited noise used for masking or soundfield testing.

Speech noise

Noise used to mask during speech testing.

White noise

Broad-spectrum noise used as masking noise.

Calibration

Process of ensuring audiometer outputs meet national standards; usually annually.

Sound booths

Sound-attenuated rooms where audiometry is conducted; checked annually.

Case history

Medical and background information collected before testing.

Otoscopy

Visual inspection of the ear canal and tympanic membrane before testing.

Threshold

Softest level at which a stimulus can be heard 50% of the time.

50% detection

Probability threshold where the tone is heard on half of trials.

dB HL vs dB SPL

dB HL refers to normal-threshold-based hearing; dB SPL is a physical sound level.

Air conduction testing

Testing through the normal hearing pathway using earphones or soundfield.

Collapsing ear canal

Compression of the ear canal under earphone pressure, potentially causing false thresholds.

Insert earphones infection control

Disposable tips reduce cleaning demands and infection risk.

Bone conduction testing

Assessing sensorineural pathways by vibrating the skull.

Mastoid

Bony region behind the ear where bone conduction vibrator can be placed.

Forehead

Alternative bone-conduction placement site on the skull.

Threshold procedure

Procedural steps to determine hearing thresholds.

30 dBHL

Initial search level for most thresholds.

50 dBHL

Next step if no response at 30 dBHL; used to begin threshold search.

10 down 5 up rule

Rule used after initial detection to refine threshold.

Two crossover points

Requirement of at least two responses around threshold to confirm it.

AC frequencies

Air-conduction frequencies tested: 250 Hz, 500 Hz, 1k, 2k, 3k, 4k, 6k, 8k Hz.

250 Hz

Low-frequency test frequency in AC testing.

500 Hz

AC test frequency; mid-low frequency.

1 kHz

Core speech-range test frequency.

2 kHz

AC test frequency; important for high-frequency slope.

3 kHz

AC test frequency; recommended by ASHA in modern guidelines.

4 kHz

AC test frequency contributing to high-frequency assessment.

6 kHz

AC test frequency for extended high-frequency testing.

8 kHz

AC test frequency for extended high-frequency testing.

Inter-octave 750 Hz

Inter-octave tested frequency between 500 and 1,000 Hz.

Inter-octave 1.5 kHz

Inter-octave tested frequency between 1 and 2 kHz.

BC frequencies

Bone-conduction frequencies tested: 500 Hz, 1k, 2k, 4k Hz; 6k/8k less common.

500 Hz (BC)

Bone conduction test frequency at 500 Hz.

1 kHz (BC)

Bone conduction test frequency at 1 kHz.

2 kHz (BC)

Bone conduction test frequency at 2 kHz.

4 kHz (BC)

Bone conduction test frequency at 4 kHz.

Audiogram

Graph plotting thresholds (dB HL) vs frequency.

dB HL on audiogram

Scale labeling thresholds in dB HL on the graph.

Normal hearing range

Ranges up to 25 dB HL for normal hearing.

Degrees of hearing loss

Classification of impairment severity from normal to profound.

Normal (−10 to 25)

Degree range considered normal.

Mild (26–40)

Light hearing loss category.

Moderate (41–55)

Moderate hearing loss category.

Moderately-severe (56–70)

Moderately-severe loss category.

Severe (71–90)

Severe loss category.

Profound (91+)

Profound hearing loss category.

Right Air conduction (symbol)

O is used for right ear air conduction on audiogram.

Left Air conduction (symbol)

X is used for left ear air conduction on audiogram.

Right Bone conduction (symbol)

< symbol for right ear bone conduction.

Left Bone conduction (symbol)

symbol for left ear bone conduction.

Soundfield (symbol)

S on audiogram indicates thresholds obtained with speakers.

No response (symbol)

Downward arrow indicates no response at a tested frequency.

Masking

Noise introduced to non-test ear to isolate the test ear.

Air conduction masking

Masking used for AC when interaural attenuation causes crossover.

Masking noise

Noise used to mask the non-test ear.

Interaural Attenuation (IA)

Reduction of signal energy to the non-test ear in AC testing.

Air-bone gap

Difference between AC and BC thresholds; indicates conductive involvement.

Conductive hearing loss

Outer or middle ear problem; BC normal; AC abnormal; air-bone gap ≥15 dB.

Sensorineural hearing loss

Inner ear or auditory nerve problem; AC and BC abnormal; typically no air-bone gap.

Mixed hearing loss

Both conductive and sensorineural components; AC worse than BC; air-bone gap ≥15 dB.

Unilateral

Hearing loss in one ear only.

Bilateral

Hearing loss in both ears.

Symmetrical

Same degree/configuration in both ears.

Asymmetrical

Different degree/configuration between ears; often ≥15 dB at two consecutive frequencies.

Sloping

Configuration with greater loss at high frequencies.

Rising

Greater loss at low frequencies.

Flat

Thresholds roughly equal across frequencies.

Notch

Drop at one or two frequencies; notches in the audiogram.

Cookie bite (saucer notch)

Notch with mid-frequency relief, resembling a cookie bite.

PTA (Pure Tone Average)

Average of AC thresholds at 500, 1000, and 2000 Hz.

PTA calculation

(500 + 1000 + 2000) ÷ 3.

PTA as cross-check

Used to corroborate speech testing results.

Example PTA (RE)

RE PTA example: (10+5+10)/3 ≈ 8 dB HL.

Example PTA (LE)

LE PTA example: (5+10+5)/3 ≈ 7 dB HL.

ASHA guideline: include 3k and 6k

Guidelines recommend including 3k and 6k Hz in testing for every patient.

Threshold search refinement

Apply 10 dB down and 5 dB up steps to refine threshold.

Response methods

Patient responses can be via hand signals, button press, or verbal.

Occluding cerumen

Removing earwax to ensure accurate testing.

Case data utility

Audiometry data informs degree, type, and configuration of hearing loss.

Masking notation

Masking status (masked/unmasked) indicated in test results.

Cross-check with speech testing

PTA or threshold results are compared with speech testing results.

Air conduction vs bone conduction explanation

AC tests all parts of the ear; BC tests cochlear function only.

Air conduction minus bone conduction equals air-bone gap

Difference between AC and BC thresholds indicating conductive involvement.