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What does the outer ear do?

Collects and funnels sound into the ear canal toward the eardrum

What does the middle ear do?

Transmits vibration from the eardrum to the inner ear via the ossicles (TM + ossicles)

What does the inner ear do?

Transduces sound into a neural signal and supports balance (cochlea + vestibular organs)

What structures make up the conductive mechanism?

Outer ear + middle ear — transfers acoustic energy toward the cochlea

What structures make up the sensorineural mechanism?

Cochlea + CN VIII (auditory nerve) + central pathways — transduces and carries the signal

What does "pathway" mean in audiology (air vs. bone conduction)?

The route sound energy takes to reach the cochlea — through air, or through bone/skull vibration

What does "mechanism" mean in audiology (conductive vs. sensorineural)?

Which part of the auditory system is impaired — the conductive (outer/middle ear) or sensorineural (cochlea/nerve) part

What is the air conduction (AC) pathway?

Ear canal -> TM -> ossicles -> cochlea -> auditory nerve

What does bone conduction (BC) bypass, and what does it NOT bypass?

Largely bypasses outer + middle ear; still depends on the cochlea/sensorineural system

Name two common causes of a conductive component.

Cerumen impaction and otitis media (middle-ear fluid)

How do you perform the Rinne test?

Place fork on the mastoid; when no longer heard, move it beside the ear canal

What does a positive Rinne mean?

AC heard longer/louder than BC — typical in normal hearing or SNHL

What does a negative Rinne mean?

BC heard longer/louder than AC — suggests a conductive component

How do you perform the Weber test?

Place the vibrating fork at midline (e.g., forehead) and ask where it's heard

In a unilateral conductive loss, which way does Weber lateralize?

Toward the poorer (conductive) ear

In a unilateral sensorineural loss, which way does Weber lateralize?

Toward the better ear (the healthier cochlea)

How do you perform the Bing test?

Fork on the mastoid, alternately occluding and opening the ear canal

What's the difference between positive and negative Bing?

Positive = louder with occlusion (normal/SNHL); Negative = little/no change (suggests conductive)

How do you perform the Schwabach test?

Fork on patient's mastoid; when they stop hearing it, move it to the examiner's mastoid

Patient stops hearing the BC tone before a normal-hearing examiner — what does that suggest?

Likely sensorineural hearing loss

Patient hears the BC tone LONGER than the examiner — what does that suggest?

A conductive component, which can boost perceived BC duration

What is the occlusion effect?

Closing the ear canal traps more low-frequency BC energy, increasing perceived BC loudness — basis of the Bing test

What is the Stenger principle?

If two identical tones differing only in loudness are presented to both ears at once, only the louder one is perceived

What is dB SPL referenced to?

A fixed physical sound pressure, 20 microPa

What is the formula for dB SPL?

dB SPL = 20 x log10(measured pressure / 20 microPa)

What is dB IL referenced to, and what's its formula?

10^-12 W/m^2; dB IL = 10 x log10(measured intensity / 10^-12 W/m^2)

What is dB HL referenced to?

The average threshold of normal-hearing listeners, for a specific frequency and transducer

What is RETSPL?

The dB SPL that corresponds to 0 dB HL, for a given frequency and transducer

How do you convert dB SPL to dB HL?

SUBTRACT the RETSPL from the dB SPL value

How do you convert dB HL to dB SPL?

ADD the RETSPL to the dB HL value

What is dB SL and its formula?

Level above the listener's own threshold; dB SL = presentation level - individual threshold

A tone's dB SL is negative — what does that mean?

The tone is below the person's threshold and should not be audible

How do two independent, equal-intensity sound sources combine in dB?

They add about 3 dB total, not double the value — the scale is logarithmic

What is the traditional pure-tone average (PTA), and how is it calculated?

Average of AC thresholds at 500, 1000, and 2000 Hz for one ear

What's the WNL (within normal limits) cutoff used in this course?

<=25 dB HL

What is an air-bone gap (ABG)?

The difference between the AC and BC thresholds at the same frequency

At what size is an ABG considered clinically significant?

Greater than 10 dB

BC is WNL and there's a significant ABG — what type of loss?

Conductive hearing loss

BC is NOT WNL, little/no ABG — what type of loss?

Sensorineural hearing loss

BC is NOT WNL AND there's a significant ABG — what type of loss?

Mixed hearing loss

What are the degree-of-hearing-loss categories, normal to profound?

Normal <=25, Mild 26-40, Moderate 41-55, Mod-severe 56-70, Severe 71-90, Profound >90 (dB HL)

What does "laterality" describe?

Whether hearing loss is in one ear (unilateral) or both (bilateral)

What does "symmetry" describe?

Whether the two ears are similar (symmetric) or meaningfully different (asymmetric)

What is "configuration"?

Shape of the threshold curve across frequency: flat, sloping, rising, notch, cookie-bite, precipitous

Why is masking necessary during audiometric testing?

A tone can cross over to the non-test ear; masking noise ensures the response comes from the test ear

Maria: threshold 3000 microPa at 500 Hz, supra-aural. What's this in dB SPL?

About 43.5 dB SPL (20 x log10(3000/20))

Convert Maria's 43.5 dB SPL (500 Hz, supra-aural, RETSPL=13) to dB HL.

30.5 dB HL (43.5 - 13)

Tone presented to Maria at 45 dB HL, her threshold is 30.5 dB HL — dB SL and audibility?

+14.5 dB SL — audible

Tone at 25 dB HL, 2000 Hz, insert earphones, RETSPL=3 — what's the dB SPL?

28 dB SPL (25 + 3)

Two independent machines each at 65 dB IL — combined level?

About 68 dB IL (adds ~3 dB, not double)

AC thresholds 20, 30, 25 dB HL at 500/1000/2000 Hz — what's the PTA?

25 dB HL ((20+30+25)/3)

Threshold at 4000 Hz is 40 dB HL, tone presented at 25 dB HL — dB SL and audibility?

-15 dB SL — not audible