Exam 2 Audio Eval

SRT

Quietest level you can repeat 2-syllable words (spondees) half the time. Units: dB HL.

WRS

Percent of one-syllable words repeated correctly, tested LOUD (30-40 dB above SRT). Units: %.

SRT should match your ___ within ___ dB

PTA; 10 dB

No SRT? Use the ___ instead

PTA

Is SRT a threshold or suprathreshold test?

Threshold (quietest level)

Is WRS a threshold or suprathreshold test?

Suprathreshold (loud, above threshold)

SDT/SAT: patient only has to…

Notice that speech is there (not understand it). About 10 dB better than SRT.

PBmax means

Your BEST word recognition score at any level

Rollover means

Score gets WORSE when the speech gets louder

Rollover index formula

(PBmax - PBmin) / PBmax

Rollover index example: PBmax 64%, PBmin 38%

(64-38)/64 = 0.41. Over 0.4 = significant

A rollover index over ___ is significant

0.4 (suggests retrocochlear, but does not prove it)

Normal hearing: expected WRS

About 90-100%

Conductive loss: expected WRS

About 90-100% (just make it louder)

Cochlear loss: expected WRS

WRS is generally consistent with the degree of hearing loss

Retrocochlear loss: WRS pattern

Lower than the chart predicts and/or rollover

Dubno graph: what the dots show

PTA (across) vs best word score (up). Dashed line = lowest normal score for that PTA.

Score BELOW the dashed line on the Dubno graph means

Disproportionately low WRS: possible retrocochlear

SPRINT chart: how to read it

Find PTA on the left, WRS across the top. White box = as expected. Gray box = too low.

SPRINT: PTA 60, WRS 60

White zone = as expected for a cochlear loss

SPRINT: PTA 40, WRS 50 (Alfred)

Gray zone = lower than expected; retest at a higher level; if still low, think retrocochlear

SPRINT: acoustic neuroma, PTA 40. Expected WRS?

Below the cutoff for PTA 40 (under about 60%), which is the gray zone. A cochlear loss would score above it.

A gray-zone WRS: what do you do first?

Retest at a second, higher level (maybe PBmax was not reached)

Do the SPRINT/Dubno charts work for conductive loss?

No. SNHL only.

Fletcher average

Average of the 2 BEST thresholds out of 500, 1000, 2000 Hz. Used for steeply sloping loss.

Dynamic range formula

UCL minus SRT. Example: 100 - 45 = 55 dB

Recruitment makes dynamic range

Smaller (quiet is inaudible, loud is very loud)

MCL

Most comfortable level (about 40-55 dB above SRT)

UCL

Level that is uncomfortable (not painful)

Longer word lists give scores that are

More reliable (less variable)

Kids who cannot repeat words: use

Picture-pointing tests (WIPI, NU-CHIPS)

Masking: why?

Stop the NON-test ear from answering the test ear's tone

Crossover

Tone from the test ear travels through the skull to the other cochlea. ALWAYS happens.

Cross-hearing

The other ear actually HEARS the crossover. (Crossover can happen without it.)

The ___ cochlea always responds

Best (better) cochlea

IA for supra-aural earphones

40 dB

IA for insert earphones

70 dB

IA for bone conduction

0 dB

AC masking step 1

Crossover = test-ear AC minus IA

AC masking step 2

Is crossover >= the OTHER ear's BC? If yes, MASK.

AC masking: R AC 60, L BC 10, supra-aural

60 - 40 = 20. 20 >= 10. MASK the left ear.

AC masking: R AC 50, L BC 0, supra-aural

50 - 40 = 10. 10 >= 0. MASK.

AC masking: R AC 90, L BC 10, supra-aural

90 - 40 = 50. 50 >= 10. MASK.

AC masking: R AC 30, L BC 20, supra-aural

30 - 40 = -10. -10 is NOT >= 20. NO mask.

AC masking: R AC 80, L BC 0, INSERTS

80 - 70 = 10. 10 >= 0. MASK.

No BC at 8 kHz: mask when AC difference between ears is at least

40 dB (supra-aural) or 70 dB (inserts)

BC masking rule

Mask when the test ear's air-bone gap is 15 dB or more

Air-bone gap formula

AC minus BC

BC masking: R AC 45, R BC 25

Gap 20 = 15 or more. MASK.

BC masking: R AC 45, R BC 30

Gap 15. MASK.

BC masking: L AC 20, L BC 10

Gap 10. NO mask.

Why is BC masking about the air-bone gap?

IA is 0, so you can't tell which cochlea answered when the test ear has a gap

Air rule or bone rule: 'AC minus IA'

Air conduction rule

Air rule or bone rule: 'gap of 15'

Bone conduction rule

Where does the masking noise go?

The NON-test ear

Best noise for pure-tone masking

Narrowband noise

Masked right AC symbol

Triangle

Masked left AC symbol

Square

Masked right BC symbol

[

Masked left BC symbol

]

Undermasking

Noise too soft; non-test ear can still answer

Overmasking

Noise so loud it crosses over and raises the TEST ear's threshold

Plateau

Test-ear threshold stays the same as masker goes up. This is the goal.

Masking dilemma

No safe level between too little and too much. Classic: both ears conductive with big gaps.

Tympanogram shows

How easily the middle ear moves (admittance) as ear-canal pressure changes

Normal probe tone for adults

226 Hz

Three parts of the tymp probe

Speaker, air pump, microphone

Normal peak pressure range

-150 to +25 daPa

Type A

Normal. Also seen with sensorineural loss.

Type As

Shallow peak = STIFF (example: stapes fixation)

Type Ad

Very tall peak = FLOPPY (example: ossicular disarticulation)

Type B

Flat. Look at the ear-canal volume to decide why.

Type C

Peak shifted to negative pressure: Eustachian tube problem / resolving ear infection

Type B + normal volume

Fluid behind the eardrum

Type B + small volume

Blocked canal (earwax)

Type B + large volume

Hole in the eardrum or open PE tube

Normal adult ear-canal volume

0.9 - 2.0 cc (child: 0.3 - 0.9 cc)

Mild sensorineural loss, normal ear exam: tymp?

Type A

Ear infection: tymp?

Type B with normal volume

Earwax plug: tymp?

Type B with small volume

Eardrum perforation: tymp?

Type B with large volume (and conductive loss)

Can a tympanogram tell you the hearing loss amount?

No. It only tests middle-ear function.

Acoustic reflex =

Loud sound makes both stapedius muscles tighten (bilateral)

Reflex nerve path

IN: CN VIII (hearing nerve). OUT: CN VII (facial nerve).

Stimulus ear

The ear that gets the LOUD sound. Names the condition.

Probe ear

The ear where the change is MEASURED

Right ipsi

Stimulus R, probe R

Left ipsi

Stimulus L, probe L

Right contra

Stimulus R, probe L

Left contra

Stimulus L, probe R

Normal ears: reflexes

Present in all 4 conditions

CN VIII lesion: reflexes go absent when the bad ear is the ___ ear

STIMULUS ear

CN VII lesion: reflexes go absent when the bad ear is the ___ ear

PROBE ear

Right CN VIII lesion: which conditions absent?

Right ipsi and Right contra

Right CN VII lesion: which conditions absent?

Right ipsi and Left contra

Conductive loss in the PROBE ear

Reflex ABSENT (can't measure it)

Conductive loss in the STIMULUS ear

Reflex threshold raised by the air-bone gap; absent if gap over 30 dB

Both ears conductive: reflexes

Absent in all four

Cochlear hearing loss 80 dB HL or less: reflex

Present

Cochlear hearing loss over 80 dB HL: reflex

Absent