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The Pure Tone Audiogram (PTA) - Complete Master Guide

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1. WHAT IS A PTA AUDIOGRAM?

• It tells you how much hearing loss is present (degree)
• It tells you what type of hearing loss (conductive, sensorineural, mixed)
• Certain disease patterns produce characteristic audiogram "shapes"

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2. THE GRAPH ITSELF

X-axis: FREQUENCY (Hz) - Pitch

• Runs left to right: low pitch to high pitch
• Logarithmic scale (each octave takes equal space)
• Standard frequencies tested: 250, 500, 1000, 2000, 4000, 8000 Hz
• Inter-octave frequencies (750, 1500, 3000, 6000 Hz) added when:
  • Threshold difference of ≥25 dB between adjacent octaves
  • Ototoxicity monitoring
  • Hearing aid fitting
• Speech frequencies: 500-4000 Hz (this is the clinically critical zone)
• 250 Hz ≈ middle C on a piano

Y-axis: HEARING LEVEL (dB HL) - Loudness

• Runs top to bottom (0 at top, 120 at bottom) - this is the opposite of a normal graph
• 0 dB HL = average threshold of a normal young adult (not silence)
• Negative numbers (-10 dB) mean hearing is better than average
• The lower the threshold mark, the worse the hearing (more loss = lower on the graph)
• Units are dB HL (hearing level) - already corrected for the ear's frequency sensitivity. Different from dB SPL.

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3. AUDIOGRAM SYMBOLS (ASHA Standard)

Full Symbol Table

Colour convention

• Red = Right ear
• Blue = Left ear

Line convention

• AC thresholds joined by solid lines
• BC thresholds joined by dashed lines

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4. WHAT IS MEASURED: AIR vs BONE CONDUCTION

Air Conduction (AC)

Bone Conduction (BC)

Why this matters clinically

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5. THE AIR-BONE GAP (ABG)

• Normal: ABG = 0 (both lines overlap)
• Significant ABG: ≥10 dB (StatPearls says >15 dB HL)
• ABG = sign of conductive pathology (outer or middle ear problem)

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6. MASKING

• Supra-aural headphones AC: 40-65 dB IA (crossover risk at ≥40 dB HL)
• Insert earphones AC: 70-90 dB IA (much less crossover risk)
• Bone conduction: 0-10 dB IA (crossover happens almost immediately - always consider masking)

1. AC: Mask the non-test ear when the AC level in the test ear exceeds the BC threshold of the non-test ear by 40 dB (supra-aural) or 55 dB (insert)
2. BC: Mask the non-test ear whenever you test bone conduction (because IA for BC ≈ 0-10 dB)

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7. DEGREE OF HEARING LOSS

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8. PURE-TONE AVERAGE (PTA)

• Summarizes hearing in the key speech frequencies
• Used to classify degree of hearing loss
• Limitation: Does NOT reflect high-frequency hearing loss (e.g., early noise-induced or presbycusis affecting 4000-8000 Hz)

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9. AUDIOGRAM SHAPES (CONFIGURATIONS)

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10. THE THREE TYPES OF HEARING LOSS

A. Conductive Hearing Loss (CHL)

• AC abnormal, BC normal (≤20 dB HL)
• Air-bone gap present (≥10-15 dB)
• Problem in: outer ear or middle ear

• Cerumen impaction
• Otitis media with effusion ("glue ear")
• Tympanic membrane perforation
• Otosclerosis (stapes fixation)
• Ossicular chain disruption

B. Sensorineural Hearing Loss (SNHL)

• Both AC and BC are equally abnormal
• No air-bone gap (lines overlap or gap <10 dB)
• Problem in: cochlea (sensory) or auditory nerve/CNS (neural)

• Presbycusis (age-related) - bilateral sloping high-frequency loss
• Noise-induced - 4 kHz notch
• Meniere's disease - low-frequency, fluctuating
• Acoustic neuroma (vestibular schwannoma) - unilateral
• Ototoxic drugs (aminoglycosides, cisplatin)
• Viral/genetic causes

C. Mixed Hearing Loss

• Both AC and BC abnormal
• Air-bone gap also present (both are impaired but BC is better than AC)
• Problem in: both outer/middle ear AND cochlea

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11. NORMAL AUDIOGRAM

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12. DISEASE-SPECIFIC AUDIOGRAM PATTERNS (HIGH-YIELD)

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13. THE AUDIOGRAM OF FAMILIAR SOUNDS ("Speech Banana")

• Vowels (a, e, o, u) fall in low frequencies (250-1000 Hz), moderate intensity (40-60 dB)
• Consonants (f, s, th) fall in high frequencies (2000-8000 Hz), low intensity (10-20 dB)
• The cluster of speech sounds forms a banana shape from lower-left to upper-right
• If a patient's thresholds fall below the speech banana, those sounds are inaudible to them
• This explains why high-frequency SNHL causes difficulty understanding consonants even when they can "hear" speech

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14. WHAT THE AUDIOGRAM DOES NOT SHOW

• Speech discrimination/intelligibility in noise (needs speech audiometry)
• Central auditory processing
• Cochlear mechanics (needs OAEs - otoacoustic emissions)
• Neural synchrony (needs ABR - auditory brainstem response)
• Middle ear function (needs tympanometry)
• Uncomfortable loudness levels (needs loudness testing)

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15. THE TEST PROCEDURE (How PTA is Performed)

1. Patient sits in a sound-treated booth to eliminate ambient noise
2. Otoscopic inspection first (check for cerumen, perforation, etc.)
3. Earphones placed (supra-aural or insert)
4. Tones presented using the Hughson-Westlake method:
   • Start at 1000 Hz at a comfortable level
   • Patient responds (button/hand raise) every time they hear a tone
   • Decrease in 10 dB steps, increase in 5 dB steps
   • Threshold = lowest level with ≥50% correct responses
5. Order: typically 1000 → 2000 → 4000 → 8000 → 500 → 250 Hz; retest 1000 Hz for reliability
6. Better ear tested first
7. Bone conduction if AC ≥15 dB HL
8. Masking applied as needed

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16. QUICK INTERPRETATION PROTOCOL (Step-by-Step)

• Normal BC + abnormal AC + ABG → Conductive
• Abnormal BC + abnormal AC + no ABG → Sensorineural
• Both abnormal + ABG present → Mixed

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17. KEY NUMBERS TO MEMORIZE

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Tympanometry and the Stapedial (Acoustic) Reflex - Complete Master Guide

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PART 1: TYMPANOMETRY

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1. WHAT IS TYMPANOMETRY?

• It does not test hearing - it tests middle ear mechanics
• It measures acoustic immittance (admittance = how easily sound energy enters the middle ear; impedance = opposition to sound flow - they are reciprocals)
• Results are displayed as a tympanogram - a graph of compliance vs pressure
• Performed with a tympanometer (probe inserted into the ear canal with an airtight seal)

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2. THE TYMPANOGRAM GRAPH

• Normal static compliance: 0.3-1.6 mL (adults)
• Normal peak pressure: -100 to +50 daPa (adults)

• Peak compensated static admittance (height of the peak)
• Tympanometric peak pressure (TPP) - pressure at which peak occurs
• Tympanometric width (TW) / Gradient - width of the curve at half the peak height (normal ~60-150 daPa; widened in OME)
• Equivalent ear canal volume (ECV) - volume of air in front of the probe (normal 0.6-1.5 mL adults; 0.3-0.9 mL children)

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3. TYMPANOGRAM TYPES (JERGER CLASSIFICATION)

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TYPE A - NORMAL

• Peak at 0 daPa (or close: -100 to +50 daPa in adults)
• Normal compliance height
• Indicates: Normal middle ear pressure and normal TM mobility
• Seen in: Normal hearing OR sensorineural hearing loss (inner ear problem, but middle ear is fine)

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TYPE As (A-shallow / A-stiff)

• Peak is at normal pressure but compliance is abnormally LOW (shallow peak)
• "s" = shallow/stiffened
• Indicates: Increased stiffness of the middle ear system
• Seen in:
  • Otosclerosis (fixation of stapes footplate)
  • Tympanosclerosis
  • Scarred/thickened tympanic membrane
  • Malleus fixation

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TYPE Ad (A-deep / A-discontinuous)

• Peak is at normal pressure but compliance is abnormally HIGH (very tall, sharp peak)
• "d" = deep/discontinuous
• Indicates: Hypercompliant / flaccid middle ear
• Seen in:
  • Ossicular chain discontinuity (e.g., traumatic disruption of incus)
  • Flaccid/atrophic tympanic membrane (monomeric)
  • Healed large perforation
• Note: In discontinuity there is often a severe conductive hearing loss, worse at high frequencies (unlike most CHL)

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TYPE B - FLAT

• No identifiable peak across the pressure sweep
• The curve is flat or gently rounded
• Now look at the ear canal volume (ECV) - this is the key discriminator:

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TYPE C - NEGATIVE PRESSURE

• Peak present but shifted to negative pressure (more negative than -100 daPa adults, -150 daPa children)
• Subtypes:
  • C1: -100 to -199 daPa
  • C2: -200 to -399 daPa (more significant)
• Indicates: Negative middle ear pressure - Eustachian tube dysfunction
• Seen in: Eustachian tube obstruction, early OME, after URI, retracted TM
• C2 + Type B combined has sensitivity 73-99% for OME

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SUMMARY TABLE

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4. CLINICAL APPLICATIONS OF TYMPANOMETRY

• Diagnosing OME (otitis media with effusion) - key test alongside otoscopy
• Detecting TM perforation (large ECV)
• Checking PE tube patency (large ECV if patent)
• Screening for middle ear pathology in children
• Confirming conductive hearing loss cause
• Combined with otoscopy: When both agree (Type B + otoscopy = OME), sensitivity 98%; specificity 98%

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5. LIMITATIONS

• Does NOT test hearing directly
• Unreliable in infants <7 months with standard 226 Hz probe (use 1000 Hz)
• Cannot be performed with TM perforation for standard immittance testing
• Does not distinguish all causes of Type B (need ECV to help)

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PART 2: THE STAPEDIAL (ACOUSTIC) REFLEX

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6. WHAT IS THE STAPEDIAL REFLEX?

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7. THE REFLEX ARC

Ipsilateral Pathway (stimulus and recording in SAME ear)

1. Cochlea (hair cells)
2. CN VIII (auditory nerve)
3. Ipsilateral ventral cochlear nucleus (VCN)
4. Trapezoid body
5. Ipsilateral facial motor nucleus (or medial superior olive)
6. Ipsilateral CN VII (facial nerve)
7. Ipsilateral stapedius muscle contracts

Contralateral Pathway (stimulus in ONE ear, recording in OTHER ear)

1. Cochlea (hair cells)
2. CN VIII (auditory nerve)
3. Ipsilateral VCN
4. Crosses to contralateral medial superior olive
5. Contralateral facial motor nucleus
6. Contralateral CN VII (facial nerve)
7. Contralateral stapedius muscle contracts

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8. HOW IT IS TESTED

• Tympanometer set to hold TM at point of maximum compliance
• Pure tones or broadband noise presented at increasing intensities
• The reflex threshold = lowest level that produces a change in compliance
• Tested ipsilaterally (probe = recording ear also gets the sound) and contralaterally (probe records in one ear; sound in the other)
• Normal reflex threshold: 70-100 dB HL for pure tones

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9. RECORDING ARRANGEMENT - UNDERSTANDING THE 4 COMBINATIONS

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10. CAUSES OF ABSENT OR ELEVATED ACOUSTIC REFLEX

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11. PATTERNS OF REFLEX FINDINGS (LESION LOCALISATION)

• Tympanogram: Type As (stiffened)
• Reflex: Absent (stapes is fixed, cannot move)
• Useful to contrast with "third window" lesions (superior semicircular canal dehiscence): Type A tympanogram, reflex present, cochlear conductive hearing loss pattern

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12. ACOUSTIC REFLEX DECAY TEST

• Cochlear SNHL: Normal reflex thresholds (or slightly elevated) - no decay
• Neural SNHL (acoustic neuroma): Reflex may be elevated, absent, or present with rapid decay

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13. REFLEX THRESHOLD AND TYPE OF HEARING LOSS

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14. COMBINING TYMPANOMETRY + REFLEX: THE IMMITTANCE BATTERY

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15. KEY NUMBERS TO MEMORISE

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OAE, ECoG, BERA/ABR, Decay Test & Speech Audiometry - Complete Master Guide

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PART 1: OTOACOUSTIC EMISSIONS (OAE)

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1. WHAT ARE OAEs?

• OAEs are absent if OHCs are damaged (≥35-40 dB HL of cochlear hearing loss typically abolishes them)
• They test OHC integrity only - not inner hair cells, not auditory nerve, not brainstem
• They are objective - patient does not need to respond; unaffected by sedation, anesthesia, sleep, arousal, cognitive status, language
• They cannot be recorded if middle ear is abnormal (fluid, perforation → check tympanogram first)

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2. TYPES OF OAE

A. Spontaneous OAEs (SOAEs)

• Occur without any external stimulus
• Found in ~50-60% of normal-hearing ears
• Not used clinically (inconsistent)

B. Evoked OAEs (clinical use):

• Stimulus: Brief click or tone burst
• The cochlea produces a delayed "echo" after the click
• Response spans 0.4-6 kHz; latency 5-20 ms
• Used for: Newborn hearing screening, general OHC function assessment
• Readout: Waveform reproducibility (>70% acceptable) + amplitude (signal vs noise)
• Advantages: Fast, broadband frequency coverage

• Stimulus: Two simultaneous pure tones (f1 and f2) at 55-85 dB SPL
• The nonlinear OHCs generate a distortion product at frequency: 2f₁ - f₂ (e.g., f₁ = 2000 Hz, f₂ = 2500 Hz → DPOAE at 1500 Hz)
• Ratio f₂/f₁ = 1.22 is optimal; f₂ level 10-15 dB lower than f₁
• The DPOAE amplitude is ~60 dB below the primary tone levels
• Used for: Frequency-specific OHC mapping, monitoring ototoxicity, monitoring noise exposure
• Displayed as a DP-gram (DPOAE amplitude vs frequency)
• Advantages: Frequency-specific - can track changes at specific cochlear regions

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3. INTERPRETING OAEs

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4. CLINICAL APPLICATIONS OF OAEs

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5. FACTORS THAT AFFECT OAEs

• Sleep/arousal state
• Sedation or anesthesia
• Body position
• Motivation / cognitive status
• Language barriers

• Middle ear pathology (must have normal tympanogram)
• Degree of hearing loss (absent if >35-40 dB HL cochlear loss)
• Probe fit / cerumen
• Ambient noise in test room

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PART 2: ELECTROCOCHLEOGRAPHY (ECoG / ECochG)

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6. WHAT IS ECoG?

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7. ELECTRODES USED

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8. THE SP/AP RATIO - DIAGNOSTIC KEY

• Normal: SP is a small shoulder/deflection before the AP; ratio is low
• Endolymphatic hydrops (Meniere's disease): Basilar membrane is distorted → SP amplitude increases relative to AP → elevated SP/AP ratio

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9. CLINICAL APPLICATIONS OF ECoG

1. Meniere's disease / endolymphatic hydrops - elevated SP/AP ratio (primary use)
2. Auditory Neuropathy Spectrum Disorder (ANSD) - CM present (OHCs intact) but AP/ABR absent (nerve dysfunction)
3. Intraoperative monitoring of cochlear function
4. Threshold estimation (largely replaced by ABR now)
5. Enhancing Wave I of ABR when it is absent or difficult to identify (helps interpeak latency measurements)
6. Acoustic neuroma detection (largely replaced by ABR + MRI)

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PART 3: AUDITORY BRAINSTEM RESPONSE (ABR / BERA)

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10. WHAT IS ABR/BERA?

• Objective test - requires no patient response
• NOT affected by: sedation, sleep, most anesthetics, drugs, arousal state
• IS affected by: body temperature (latencies change), sex (females have slightly shorter latencies), age, degree of hearing loss
• Stimulus: Click (100 µs rectangular pulse, broad spectrum, activates basal cochlea = 2000-4000 Hz region) or tone bursts for frequency-specific threshold testing
• Recording: Surface electrodes on forehead/vertex (non-inverting), earlobe/mastoid (inverting), forehead centre (ground)
• 1000-3000 sweeps are averaged to reduce noise

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11. THE ABR WAVEFORM - WAVES I TO V

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12. NORMAL INTERPEAK LATENCIES (CRITICAL NUMBERS)

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13. ABR USES

A. Threshold ABR (Hearing Estimation)

• Click ABR correlates with pure-tone thresholds at 2000-4000 Hz
• Tone-burst ABR gives frequency-specific thresholds
• Used for: Newborns, uncooperative patients, malingering, medico-legal
• Wave V threshold correlates to behavioural threshold +10-15 dB (click-ABR)

B. Neurodiagnostic ABR (Retrocochlear screening)

• High stimulus level: 80-95 dB nHL
• Screens for acoustic neuroma / vestibular schwannoma and brainstem lesions
• Sensitivity for acoustic neuroma: >90% in older studies; modern MRI has largely replaced it but ABR used when MRI contraindicated

1. I-V interpeak latency >4.4 ms
2. I-III interpeak latency >2.3 ms
3. III-V interpeak latency >2.1 ms
4. Interaural wave V latency difference >0.2-0.4 ms
5. Absent wave V with preserved wave I or III ← definitive sign
6. Complete absence of ABR (if not explained by degree of hearing loss)

C. Intraoperative monitoring

• Real-time monitoring during CPA surgery (acoustic neuroma resection, microvascular decompression)
• Changes in wave V latency or amplitude warn surgeon of traction on CN VIII

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14. ABR IN AUDITORY NEUROPATHY SPECTRUM DISORDER (ANSD)

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PART 4: THE DECAY TEST (Tone Decay Test)

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15. WHAT IS TONE DECAY?

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16. PERFORMING THE TEST

1. Present a continuous tone at 5 dB above threshold for 60 seconds
2. Patient signals as long as they hear it
3. If perception fades before 60 seconds, raise level by 5 dB
4. Continue raising until audible for the full 60 seconds
5. The total rise in dB above threshold = the decay value

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17. INTERPRETING TONE DECAY

• As speech level increases, WRS normally improves then plateaus
• If WRS falls (rollover) at higher levels = retrocochlear lesion
• Retrocochlear lesions → "rollover phenomenon" - discrimination worsens at louder levels

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18. SUMMARY: COCHLEAR vs RETROCOCHLEAR DIFFERENTIATION

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PART 5: SPEECH AUDIOMETRY

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19. WHAT IS SPEECH AUDIOMETRY?

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20. COMPONENTS OF SPEECH AUDIOMETRY

A. Speech Awareness/Detection Threshold (SAT / SDT)

• Lowest level at which patient can detect the presence of speech (not identify it)
• Used when SRT cannot be obtained (children, language barriers, cognitive impairment)
• Should agree with the best pure-tone threshold within 10 dB anywhere on the audiogram (speech is a complex broad-band signal)
• Typically 5-10 dB better than SRT

B. Speech Recognition Threshold (SRT)

• Lowest level at which patient can correctly repeat spondee words in 50% of presentations
• Spondee = two-syllable compound word with equal stress on both syllables
  • Examples: railroad, sidewalk, eardrum, baseball, hotdog, airplane, birthday
• Key relationship: SRT should be within ±10 dB of the PTA (500 + 1000 + 2000 Hz ÷ 3)
  • If SRT and PTA disagree by >10 dB → consider non-organic hearing loss (malingering), or use 2-frequency best PTA for sloping audiograms

1. Confirms PTA accuracy
2. Establishes reference point for WRS testing
3. Detects non-organic hearing loss (functional/malingering)

C. Word Recognition Score (WRS) / Speech Discrimination Score (SDS)

• Percentage of phonetically balanced (PB) words correctly repeated
• Presented at 25-35 dB above SRT (sensation level) - this is the "most comfortable level" range
• Uses PB word lists (phonemes occur in same proportions as in natural English)
• UK/ENT: Often uses Phonetically Balanced (PB) or Consonant-Vowel-Nucleus-Consonant (CNC) word lists

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21. THE SPEECH AUDIOGRAM AND ROLLOVER

• Normal pattern: WRS increases as presentation level increases, reaching a plateau (PB-MAX)
• Rollover pattern: WRS peaks then decreases at higher presentation levels
• Rollover index = (PB-MAX - PB-Min) ÷ PB-Max
• If rollover index >0.45 = suggestive of retrocochlear pathology

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22. MOST COMFORTABLE LEVEL (MCL) & UNCOMFORTABLE LOUDNESS LEVEL (UCL)

• MCL (Most Comfortable Level): Intensity at which speech is most comfortably heard (~40-50 dB SL above SRT)
• UCL (Uncomfortable Loudness Level): Intensity at which sound is uncomfortably loud (~90-100 dB HL in normal ears)
• Dynamic Range = UCL - SRT: Normal = ~90 dB; Reduced in cochlear SNHL (loudness recruitment = UCL normal but SRT elevated → narrow dynamic range → important for hearing aid fitting)

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23. SPEECH AUDIOMETRY IN SITE-OF-LESION TESTING

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PART 6: THE COMPLETE TEST BATTERY - HOW IT ALL FITS TOGETHER

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KEY NUMBERS TO MEMORISE

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Pediatric Hearing Assessment - Complete Master Guide

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1. WHY PEDIATRIC HEARING ASSESSMENT IS DIFFERENT

• Developmental age (not just chronological age - always test to the child's developmental level)
• Cooperation and attention span
• Motor control (head turning, hand movements)

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2. EPIDEMIOLOGY & PREVALENCE

• Congenital permanent hearing loss (moderate-profound): ~1.1-1.6 per 1000 live births
• NICU infants: 2-4 per 1000 (nearly double general population)
• WHO estimate: 7.5 million children worldwide with clinically significant hearing loss
• Risk-factor-based targeted screening identifies only ~50% of affected infants - which is why universal screening is needed
• Late-onset/progressive PCHI adds to this: prevalence rises from ~0.91/1000 at age 3 to ~1.65/1000 at age 9

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3. THE 1-3-6 RULE (JCIH - Joint Committee on Infant Hearing)

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4. RISK FACTORS FOR PERMANENT CONGENITAL HEARING LOSS (JCIH)

1. Recessive genetic hearing loss (GJB2/connexin 26 mutations - most common genetic cause)
2. Congenital CMV infection

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5. AGE-APPROPRIATE HEARING TESTS - THE MASTER CHART

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STAGE 1: BIRTH TO 6 MONTHS - Newborn Hearing Screening (NHS)

Tools: OAE + AABR (Automated ABR)

• TEOAE: Click-evoked; broad frequency; detectable from ~30 weeks gestation
• DPOAE: More frequency-specific but less sensitive below 4 kHz
• Both give binary PASS/REFER result
• Fast, inexpensive, no patient cooperation needed
• Limitation: Misses auditory neuropathy; affected by middle ear fluid/debris

• Automated algorithm gives PASS/REFER based on Wave V detection
• Preferred in NICU infants - catches auditory neuropathy that OAE misses
• Slightly higher cost but lower false-positive rate than OAE

• Well babies: Two-stage - TEOAE first; if fail → AABR
• NICU/SCBU babies: TEOAE + AABR (both); AABR is primary
• Screen at least 12-24 hours after birth (to allow amniotic fluid to clear)
• False-positive rate: 1-2% (well below earlier 6-10%)

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STAGE 2: 0-6 MONTHS - Behavioural Observation (BOA)

• Moro reflex (startle) to loud sounds
• Auro-palpebral reflex (APR) - eye blink to sudden loud sound
• Cessation of activity (quieting)
• Arousal from sleep
• Eye widening, head turning (rudimentary)
• Changes in sucking pattern

• Does not give reliable thresholds - response depends on state, habituation
• Habituation occurs rapidly (only 2-3 responses obtainable)
• Minimum response levels (not thresholds): typically 40-70 dB (neonates), 30-50 dB (6 months)
• Cannot test each ear separately (free-field)
• Used to observe auditory behaviour only - not a screening or threshold test

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STAGE 3: 6-18 MONTHS - Distraction Test (Health Visitor Distraction Test - HVDT)

• Two examiners: one distracts child frontally, one presents sounds from the side at ~1 metre distance at ear level
• Sound presented at 35-40 dB (approximate conversation level)
• Stimuli: Manchester rattle (high frequency), voice "s" sound (high frequency), voice "oo" sound (low frequency)
• Positive response: head turn toward sound source
• Ear-specific testing not reliably possible

• Child must be able to sit up with some head control
• Must be alert/cooperative
• Age: ideally 7-8 months (before head turning declines)

• Poor sensitivity and specificity (UK abandoned it with UNHS introduction)
• Tester technique-dependent
• Habituation rapidly occurs
• Cannot give reliable frequency-specific thresholds

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STAGE 4: 6-24 MONTHS - Visual Reinforcement Audiometry (VRA)

1. Child sits on parent's lap between two speakers + visual reinforcers (at 90° left and right)
2. Conditioning phase: Pair sound + visual reward (toy lights up, animated display activates) several times to teach the association
3. Testing phase: Present sound alone; reward only correct head turns toward the stimulus ear
4. Start at easy levels to reinforce, then reduce intensity to find threshold
5. Threshold = lowest level with consistent correct localisation responses

• Sound field (speakers): Tests both ears together; cannot give ear-specific data
• Earphones/insert earphones: Gives ear-specific data (preferred)
• Bone conduction oscillator: Tests sensorineural component

• Child must sit unassisted with adequate head/neck control
• Must sustain attention for head turns
• Typically starts at ~6 months corrected age; optimal 6-24 months
• Some children can use VRA until 36 months

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STAGE 5: 2-5 YEARS - Conditioned Play Audiometry (CPA)

1. Establish the game: "Wait... listen... do it!" - demonstrate with hand-over-hand guiding
2. Once conditioned, present tones at different frequencies and intensities
3. Child completes the play action only when they hear the tone
4. Threshold = lowest level with consistent responses

• Frequencies tested: 250-8000 Hz (as tolerated)
• Gives ear-specific, frequency-specific thresholds
• Speech audiometry also possible: SAT (speech detection) or picture-pointing WRS tasks

• Motor response is more deliberate and reliable
• Less dependent on visual reinforcer novelty
• Can test more frequencies

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STAGE 6: ≥5 YEARS - Standard Pure Tone Audiometry (PTA)

• Adult technique from ~age 5, or earlier if child can cooperate
• All standard PTA procedures apply
• Normal hearing in children: ≤15 dB HL across frequencies
• Speech audiometry using picture-pointing and then words as appropriate

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6. OBJECTIVE TESTS - USED AT ANY AGE

Tympanometry in Children

• Standard probe tone: 226 Hz (children >6-7 months)
• Infants <6 months: 1000 Hz probe tone (external canal too compliant at 226 Hz → spuriously normal or flat results)
• Normal ECV in children: 0.3-0.9 mL
• Key use: Detecting OME (glue ear) - very common cause of conductive hearing loss in children
• Type B flat tympanogram = OME until proven otherwise
• Normal hearing in children ≤15 dB HL (not 20 dB like adults)

OAE in Children

• Can be performed at any age including neonates
• Requires intact middle ear (check tympanogram first)
• Used for: Newborn screening, monitoring ototoxicity, screening in school programs
• Present = OHCs functioning; Absent = OHC damage or middle ear problem

Diagnostic ABR in Children

• Done when behavioural testing is unreliable or when retrocochlear pathology suspected
• Requires sedation in infants and young children (natural sleep or chloral hydrate)
• Threshold ABR (tone-burst): Used to estimate frequency-specific hearing thresholds before behavioural testing is possible
• Wave V threshold correlates to PTA at 2000-4000 Hz (±10-15 dB)
• Click ABR for neurodiagnostic purposes (retrocochlear, ANSD)

ASSR (Auditory Steady State Response)

• Presents modulated tones; computer determines response statistically
• Frequency-specific (500, 1000, 2000, 4000 Hz separately)
• Objective thresholds in each ear across all speech frequencies
• Better than click-ABR for estimating low-frequency thresholds
• Used for: Infants with failed NHS, when tone-burst ABR thresholds are needed across all frequencies, hearing aid prescription in infants
• ASSR thresholds correlate well with behavioural audiogram

Acoustic Reflexes in Children

• Useful at any age
• In combination with tympanometry adds diagnostic value
• Absent reflexes + Type B tympanogram = strong evidence for OME

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7. NORMAL HEARING DEVELOPMENTAL MILESTONES

• No response to sound by 3 months
• No babbling by 12 months
• No single words by 16 months
• No 2-word phrases by 24 months
• Any loss of previously acquired language at any age

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8. UNIVERSAL NEWBORN HEARING SCREENING (UNHS) PROGRAMMES

US Programme (EHDI - Early Hearing Detection and Intervention)

• Goal: 1-3-6 rule (screen by 1 month, diagnose by 3 months, intervene by 6 months)
• Coverage: 98% of US newborns now screened before 1 month
• OAE (TEOAE/DPOAE) or AABR depending on nursery (well-baby vs NICU)

UK Programme (NHSP - Newborn Hearing Screening Programme)

• Well-baby protocol: TEOAE → if fail → AABR (two-stage, two-technology)
• NICU protocol: TEOAE + AABR (both performed); AABR is primary decision-maker
• Pass criteria: Pass in both ears at either stage
• Babies passing AABR but failing OAE in both ears = on CMV risk register (possible ANSD)

Screening result workflow:

PASS → Ongoing developmental surveillance (can develop later-onset loss)
REFER → Repeat screen → REFER again → Diagnostic audiological assessment by 3 months
         ↓
    Full battery: Diagnostic ABR, ASSR, OAE, tympanometry, ± tone-burst ABR

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9. CONGENITAL CMV - SPECIAL CONSIDERATION

• Most common non-genetic cause of congenital SNHL
• 90% of infected infants are asymptomatic at birth - yet still develop hearing loss
• SNHL from CMV can be progressive and late-onset - can pass newborn screen but develop loss later
• Up to 23% of asymptomatic congenital CMV infants develop SNHL
• Treatment: Valganciclovir (oral) for 6 months if symptomatic CMV with SNHL - improves hearing outcomes
• All infants failing newborn screen should be screened for cCMV within 3 weeks of birth (saliva PCR)

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10. AUDITORY NEUROPATHY SPECTRUM DISORDER (ANSD) IN CHILDREN

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11. COMPLETE PAEDIATRIC HEARING ASSESSMENT BATTERY

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12. KEY NUMBERS TO MEMORISE

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13. CROSS-CHECK PRINCIPLE (Jerger & Hayes, 1976)

• OAE + ABR + tympanometry + behavioural test should all agree
• When they disagree, investigate further
• Example: Child passes OAE but ABR absent → ANSD
• Example: Behavioural response present but OAE absent → may have OME (check tympanogram)

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Pediatric Hearing Assessment - Complete Master Guide

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1. WHY IT'S DIFFERENT FROM ADULT TESTING

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2. EPIDEMIOLOGY

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3. THE 1-3-6 RULE (JCIH - Joint Committee on Infant Hearing)

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4. RISK FACTORS FOR CONGENITAL HEARING LOSS (JCIH)

1. Recessive genetic hearing loss (GJB2/connexin 26 - most common overall genetic cause)
2. Congenital CMV infection

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5. AGE-APPROPRIATE TESTS - THE MASTER CHART

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STAGE 1: BIRTH → 6 MONTHS - Newborn Hearing Screening

Two tools: OAE and AABR

• TEOAE (click-evoked) - broadband; detectable from ~30 weeks gestation
• DPOAE - more frequency-specific but weaker below 4 kHz
• Result: binary PASS / REFER
• Fast, cheap, no cooperation needed
• Limitation: Misses auditory neuropathy; fails if middle ear has fluid/debris

• Automated algorithm detects Wave V → PASS/REFER
• Preferred for NICU infants - catches auditory neuropathy (ANSD) that OAE misses
• Slightly higher cost, lower false-positive rate than OAE
• Referral rate ~2-9% (AABR) vs 10-30% (TEOAE in suboptimal conditions)

• Screen at ≥12-24 hours after birth (allow amniotic fluid to clear → reduces false positives)
• False-positive rate now: 1-2% (was 6-10% early on)

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STAGE 2: 0-6 MONTHS - Behavioural Observation (BOA)

• Moro/startle reflex to sudden loud sound
• Auro-palpebral reflex (APR) - eye blink to loud sound
• Quieting / cessation of activity
• Arousal from sleep
• Eye widening, rudimentary head turn
• Changes in sucking pattern

• Does NOT give hearing thresholds - only shows auditory behaviour
• Rapid habituation (only 2-3 valid responses)
• Minimum response levels (not thresholds): ~40-70 dB neonates; 30-50 dB at 6 months
• Cannot test ears separately (sound field only)
• Not a screening test - used to observe global auditory development

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STAGE 3: 6-18 MONTHS - Distraction Test (HVDT)

• Two examiners needed
• Child sits on parent's lap, facing forward
• Distractor in front holds child's attention
• Tester presents sounds from 1 metre behind/to the side at ear level (45-90°)
• Sound level: ~35-40 dB (conversational)
• Stimuli: Manchester rattle (high-frequency), voiced "s" sound (high-frequency), "oo" sound (low-frequency)

• Tester technique-dependent, unreliable
• Cannot give frequency-specific thresholds
• Poor sensitivity and specificity
• UK abandoned with introduction of UNHS (poor sensitivity, high refer rate, not cost-effective)

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STAGE 4: 6-24 MONTHS - Visual Reinforcement Audiometry (VRA)

• Present sound + immediately activate visual reinforcer together
• Child learns the association: sound → turn head → see reward
• Several paired presentations until child turns reliably

• Present sound alone; reward correct head turns only
• Vary frequency and intensity to find threshold at each frequency
• Threshold = lowest level with consistent, reliable head-turn responses

• Child can sit unsupported
• Good head and neck control for head turns
• Reliable at ~6 months corrected age onward
• Works until ~24-36 months

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STAGE 5: 2-5 YEARS - Conditioned Play Audiometry (CPA / Play Audiometry)

• Dropping a ball into a bucket
• Placing a peg in a board
• Stacking rings on a peg
• Placing a block in a box

1. Hold the child's hand with toy ready
2. "Wait... listen..." (pause for silence)
3. Present tone → "Now!" → guide hand to complete task
4. Repeat until child responds independently
5. Begin threshold testing

• Ear-specific, frequency-specific thresholds (250-8000 Hz)
• Same type of result as adult PTA
• Both air and bone conduction possible
• Speech audiometry: SAT using picture-pointing; WRS with pictures

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STAGE 6: ≥5 YEARS - Standard Pure Tone Audiometry (PTA)

• Full adult technique from ~age 5 (or earlier if able)
• Normal = ≤15 dB HL in children
• All frequencies 250-8000 Hz
• Speech audiometry with picture-pointing at 2-3 years → word lists at school age

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6. OBJECTIVE TESTS - ANY AGE

Tympanometry in Children

• Normal ECV in children: 0.3-0.9 mL (adults 0.6-1.5 mL)
• Type B + normal ECV = OME (most common cause of conductive loss in children)
• Type B + large ECV = TM perforation or PE tube
• Normal hearing in children = ≤15 dB HL; OME typically causes flat 20-40 dB CHL

OAE in Children

• Any age including neonates
• Always check tympanogram first - middle ear effusion will suppress OAEs → false negative
• TEOAE for screening; DPOAE for ototoxicity/noise monitoring

Diagnostic ABR

• When behavioural testing unreliable (very young, developmental delay, suspected ANSD)
• Requires sedation in infants/toddlers (natural sleep, chloral hydrate, or GA)
• Threshold ABR (tone-burst): Frequency-specific threshold estimation
• Wave V threshold ≈ behavioural threshold ± 10-15 dB (at 2000-4000 Hz)
• Neurodiagnostic ABR: ANSD diagnosis, retrocochlear lesions

ASSR (Auditory Steady State Response)

• Modulated tones → computer determines response statistically (no subjectivity)
• Frequency-specific at 500, 1000, 2000, 4000 Hz per ear
• Better than click ABR for low-frequency thresholds
• Used for: Hearing aid fitting and prescription in infants before VRA is possible
• ASSR thresholds correlate well with behavioural PTA

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7. NORMAL AUDITORY DEVELOPMENTAL MILESTONES

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8. UNIVERSAL NEWBORN HEARING SCREENING (UNHS) - SCREENING FLOWCHART

ALL NEWBORNS
     ↓
OAE / AABR (by 1 month)
     ↓              ↓
   PASS            REFER
     ↓              ↓
Ongoing           Repeat screen
surveillance      (allow amniotic fluid to clear if early)
                       ↓
                   REFER again
                       ↓
              Full diagnostic assessment
              (by 3 months):
              ABR + ASSR + OAE + Tympanometry
              ± Genetic testing
              ± CMV testing (within 3 weeks of birth)
                       ↓
              INTERVENTION by 6 months
              (hearing aids / cochlear implant referral / AVPT)

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9. AUDITORY NEUROPATHY SPECTRUM DISORDER (ANSD)

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10. CONGENITAL CMV - KEY POINTS

• Most common non-genetic cause of congenital SNHL
• 90% of infected infants are asymptomatic at birth but still develop SNHL
• Hearing loss from CMV can be late-onset and progressive - passes newborn screen but develops loss later → need ongoing surveillance
• Diagnosis: Saliva/urine CMV PCR within first 3 weeks of life
• Treatment: Valganciclovir oral for 6 months in symptomatic infants → improves hearing and neurodevelopmental outcomes

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11. COMPLETE TEST SELECTION BY AGE - QUICK REFERENCE

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12. KEY NUMBERS TO MEMORISE

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