How should I interpret an audiology report for hearing loss?

How to Interpret an Audiology Report for Hearing Loss

An audiology report should be interpreted systematically by first identifying the type of hearing loss (conductive, sensorineural, or mixed) through comparison of air and bone conduction thresholds, then quantifying the degree of loss using pure-tone averages, and finally assessing the functional impact through speech audiometry and configuration patterns. 1

Step 1: Understand the Core Components

Every comprehensive audiology report contains several key elements that must be reviewed sequentially:

• Pure-tone audiometry measures hearing thresholds at specific frequencies (250-8000 Hz) through both air conduction (via headphones) and bone conduction (via skull vibration), providing the foundation for diagnosis 1, 2
• Speech audiometry assesses functional hearing ability through speech recognition threshold (SRT) and word recognition scores (WRS), which predict real-world communication ability 1
• Tympanometry evaluates middle ear function and identifies conditions like effusion or perforation that cause conductive hearing loss 1, 3

Step 2: Identify the Type of Hearing Loss

The relationship between air and bone conduction thresholds determines the type:

• Sensorineural hearing loss: Air and bone conduction thresholds are both elevated and overlap (within 10 dB of each other), indicating inner ear or auditory nerve damage 2, 1
• Conductive hearing loss: Bone conduction thresholds are normal (≤20 dB HL) but air conduction thresholds are elevated, with an "air-bone gap" of ≥15 dB, indicating middle ear or external ear pathology 2, 1
• Mixed hearing loss: Both air and bone conduction thresholds are elevated, but an air-bone gap persists, indicating combined pathology 2

Critical pitfall: Always distinguish between these types because treatment differs fundamentally—conductive losses may be surgically correctable while sensorineural losses typically require amplification. 4

Step 3: Quantify the Degree of Hearing Loss

Calculate the pure-tone average (PTA) at 500,1000, and 2000 Hz for each ear:

• Normal hearing: ≤20 dB HL (≤15 dB HL in children) 1, 2
• Slight hearing loss: 16-25 dB HL 2
• Mild hearing loss: 26-40 dB HL 2
• Moderate hearing loss: 41-55 dB HL 2, 1
• Moderately severe hearing loss: 56-70 dB HL 2, 1
• Severe hearing loss: 71-90 dB HL 2, 1
• Profound hearing loss: ≥91 dB HL 2, 1

Important caveat: Standard test-retest variability is ±5 dB, so changes <10 dB between tests may not represent true threshold shifts. 1

Step 4: Assess Configuration and Laterality

The pattern of hearing loss across frequencies provides diagnostic clues:

• Sloping configuration (high-frequency loss): Most consistent with age-related hearing loss (presbycusis) or noise exposure 2, 1
• Flat configuration (equal loss across frequencies): Suggests genetic causes or certain ototoxic medications 2
• Rising configuration (low-frequency loss): May indicate Ménière's disease or certain genetic syndromes 2
• Cookie-bite configuration (mid-frequency loss): Often hereditary 2

Critical red flag: Asymmetric hearing loss (≥10 dB difference at 2+ contiguous frequencies OR ≥15 dB at any single frequency) requires urgent evaluation for retrocochlear pathology like vestibular schwannoma, even if thresholds are near-normal. 2, 1 MRI of internal auditory canals is mandatory. 1

Step 5: Evaluate Speech Audiometry Results

Speech testing provides functional information that pure-tone thresholds cannot:

• Speech Recognition Threshold (SRT) should correlate within ±5-12 dB of the pure-tone average at 500,1000, and 2000 Hz 1, 5
• Word Recognition Scores (WRS) at comfortable listening levels indicate how well the patient will understand speech with amplification 1
• Poor WRS (<50%) despite mild-moderate hearing loss suggests retrocochlear pathology or severe cochlear damage and warrants otolaryngology referral 1, 6

Common pitfall: The pure-tone audiogram alone does not predict functional hearing ability—patients with identical audiograms may have vastly different speech understanding due to cochlear damage patterns. 6, 7

Step 6: Review Tympanometry Results

Tympanometry classifies middle ear status:

• Type A (normal peak at 0 daPa): Normal middle ear function 3
• Type B (flat, no peak): Middle ear effusion or tympanic membrane perforation—expect conductive hearing loss 3
• Type C (peak at negative pressure): Eustachian tube dysfunction 3

Important note: Tympanometry assesses middle ear status but does NOT measure hearing—normal tympanometry does not exclude sensorineural hearing loss. 2, 3

Step 7: Consider Age-Specific Factors

Interpretation varies by patient age:

• Children under 3 years: "Normal" thresholds may be up to 15 dB higher than older children due to developmental and testing methodology limitations 1
• Children with recurrent otitis media: Conductive hearing loss from middle ear effusion is common and requires comprehensive audiometry, not just screening 3
• Adults over 50 years: High-frequency hearing loss (4000-8000 Hz) is expected with aging, but asymmetry or rapid progression warrants investigation 1, 8

Step 8: Identify Urgent Referral Situations

Certain findings require immediate action:

• Sudden sensorineural hearing loss (≥30 dB loss within 72 hours): Otolaryngology referral within 24-48 hours for possible corticosteroid treatment 4
• Asymmetric sensorineural hearing loss: MRI to exclude vestibular schwannoma 2, 1
• Unilateral hearing loss with asymmetric tinnitus: 5.4% harbor vestibular schwannoma 2
• Conductive hearing loss not explained by cerumen or effusion: Otolaryngology evaluation for ossicular pathology 4

Special Considerations for Ototoxicity Monitoring

When monitoring patients on cisplatin, aminoglycosides, or other ototoxic medications:

• Baseline audiometry must be obtained before treatment initiation 2, 1
• Serial monitoring should occur before each dose and after treatment completion 2, 1
• Chang Grading System (grades 0-4) is more clinically useful than CTCAE criteria for pediatric cisplatin ototoxicity, as it captures functionally significant high-frequency losses 2
• High-frequency testing (6000-8000 Hz) detects ototoxicity earlier than speech-frequency testing 2

Critical caveat: Distinguish sensorineural ototoxicity from conductive hearing loss due to middle ear effusion in immunosuppressed patients—only sensorineural changes represent true ototoxicity. 2

Functional Impact Assessment

Beyond the numbers, consider real-world implications:

• Hearing loss >25 dB HL in children impairs language acquisition and academic performance, particularly in noisy classroom environments 2
• Bilateral hearing loss >30 dB HL in the better ear significantly impacts binaural processing and sound localization 2
• Speech-frequency hearing loss (500-4000 Hz) has greater functional impact than isolated high-frequency loss 1

Key principle: The audiogram measures hearing sensitivity only—it does not assess central auditory processing, speech understanding in noise, or real-world communication ability, which require additional testing. 7