At what decibel levels and ages are pure tone thresholds considered pass, equivocal, or refer?

Pure Tone Threshold Screening Criteria

For hearing screening purposes, pure tone thresholds ≤20 dB HL are considered pass/normal across all ages, while thresholds >20 dB HL at any frequency warrant referral for comprehensive audiologic evaluation. 1, 2

Standard Screening Thresholds by Age

Children (Ages 2-4 Years)

• Pass: Air-conduction thresholds ≤20 dB HL at all tested frequencies 2
• Refer: Thresholds >20 dB HL at any frequency indicate possible hearing loss and require referral to a pediatric audiologist 2
• Testing method: Play audiometry is the appropriate screening technique for this age group 2

School-Age Children and Adults

• Normal hearing: ≤20 dB HL (general standard) 1
• Alternative adult threshold: Pure-tone average ≤15 dB HL at 500,1000, and 2000 Hz represents optimal normal hearing 3
• Clinical significance threshold: The 15-30 dB range is functionally meaningful, as individuals in this range demonstrate significantly poorer cognitive, language, and reading skills compared to those with better hearing 3

Diagnostic Classification Beyond Screening

Degree of Hearing Loss (Diagnostic Audiometry)

Once referred for comprehensive evaluation, hearing loss is classified as:

• Normal: ≤20 dB HL 1
• Mild: 21-40 dB HL
• Moderate: 41-55 dB HL
• Moderately severe: 56-70 dB HL
• Severe: 71-90 dB HL
• Profound: >90 dB HL

Serviceable vs. Non-Serviceable Hearing

The American Academy of Otolaryngology-Head and Neck Surgery classifies functional hearing status for rehabilitation purposes 1:

• Class B (Serviceable): PTA 31-50 dB with discrimination 50-69% 1
• Class C (Serviceable): PTA >50 dB with discrimination 50-69% 1
• Both classifications indicate usable hearing appropriate for hearing aid amplification 1

Age-Specific Testing Considerations

Infants (<6 Months)

• Use auditory brainstem response (ABR) or otoacoustic emissions (OAEs) rather than pure tone audiometry 1

Young Children (6 Months to 2 Years)

• Visual reinforcement audiometry is the appropriate method 1

Preschool Children (2-4 Years)

• Play audiometry is recommended 1, 2

Children 4+ Years and Adults

• Conventional pure tone audiometry can be performed 1

Critical Clinical Caveats

Asymmetric Hearing Loss

• Any asymmetry ≥15 dB HL at 2 or more frequencies between ears warrants MRI evaluation to exclude retrocochlear pathology such as vestibular schwannoma 3
• Unilateral high-frequency loss is never consistent with normal age-related changes and requires investigation 3

Middle Ear Considerations

• Do not rely on pure tone screening alone in children with recurrent ear infections – concurrent tympanometry is essential to identify middle ear effusion 2
• Air-conduction thresholds >20 dB may reflect conductive hearing loss from middle ear effusion rather than sensorineural hearing loss 2
• Type B (flat) tympanograms indicate high probability of middle ear effusion causing conductive hearing loss 2

Common Screening Pitfalls

• Do not assume normal hearing based solely on newborn screening – acquired hearing loss from recurrent otitis media is common and would not have been detected at birth 2
• Standard test-retest variability typically fluctuates by ±5 dB across frequencies, so changes <10 dB may not represent true threshold shifts 4
• Do not delay hearing assessment waiting for infections to resolve – this may miss critical periods for speech and language development if hearing loss is present 2

Monitoring Ototoxicity

For children receiving cisplatin or other ototoxic medications, baseline audiometry should be performed before treatment with serial monitoring during and after treatment 4, 1