What is the recommended initial diagnostic test for assessing hearing sensitivity in individuals suspected of having hearing loss, specifically using pure tone audiometry (PTA)?

Pure Tone Audiometry: The Gold Standard for Diagnosing Hearing Loss

Pure tone audiometry (PTA) is the gold standard diagnostic test for assessing hearing sensitivity in individuals suspected of having hearing loss and should be the initial test performed. 1

Components of Comprehensive Audiometric Evaluation

A comprehensive diagnostic evaluation for hearing loss should include:

• Pure tone thresholds: Measures hearing sensitivity through both air conduction and bone conduction pathways 1, 2

  • Air and bone conduction thresholds should be measured at frequencies from 250-8000 Hz 1, 2
  • Mid-octave frequencies (750,1500,3000,6000 Hz) should be tested if differences between adjacent octave frequencies are ≥20 dB 1

• Speech audiometry: Assesses functional hearing ability 1

  • Speech recognition threshold (SRT) or speech detection threshold 1
  • Word recognition scores (WRS) measured at suprathreshold levels 1

• Tympanometry: Evaluates middle ear function 1, 2

• Acoustic reflex testing: Assesses neural pathways 1, 2

Clinical Value of Pure Tone Audiometry

PTA provides critical diagnostic information that guides treatment decisions:

• Establishes the pattern of hearing loss at various frequencies 1, 3
• Differentiates the degree of hearing loss (mild, moderate, severe, or profound) 1, 4
• Determines the configuration/type of hearing loss (sensorineural, conductive, or mixed) 1, 2
• Provides baseline measurements for monitoring changes over time 1
• Enables appropriate treatment planning based on specific hearing deficits 1, 3

Interpretation of Results

• Normal hearing is typically defined as thresholds ≤20 dB HL 2, 4
• Asymmetric hearing loss (difference in PTA between ears of >15 dB or >15% difference in word recognition scores) requires further evaluation 1
• Pure tone average (PTA) typically includes frequencies of 500,1000, and 2000 Hz, but including 4000 Hz (PTA4) provides better correlation with functional hearing 4, 5
• High-frequency PTA (4000,6000,8000 Hz) has higher sensitivity for detecting early hearing loss 4

Limitations and Considerations

• Access to audiometric testing may be limited in some regions (56.6% of US counties lack access to audiologists) 1
• Older adults may have difficulty completing testing due to cognitive dysfunction 1
• Standard test-retest variability typically fluctuates by ±5 dB across frequencies 1
• Testing variations can influence results (different transducers and their placement) 1, 6

Alternative Screening Methods

When comprehensive audiometry is not immediately available:

• Automated audiometry can be considered as a secondary alternative 1
• App-based or online testing options exist but have moderate evidence quality compared to standard PTA 1
• Self-reported hearing assessment using validated questions has reasonable accuracy at a population level but cannot substitute for audiometry 7

Special Considerations

• For asymmetric hearing loss, conductive/mixed hearing loss, or poor word recognition, referral to an otolaryngologist is recommended 1
• Baseline audiometry should be performed before treatment with potentially ototoxic medications 2
• Age-appropriate testing methods should be selected for pediatric populations 2

Pure tone audiometry remains the cornerstone of hearing assessment, providing essential information about the type, degree, and configuration of hearing loss that guides appropriate intervention and treatment planning.