What is the normal range of high-frequency hearing loss by age 48?

Normal High-Frequency Hearing Loss at Age 48

At age 48, some degree of high-frequency hearing loss (above 8 kHz) is common and can be considered within normal age-related variation, though conventional audiometry (up to 8 kHz) should still show thresholds ≤25 dB HL to be classified as "normal hearing."

Expected Hearing Thresholds by Age 48

Conventional Frequencies (≤8 kHz)

• Normal hearing is defined as pure-tone average ≤15 dB HL at 500,1000, and 2000 Hz for adults 1
• At age 48, individuals should maintain thresholds ≤25 dB HL across conventional audiometric frequencies (500-8000 Hz) to be considered within normal limits 2
• The prevalence of speech-frequency hearing impairment (>25 dB HL) increases substantially with age, reaching approximately 39.3% by ages 60-69 years 2

Extended High Frequencies (>8 kHz)

• High-frequency hearing loss above 8 kHz is extremely common even in "normally hearing" adults well before age 48 3
• In a study of predominantly younger adults with normal conventional audiometry, 74 of 116 (64%) already demonstrated hearing loss at frequencies above 8 kHz 3
• Extended high-frequency thresholds in older listeners (60-79 years) are substantially elevated compared to younger listeners, even when conventional audiometry remains normal 4

Clinical Significance of High-Frequency Loss

Impact on Function

• Extended high-frequency hearing (8-20 kHz) contributes meaningfully to speech perception in noise, even though clinical audiometry stops at 8 kHz 3
• Individuals with extended high-frequency hearing loss report significantly more difficulty hearing in noisy environments, despite having "normal" conventional audiograms 3
• The 15-30 dB threshold range is clinically meaningful because children (and by extension adults) with hearing in this range demonstrate significantly poorer cognitive, language, and reading skills compared to those with better hearing 1, 5

Pattern Recognition

• Age-related hearing loss characteristically begins with high-frequency loss due to basal cochlear hair cell degeneration, then progressively affects mid-range and lower frequencies 6
• Normal age-related hearing loss should be bilateral and symmetric; any asymmetry (≥15 dB HL at 2 or more frequencies, or ≥15 dB HL at any 2 frequencies between 2000-8000 Hz) warrants further evaluation for retrocochlear pathology 1

Key Clinical Caveats

What Requires Further Workup at Age 48

• Asymmetric hearing loss (>15 dB difference between ears at high frequencies) necessitates MRI of internal auditory canals to exclude vestibular schwannoma or meningioma 1
• Unilateral high-frequency loss is not consistent with normal age-related changes and requires investigation 6
• Rapidly progressive high-frequency loss over months rather than years suggests pathology beyond presbycusis 6

Noise Exposure Considerations

• Heavy firearm use (≥1000 rounds fired) and occupational/recreational loud noise exposure significantly accelerate high-frequency hearing loss beyond normal age-related changes 2
• Male sex, non-Hispanic white or Asian race/ethnicity, and lower educational level are additional risk factors for earlier and more severe high-frequency hearing loss 2

Practical Threshold Expectations

• At age 48, thresholds at 4000 Hz should remain ≤25 dB HL for normal hearing 2
• At 8000 Hz, some elevation (up to 30-35 dB HL) may represent early age-related changes, particularly with noise exposure history 2, 4
• Beyond 8000 Hz, measurable hearing loss is common even in younger adults and should not be considered pathologic unless asymmetric or associated with other concerning features 3, 4