Hearing Handicap Percentage Calculator
Hearing Handicap Percentage Calculator
Binaural hearing impairment as a percentage by the AAO-HNS and AMA method — a 25 dB fence, 1.5% per decibel, and the better ear weighted five to one. An arithmetic percentage under one named scheme, not a disability rating.
Binaural hearing impairment
AAO-HNS and AMA methodRight ear four-frequency PTA 55 dB HL, left ear 30 dB HL, both over 500, 1000, 2000 and 3000 Hz
Formula
- the frequency set
- 500, 1000, 2000 and 3000 Hz, each ear separately. Minnesota Rules 5223.0340 subp. 4 directs the examiner to “test the hearing threshold levels at the four frequencies of 500, 1,000, 2,000, and 3,000 Hertz” and take “one-fourth of the sum”. 3000 Hz was added in the 1979 revision, replacing a three-frequency average, to reflect speech understanding in noise as well as in quiet
- 25, the low fence
- “subtract 25 decibels from the average four-frequency hearing level”. Below the fence the method returns zero: a four-frequency average of 24 dB is 0% impairment under this scheme even though it is not normal hearing under WHO’s 20 dB limit. The 1959 version of the method used a 15 dB fence over three frequencies, so a percentage computed then is not comparable with one computed now
- 1.5, the slope
- “multiply the adjusted average four-frequency hearing level by 1.5” — 1.5 per cent per decibel above the fence. It is linear by construction, and Dobie found the relationship between the better-ear average and self-reported performance to be roughly linear above 25 dB HL, which is the empirical basis for the shape
- 0 to 100, the clamp
- “a product greater than 100 percent is deemed to be 100 percent” and a negative product is set to zero. The arithmetic reaches 100% at 25 + 100/1.5 = 91.67 dB; the method’s stated high fence is 92 dB HL
- 5, the better-ear weight
- “multiply the monaural hearing loss of the better ear by five”, add the poorer ear’s monaural loss, “divide the sum by six”. The better ear is the one with the smaller monaural percentage. One deaf ear and one normal ear therefore gives 100 ÷ 6 = 16.7%, which is the figure that draws most of the criticism of the method and is also its deliberate design
- what this is NOT
- a disability rating, a whole-person impairment, a compensation award or a diagnosis. The AMA Guides convert binaural impairment to whole-person impairment through a separate copyrighted table, which is not reproduced or approximated here, and jurisdictions vary the fence, the frequency set, the weighting and the deductions
- licensing, since the question comes up
- the arithmetic above is quoted from published state regulations — Minnesota Rules 5223.0340 and Washington L&I form F252-007-000 — which are public legal texts carrying the formula in full. That is why this method is here and the licensed self-report instruments in this field (the APHAB, which its own authors state may not legally be copied or adapted by anyone else) are not
Worked example
Right ear four-frequency PTA 55 dB HL, left ear 30 dB HL, both over 500, 1000, 2000 and 3000 Hz
Right ear: (55 − 25) × 1.5 = 30 × 1.5 = 45.0% monaural
Left ear: (30 − 25) × 1.5 = 5 × 1.5 = 7.5% monaural
The better ear is the one with the smaller monaural percentage, so the left ear at 7.5% is the better ear
Binaural = (5 × 7.5 + 45.0) ÷ 6 = (37.5 + 45.0) ÷ 6 = 82.5 ÷ 6 = 13.8% binaural impairment
The weighting is the whole story. The unweighted mean of 45.0 and 7.5 is 26.25%, so the 5:1 weighting pulls the answer down by 12.5 percentage points. Weight the WORSE ear five times instead and the same ears give 38.8% — nearly three times the published answer, which is why the orientation has to be right and why a check on two equal ears could never catch it
The order of entry does not matter. Enter 30 on the right and 55 on the left and the answer is still 13.8%, because the method picks the better ear by its percentage rather than by its side
Both clamps. An ear at 10 dB HL gives 0% rather than a negative figure; an ear at 120 dB HL gives 100% rather than 142.5%. The arithmetic crosses 100% at 91.67 dB, and 91 dB gives 99.0%
The case that defines the method. One ear at 25 dB (0%) and one totally deaf (100%) gives (5 × 0 + 100) ÷ 6 = 16.7%. Single-sided deafness is 16.7% binaural impairment under this scheme — a figure that is either the method working as designed or its central flaw, depending on who is reading it
Equal ears collapse onto the monaural value. 55 dB in both ears gives 45.0% binaural, the same as either ear alone. That is the degenerate case, and it is the one point where a transposed weighting would agree with the correct one
The method, step by step, with the numbers that are specified
| Step | What the rule says | Value |
|---|---|---|
| Average each ear | “the four frequencies of 500, 1,000, 2,000, and 3,000 Hertz”; “one-fourth of the sum” | 4 frequencies |
| Subtract the fence | “subtract 25 decibels from the average four-frequency hearing level” | 25 dB |
| Multiply | “multiply the adjusted average four-frequency hearing level by 1.5” | 1.5% per dB |
| Limit | “a product greater than 100 percent is deemed to be 100 percent”; a negative product is zero | 0 to 100% |
| Combine | “multiply the monaural hearing loss of the better ear by five”, add the poorer ear, “divide the sum by six” | 5:1 |
What the better-ear weighting does
| Right ear PTA | Left ear PTA | Monaural % | Binaural % (5:1) | Unweighted mean % |
|---|---|---|---|---|
| 25 | 25 | 0.0 and 0.0 | 0.0 | 0.0 |
| 55 | 30 | 45.0 and 7.5 | 13.8 | 26.3 |
| 55 | 55 | 45.0 and 45.0 | 45.0 | 45.0 |
| 92 | 25 | 100.0 and 0.0 | 16.7 | 50.0 |
| 92 | 92 | 100.0 and 100.0 | 100.0 | 100.0 |
| 70 | 40 | 67.5 and 22.5 | 30.0 | 45.0 |
One scheme’s arithmetic, and what it deliberately does not measure
The AAO-HNS and AMA method turns two audiograms into a single percentage in four steps. Average each ear over 500, 1000, 2000 and 3000 Hz. Subtract a 25 dB fence, on the premise that hearing better than that does not produce a measurable handicap for everyday speech. Multiply the remainder by 1.5 to get a monaural percentage, capped at 100. Then combine the ears with the better one weighted five times. It is the most widely codified hearing impairment formula there is: it is written out verbatim in US state compensation rules, which is both why it can be reproduced here and why it is worth knowing exactly.
Three of those four numbers are contestable and all three have been contested. The fence has moved: the 1959 version used 15 dB over three frequencies, the 1979 revision moved to 25 dB over four, and WHO now puts the limit of normal hearing at 20 dB, so a four-frequency average of 24 dB is 0% impairment under this method and a hearing loss under WHO’s grades. The frequency set is not WHO’s: this method takes 3000 Hz and not 4000 Hz, which systematically understates a noise notch relative to the WHO average on the same ear. And the 5:1 weighting means single-sided deafness scores 16.7%, a figure that strikes many readers as obviously too low.
The weighting is nevertheless the part with the most empirical support. Dobie’s analysis of more than a thousand patients at five audiology centres, using a self-report measure of communication performance, found that reported performance tracked better-ear thresholds more closely than worse-ear thresholds, tracked pure tone averages more closely than word recognition scores, and that weights anywhere between 3:1 and 9:1 performed about equally. No alternative pure tone average outperformed this one. The conclusion was that nothing obvious would improve the method’s accuracy for its medico-legal purpose.
What the percentage is not is a disability. It is a scheme-specific arithmetic summary of two averaged thresholds. It takes no account of tinnitus, of speech understanding in noise, of the listening demands of a particular job, of the age of the person or of any cause. Converting it to a whole-person impairment is a separate step in a separate published table, which this page does not reproduce, and jurisdictions differ in fence, frequency set, weighting and deductions. Audiometric results are equipment- and calibration-dependent: the dB HL scale is defined against the reference equivalent threshold levels of the ISO 389 series for a particular transducer and coupler, so the same ear can read differently on two audiometers, and the BSA recommended procedure puts the uncertainty of any threshold measurement at no better than plus or minus 5 dB. Your own audiogram and the calibration standard it was recorded against govern, not this arithmetic. This page computes the number and names the body that publishes the thresholds. It does not decide anything: the grades, action values and criteria quoted here are scheme- and jurisdiction-specific, and whether any of them is met in a particular case, and what should follow, is for the clinician, the audiologist or the responsible person under the applicable regulation to determine.
Frequently asked questions
How is percentage hearing impairment calculated?
Average each ear’s thresholds at 500, 1000, 2000 and 3000 Hz, subtract a 25 dB fence, multiply by 1.5 and cap at 0–100% for each ear, then combine them as (5 × better ear + worse ear) ÷ 6. Right 55 dB and left 30 dB gives 45.0% and 7.5% monaural and 13.8% binaural.
Why is the better ear weighted five times?
Because self-reported communication performance follows the better ear much more closely than the worse one. Dobie’s analysis of over a thousand patients at five centres found exactly that, and that better-to-worse weights from 3:1 to 9:1 all performed about equally — so the 5:1 figure is a convention inside a range the data support rather than a measured constant.
What percentage impairment is single-sided deafness?
16.7% under this method: (5 × 0 + 100) ÷ 6. That is a sixth of the deaf ear and nothing else, and it is the result most often cited against the formula — it makes no allowance for the loss of binaural hearing, sound localisation or speech in noise, all of which single-sided deafness affects.
Which frequencies does this use, and why not 4000 Hz?
500, 1000, 2000 and 3000 Hz. The 1979 revision added 3000 Hz to a previous three-frequency average to better reflect speech understanding in noise. Because it stops at 3000 Hz it understates a 4000 Hz noise notch relative to WHO’s four-frequency average on the same ear.
Is 0% impairment the same as normal hearing?
No. The 25 dB fence means a four-frequency average anywhere up to 25 dB returns 0%, while WHO puts the limit of normal hearing at 20 dB. An ear at 24 dB has no impairment under this scheme and a mild hearing loss under the 2021 WHO grades.
Related calculators
References
- Minnesota Rules 5223.0340, Hearing loss, subpart 4. Minnesota Revisor of Statutes.
- Washington State Department of Labor and Industries. Hearing loss worksheet, form F252-007-000. Olympia, WA: L&I.
- Staab W. The AMA method of estimation of hearing disability — validation. Hearing Health & Technology Matters (Wayne’s World), 2011. Reporting Dobie RA’s analysis of more than 1,000 patients at five centres.
- American Academy of Audiology. Pure tone average and speech in noise. Reston, VA: AAA.
Not medical advice. For healthcare professionals and education. Reference intervals vary by laboratory and assay — always use your own laboratory's. Never base a dose or a treatment decision on this page alone. Full disclaimer at calcengines.com/disclaimer/