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Pure-tone average and hearing loss grade (WHO 2021)

Calculates each ear’s air-conduction pure-tone averages and grades hearing loss using the better ear, according to WHO (2021).

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Check the population, units and version. The result shows the formula or classification; it does not make an automatic treatment decision.

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Method · Limits of application

WHO 2021 World Report on Hearing: PTA 4 frequencies 500/1000/2000/4000, better ear; PTA 3 separate

The WHO 2021 classification here uses the average of 500, 1000, 2000 and 4000 Hz in the better ear and its adult grades; the three-frequency average displayed separately must not be confused with this method. Thresholds must come from appropriate audiometry and use dB HL, also called dB NA. The numerical grade alone does not describe communication ability, context or rehabilitation needs; WHO itself highlights this limitation. Unilateral hearing loss and pediatric application require specific interpretation and must not be assumed from the adult total.

Conditions of use

Check the population, units, inclusion and exclusion criteria, and version in the original source. A result alone does not establish a diagnosis, discharge decision or prescription.

Documented parameters

Right ear · 500 Hz · dB HL
Right ear · 1,000 Hz · dB HL
Right ear · 2,000 Hz · dB HL
Right ear · 4,000 Hz · dB HL
Left ear · 500 Hz · dB HL
Left ear · 1,000 Hz · dB HL
Left ear · 2,000 Hz · dB HL
Left ear · 4,000 Hz · dB HL

5/5 reference cases checked. Numerical tests are not clinical validation.

Sources and documentation

Documented formula

Transcribed from the source or a recorded revision; this is not a clinical recommendation.

Four-frequency average (WHO) = mean air-conduction thresholds at 500, 1,000, 2,000 and 4,000 Hz. Three-frequency average = mean at 500, 1,000 and 2,000 Hz (used in traditional classifications, such as Lloyd and Kaplan).

The WHO grade uses the four-frequency average of the better ear.

References

Identifier: grau-de-perda-auditiva

Original clinical content: Brazilian Portuguese.

Method version

WHO 2021 World Report on Hearing: PTA 4 frequencies 500/1000/2000/4000, better ear; PTA 3 separate

grau-de-perda-auditiva@native-2026-10-03+978f75033f6c

Source for the active edition

The bibliographic edition identifies the source. By itself, it proves neither full conformity of the formula nor clinical approval.

Synthetic cases checked (5)

Synthetic cases for checking the implementation, with no patient data.

Case 1

reference-001

Inputs

Right ear · 500 Hz: 20 dB HL
Right ear · 1,000 Hz: 25 dB HL
Right ear · 2,000 Hz: 30 dB HL
Right ear · 4,000 Hz: 35 dB HL
Left ear · 500 Hz: 30 dB HL
Left ear · 1,000 Hz: 35 dB HL
Left ear · 2,000 Hz: 40 dB HL
Left ear · 4,000 Hz: 45 dB HL

{
  "od500": 20,
  "od1k": 25,
  "od2k": 30,
  "od4k": 35,
  "oe500": 30,
  "oe1k": 35,
  "oe2k": 40,
  "oe4k": 45
}

Expected result

{
  "od": 27.5,
  "oe": 37.5,
  "melhor": 27.5,
  "tri_od": 25
}

Actual result

{
  "od": 27.5,
  "oe": 37.5,
  "melhor": 27.5,
  "tri_od": 25,
  "tri_oe": 35,
  "unilateral": 0
}

Case 2

reference-002

Inputs

Right ear · 500 Hz: 10 dB HL
Right ear · 1,000 Hz: 10 dB HL
Right ear · 2,000 Hz: 10 dB HL
Right ear · 4,000 Hz: 10 dB HL
Left ear · 500 Hz: 10 dB HL
Left ear · 1,000 Hz: 10 dB HL
Left ear · 2,000 Hz: 10 dB HL
Left ear · 4,000 Hz: 10 dB HL

{
  "od500": 10,
  "od1k": 10,
  "od2k": 10,
  "od4k": 10,
  "oe500": 10,
  "oe1k": 10,
  "oe2k": 10,
  "oe4k": 10
}

Expected result

{
  "melhor": 10
}

Actual result

{
  "od": 10,
  "oe": 10,
  "melhor": 10,
  "tri_od": 10,
  "tri_oe": 10,
  "unilateral": 0
}

Case 3

reference-003

Inputs

Right ear · 500 Hz: 10 dB HL
Right ear · 1,000 Hz: 10 dB HL
Right ear · 2,000 Hz: 15 dB HL
Right ear · 4,000 Hz: 20 dB HL
Left ear · 500 Hz: 40 dB HL
Left ear · 1,000 Hz: 45 dB HL
Left ear · 2,000 Hz: 50 dB HL
Left ear · 4,000 Hz: 60 dB HL

{
  "od500": 10,
  "od1k": 10,
  "od2k": 15,
  "od4k": 20,
  "oe500": 40,
  "oe1k": 45,
  "oe2k": 50,
  "oe4k": 60
}

Expected result

{
  "od": 13.75,
  "oe": 48.75,
  "unilateral": 1
}

Actual result

{
  "od": 13.75,
  "oe": 48.75,
  "melhor": 13.75,
  "tri_od": 11.666666666666666,
  "tri_oe": 45,
  "unilateral": 1
}

Case 4

reference-004

Inputs

Right ear · 500 Hz: 70 dB HL
Right ear · 1,000 Hz: 75 dB HL
Right ear · 2,000 Hz: 80 dB HL
Right ear · 4,000 Hz: 85 dB HL
Left ear · 500 Hz: 80 dB HL
Left ear · 1,000 Hz: 85 dB HL
Left ear · 2,000 Hz: 90 dB HL
Left ear · 4,000 Hz: 95 dB HL

{
  "od500": 70,
  "od1k": 75,
  "od2k": 80,
  "od4k": 85,
  "oe500": 80,
  "oe1k": 85,
  "oe2k": 90,
  "oe4k": 95
}

Expected result

{
  "melhor": 77.5,
  "tri_od": 75
}

Actual result

{
  "od": 77.5,
  "oe": 87.5,
  "melhor": 77.5,
  "tri_od": 75,
  "tri_oe": 85,
  "unilateral": 0
}

Case 5

reference-005

Inputs

Right ear · 500 Hz: 35 dB HL
Right ear · 1,000 Hz: 35 dB HL
Right ear · 2,000 Hz: 35 dB HL
Right ear · 4,000 Hz: 35 dB HL
Left ear · 500 Hz: 40 dB HL
Left ear · 1,000 Hz: 40 dB HL
Left ear · 2,000 Hz: 40 dB HL
Left ear · 4,000 Hz: 40 dB HL

{
  "od500": 35,
  "od1k": 35,
  "od2k": 35,
  "od4k": 35,
  "oe500": 40,
  "oe1k": 40,
  "oe2k": 40,
  "oe4k": 40
}

Expected result

{
  "melhor": 35
}

Actual result

{
  "od": 35,
  "oe": 40,
  "melhor": 35,
  "tri_od": 35,
  "tri_oe": 40,
  "unilateral": 0
}

Code and reproducibility

This tool’s code on GitHub

Download code and tests

Sources, version and reproduction instructions

The code tests are technical checks. Clinical approval and professional translation review are recorded separately.

Relationship with cancer research

General context — relationship to be defined

A resource for general clinical contexts. This edition does not assign a specific oncological relationship; selecting it for a study requires a justified question, population and purpose.