TREN
On a phone, use the table.Clicking thresholds onto the chart is far easier on a wide screen. On a phone you can type them into the table instead; the arithmetic is the same.
CALCULATOR · PURE-TONE AVERAGE

Pure-Tone Average Calculator

Click the thresholds onto the chart or type them into the table, and the tool works out five different averages from the same thresholds, showing step by step which numbers were added. Enter bone-conduction thresholds as well and it derives the air-bone gap, the degree and the type of loss; enter the speech reception threshold and it checks how well it agrees with the pure-tone average.

Enter thresholds Practise

For educational use · not a clinical record or a diagnostic tool

  • 5 averagesfrom the classic to high-frequency
  • Air and bonegap, degree and type
  • Step by stepwhere every number came from
What is on this page
1THRESHOLD ENTRY

Enter the thresholds

You can click them onto the chart or type them into the table; each updates the other instantly. A pure-tone average is calculated once all the frequencies that formula needs have been entered. To start from a ready-made example, pick one of the buttons below.

Example
Audiogram
Numeric entry dB HL
Hz Right air Right bone Left air Left bone

The • mark next to a frequency means that frequency goes into the four-frequency pure-tone average. For a frequency with no response, press the NR button beside the box. Bone conduction is measured only at 500, 1000, 2000 and 4000 Hz and the interoctave frequencies, so the box is disabled on the other rows.

2FORMULA COMPARISON

Five averages from the same thresholds

The pure-tone average is not one formula: which frequencies are averaged depends on the question being asked. Click a row in the table and that average's arithmetic opens up step by step beside it.

Average Frequencies Right Left

Click a row to see its arithmetic step by step.

Step-by-step arithmetic
Where is each average used?

    Sources: Fletcher H. (1929) · AAOO (1959) · AAO-HNS (1979) · WHO World report on hearing (2021) · ACOEM noise-induced hearing loss statement

    3SPEECH RECEPTION THRESHOLD

    Do the pure-tone average and the SRT agree?

    The speech reception threshold is an independent check on the pure-tone thresholds. If the two differ markedly, the measurement is repeated first. The comparison uses the three-frequency average, which relates best to speech; when the audiogram slopes steeply, Fletcher's best two thresholds are shown alongside it.

    4SHORT EXERCISE

    You do the arithmetic, the tool checks it

    The tool gives you a random ear and set of thresholds and you type in the four-frequency pure-tone average. Your answer is checked and the arithmetic is shown step by step. It works as a short warm-up in class.

    To begin, press New question .

    5RULES AND SOURCES

    No response, missing thresholds and rounding

    A frequency with no response

    If no response was obtained at a frequency up to the output limit of the audiometer, that frequency is not droppedfrom the average. Dropping it would make the average look better than it is, because the worst threshold would be left out. This tool includes such a frequency by adding 5 dB to the output limit at that frequency, and marks the result with ≥ : the true average is at least this value.

    Reporting the average as a lower bound is common practice; different centres use the limit itself or the limit plus 5 dB.

    A missing threshold

    If even one of the frequencies a formula needs has not been entered, that row is not calculated and the table shows - instead. Estimating a missing threshold and feeding it into the average would rest the result on a number that was never measured. The step-by-step panel names the frequency that is missing.

    So the four-frequency average is not calculated until 4000 Hz is in, and the three-frequency average not until 2000 Hz is in. If a formula's row looks empty, completing the missing threshold is all it takes.

    Rounding

    The average often does not come out as a whole number. This tool rounds the result to the nearest integer and rounds halves up: a result of 52.5 dB HL is reported as 53 dB HL. The step-by-step panel also shows the value before rounding.

    Because thresholds are entered in 5 dB steps, the three-frequency average often has a fractional part, while the four-frequency average usually lands on a whole number or a half.

    Next Audiogram Tool The full audiogram, masking checks, a printable report and link sharing. Related Hearing Aid Selection Workshop See which device type suits the same thresholds. All of them Tools The other calculators and workshops built for audiology.