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How to Find the Pure-tone Average

The pure-tone average is a calculation used routinely by audiologists and occupational health specialists. According to the American Speech-Language-Hearing Association, the pure-tone average (PTA) is used to calculate the degree of hearing loss in decibels. Audiologists also calculate the PTA to confirm a patient̵7;s reliability in a hearing test. Dr. Robert Dobie of the National Institute on Deafness and Other Communication Disorders (NIDCD) indicates that the PTA is used to determine the hearing handicap in workman̵7;s compensation cases for occupational hearing loss.

Things You'll Need

  • Calibrated audiometer
  • Calibrated TDH-39 headphones
  • Audiogram
  • Quiet room
  • Table
  • Two chairs
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Instructions

  1. Preparation

    • 1

      Place the audiometer on a solid table in a quiet room, plug it into the electrical socket and turn it on.

    • 2

      Place your chair in front of the audiometer so that the controls are facing you and can be easily reached.

    • 3

      Position the listener̵7;s chair on the opposite side of the table so that it is facing away from you. This will prevent the listener from seeing you operate the controls.

    • 4

      Instruct the listener that he will hear a series of tones and he should raise his hand whenever he hears them.

    • 5

      Place the headphones on the listener so that the earphone marked in red is over the right ear and the blue marked earphone is over the left ear.

    Pure-tone test

    • 6

      Set the frequency control to 1000 Hz and set the ear to be tested to the right earphone.

    • 7

      Set the intensity level to 50 dB.

    • 8

      Press and hold the presentation (or interrupt) button for one second to give the patient the tone. Wait for the listener to respond.

    • 9

      Lower the intensity by 10 dB if the listener raises his hand signaling that he heard the tone. Then present the softer tone in the manner described in Step 3.

    • 10

      Repeat Step 4 until the listener no longer raises his hand. This means that he did not hear the tone and could represent the threshold or softest level that he can hear.

    • 11

      Note the intensity level on the audiogram.

    • 12

      Raise the intensity by 5 dB, present the louder tone and wait for the listener to respond.

    • 13

      Repeat Step 7 if the listener does not raise his hand. Continue raising the intensity in 5 dB steps until the listener raises his hand signaling that he heard the tone.

    • 14

      Repeat Steps 4 through 8 until the same intensity level is noted in Step 6 two or three times. This is the established threshold or the softest level that the listener can hear that particular tone.

    • 15

      Set the frequency control to 2000 Hz and repeat Steps 2 through 9.

    • 16

      Repeat Steps 2 through 9 for test frequencies 4000 Hz and 500 Hz.

    • 17

      Set the ear to be tested to the left earphone and repeat Step 2 through Step 11.

    Calculating the pure-tone average

    • 18

      Add up the threshold levels for 500 Hz, 1000 Hz, 2000 Hz, and 4000 Hz for the right ear.

    • 19

      Divide the sum of the values by four. This number is the pure-tone average expressed in decibels.

    • 20

      Repeat Step 1 and Step 2 for the left ear.

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