How to Test Hearing Protector Devices

Ear plugs and ear muffs are designed to protect your ears from loud noise. Choosing the most appropriate device depends upon the noise you will be exposed to and the amount of noise you need to have blocked.

Every hearing protector device is given a noise reduction rating (NRR) for the amount of noise that can be blocked. That NRR number is a helpful guide but does not necessarily reflect the actual amount of protection you will obtain. The key to ensure that your ears are adequately protected is to have your hearing protector device evaluated.

Things You'll Need

• Sound-treated room
• Calibrated audiometer
• One calibrated speaker
• Hearing protector devices
• Audiogram

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Instructions

• 1

  Position the listener's chair in the sound-treated room at the calibrated position facing the speaker.

• 2

  Tell the listener that he will be tested without the hearing protection devices.

• 3

  Instruct the listener to raise his hand each time he hears a sound called a warble tone.

• 4

  Set the frequency control to 1000 Hz and set the intensity level to 60 dB.

• 5

  Present the warble tone for one second and wait for the listener to respond.

• 6

  Lower the intensity level by 10 dB if the listener raises his hand, then present the softer warble tone.

• 7

  Repeat Step 3 until the listener no longer raises his hand, indicating that he did not hear it.

• 8

  Raise the intensity level 5 dB, then present the warble tone and wait for the listener to respond.

• 9

  Raise the intensity level another 5 dB if the listener does not respond. Continue to raise the level in 5 dB steps until the patient responds.

• 10

  Note the intensity level on the audiogram when the patient responds.

• 11

  Repeat Steps 6 through Steps 10 until the same intensity level is noted two or three times. This is the threshold or softest level that the listener can hear that frequency.

• 12

  Repeat Steps 2 through 8 for test frequencies 2000 Hz, 4000 Hz, 8000 Hz, 250 Hz, and 500 Hz. Proceed to Step 13 when testing of 500 Hz is completed.

• 13

  Instruct the listener to put on his hearing protection device then repeat Steps 4 through 12. Go to step 14 when Step 13 is completed.

• 14

  Calculate the amount of sound protection at each frequency by subtracting the thresholds measured without hearing protection from the thresholds measured with the devices.