What Is Pure Tone Audiometry?

Pure tone audiometry is a standardized subjective behavioral response audiometry that tests hearing sensitivity. It includes air conduction hearing threshold and bone conduction hearing threshold testing.

Pure tone audiometry

Right!

Pure tone audiometry is a standardized subjective behavioral response audiometry that tests hearing sensitivity. It includes air conduction hearing threshold and bone conduction hearing threshold testing.

Chinese name

Pure tone audiometry

Test

Audiometric, standardized subjective behavioral response audiometry

Including

Air conduction hearing threshold and bone conduction hearing threshold test.

Common test items

Air conduction audiometry

Test purpose: To reflect the hearing level of the smallest sound of each frequency that the subject can hear in a quiet environment, to understand whether the hearing is normal or not, and the degree and nature of hearing loss, and use it as a basis for diagnosis and treatment.

The basic principles of the test: first conduct airway audiometry, and first measure the bone conduction of the ear with better airway hearing threshold, and cover the non-test ears during bone conduction audiometry.

Pure tone audiometry audiometry

(1) Give the test tone for 1-2 seconds / times. The interval between the sounds should be irregular, but the interval should not be shorter than the duration of the sound.

(2) The first step: lifting method: first use 1000Hz 40dBHL to familiarize the test subject, if there is no response, increase the test tone by 10dB, until a response is made, reduce the test tone by -10dB, and then gradually increase it to respond , Give the test tone at the same listening level after an interval of 1-2 seconds, and if you respond again, you can start listening; ascending method: familiar with the test tone, drop 10dB to the sound, if you can't hear it, increase the sound by 5dB. Level until reaction.

(3) The second step: lifting method: After responding, add 5dB, and then decrease by 5dB, until there is no response, then decrease by 5dB, and then increase by 5dB, then repeat the ascent 3 times, and listen 3 times. The minimum number of sound responses is averaged to obtain the listening threshold level; the rising method: to respond, drop 10dB, and then increase by 5dB, and repeat the sound 5 times, of which the response at the same hearing level is the hearing threshold level .

(4) The third step: test the next frequency, which can start at 10dB below the listening threshold just measured, and then complete each measured frequency in this way.

(5) Step 4: Measure the other ear with the same method.

(6) The order of test frequency is: 1000, 2000, 3000, 4000, 6000, 8000, 1000, 500, 250Hz. When copying 1000Hz, the result is more than 10dB from the first time. The error is within 5dB. The entire process is limited to 20 minutes (or a few minutes of intermediate adjustments).

When the pure sound level of the test ear is greater than the non-test ear bone conduction threshold plus interaural attenuation (IA), there can be cross-hearing, and masking noise should be added to the non-test ear.

(1) Step 1: Without masking the hearing threshold of the test ear, give the non-test ear a narrow-band noise equivalent to the effective masking level of the hearing threshold level, and increase the noise step by step until no test sound is heard, or the test level is exceeded. .

(2) Step 2: If the pure tone can still be heard when the noise level is equal to the test tone, this pure tone is the listening threshold level. If the pure tone is masked, increase the pure tone level until the pure tone is heard again.

(3) Step 3: Add 5dB noise. If you cannot hear the test tone, increase the test tone until you can hear it. Repeat this step until you add 5dB noise twice in a row. This pure tone level that can still be heard after adding 10dB is the listening threshold level.

Note: There is a possibility of excessive masking (noise transmitted to the subject's ear). That is, when the masking noise given by the non-test ear exceeds the inter-ear attenuation level, it can be transmitted to the cochlea of the test ear, so that the signal originally heard by the test ear can no longer be heard. ^[1]

Pure tone audiometry bone conduction audiometry

When testing the bone conduction hearing threshold, the hearing should be measured when the test ear is not blocked (no air conduction headphones), and the non-test ears can be masked by wearing air conduction headphones. In addition, the bone-conducting vibrator should avoid contact with the auricle, otherwise the sound can be transmitted to the external ear canal by vibrating the auricle.

(1) Step 1: Wear the bone conduction earphone (part of the mastoid area behind the auricle) of the test ear, and wear the air conduction earphone on the contralateral ear, and measure the bone conduction hearing threshold without masking noise.

(2) Step 2: Add non-test ears to the effective masking level of the ear's air conduction threshold level, and gradually increase the noise until no pure sound is heard, or the noise level exceeds the test sound.

(3) Step 3: If the pure level can still hear pure noise at a level 40dB higher than the test tone, this pure tone level is the bone conduction hearing threshold level. If the pure tone is masked, increase the noise until pure tone can be heard again.

(4) Step 4: Increase the 5dB noise level. If the test tone cannot be heard, increase the pure tone until it is heard again. Repeat this step until the 5dB noise is increased twice in a row. The pure tone remains unchanged. Can hear pure tone.

During the test, pay attention to communicate with the subject at any time, observe the status of the patient, and ensure the accuracy of the behavior test.