OAEs - Instrumentation & Calibration

Question 1

How is an OAE performed and measured?

Answer 1

• Stimulus presented is two tones of different frequencies (f1 & f2)
• Response is the OAE at a different frequency (2F1-F2)
• Response is compared with the noise floor (should be at least 6dB)

Question 2

As a clinician, why should we care about calibration as it relates to OAEs?

Answer 2

• Important to make sure that you know precisely what stimulus is being delivered to the ear
• You want to make sure that what you think is a response is truly a response rather than simply artifact
• If your system is not working correctly, you might need to be able to troubleshoot the source of the problem

Question 3

Why are equipment standards important?

Answer 3

We want to make sure equipment we use in the clinic adheres to basic requirements.

Question 4

What are standard setting groups relative to audiology equipment?

Answer 4

American National Standards Institute(ANSI) and International Electrotechnical Commission(IEC)

Question 5

In the US, what regulatory body approves equipment for use?

Answer 5

Devices used in the US must be approved by the FDA

Question 6

What are some distinctions between OAE screening devices and diagnostic OAE devices?

Answer 6

• Whether the display is pass/refer or provides full details of the OAE responses
• Frequency range
• Signal intensity level range
• Storage and printout requirements of the devices

Question 7

What are some primary sources of artifacts related to OAE testing?

Answer 7

• Debris migrating into the probe
• Cross-talk
• System distortion

Question 8

What are some of the challenges with calibration in the ear canal?

Answer 8

• Standing waves in the ear canal due to the interaction of the stimulus and reflected sound coming back to the probe from the TM
• Estimation made by the probe is not accurate

Question 9

The goal of using power or intensity calibration:

Answer 9

-To know precisely the impedence characteristics of the source (OAE probe) and the load (ear canal and TM) immediately before starting the OAE measurement.