FACTORS AFFECTING AUDIOMETRIC TESTING RESULTS

Part 1- The audiometric testing environment

In this series of articles, we are going to break down factors that affect the quality of testing results.

Validation of the test environment to ensure it meets Maximum Permissible Noise Levels, calibration of the audiometric testing equipment, following standardised test procedures, the background and experience of the clinician, and then a whole suite of subjective factors.

All are vital for thorough assessment and accurate and reliable results.

We will deal with the audiometric testing environment in this post.

Several factors influence the quality of audiometric testing, shaping the reliability and your confidence in the results. We have been in the industry for over 10 years and can provide some insights here.

The test environment plays a key role; tests should occur in an an environment that meets Maximum Permissible Ambient Noise Level standards. MPANL is a written metric (found on the calibration certificate) and validates whether 'background noise' at a given frequency can interfere with the pure tones produced during audiometric testing.

The industry and client expectation is that sound treated micro booths or "sound booths" are the only way to get reliable results or to achieve MPANL attenuation.

This is not always the case and there are provisions in AS 1269.4 for this. AS 1269.4 itself does not define MPANLs but requires compliance with AS 1269.5 for permissible ambient noise in audiometric testing.

Critical to any mobile testing is whether the test environment is certified prior to testing with a Class 1 sound level meter. Your mobile service provider has an obligation to certify each and every testing environment on the day of testing.

Of course, if tests are conducted in the same test conditions eg an audiology clinic, a GP clinic, a first aid room on site or a sound treated meeting room, calibration certificates are still required. So if you want to compare audiometric testing results between years, between providers, between locations, it's important to see that there has been a validation of the ambient noise levels in the audiometric testing environment.

We are often asked to compare results between say a GP or employment screening service or another provider. We always ask for the MPANL certification- it's in the standard AS/NZS 1269.5 2017

AS 1269.4:2014 (Australian Standard for Occupational noise management – Part 4: Auditory assessment) primarily focuses on hearing assessment procedures rather than specifying Maximum Permissible Ambient Noise Levels (MPANLs). However, it references ambient noise limits in the context of ensuring accurate audiometric testing conditions.

Tying the testing environment back to the Australian Standard, here are the key clauses related to Ambient Noise in AS 1269.4:2014

1. Clause 4.3.2 (Audiometric Test Environment)

   • Requires that ambient noise levels in the test environment must not exceed the maximum permissible values specified in AS 1269.5 (which deals with audiometric test room noise levels).

   • Ensures that background noise does not interfere with hearing threshold measurements.

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2. Reference to AS 1269.5

   • AS 1269.4 defers to AS 1269.5:2017 (Occupational noise management – Part 5: Noise control and hearing conservation programs) for detailed ambient noise limits.

   • AS 1269.5 specifies MPANLs for audiometric test rooms, ensuring they meet the criteria for accurate hearing assessments (e.g., ≤ 30 dB(A) for low-frequency noise).

In summary, ask your mobile audiometric testing service provider, GP clinic, or employment health service to validate their testing results with a certificate showing they meet AS 1269.5 (2017)