Factors Affecting Audiometric Testing Results
In this series of articles we are going to break down factors that affect the quality of testing results — the test environment, calibration, standardised procedures, clinician experience, and a whole suite of subjective factors. All are vital for accurate and reliable results. This post deals with the audiometric testing environment.
Maximum Permissible Ambient Noise Levels (MPANLs)
The test environment plays a key role. Tests should occur in an environment that meets Maximum Permissible Ambient Noise Level (MPANL) 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 expectation is that sound-treated micro booths or "sound booths" are the only way to achieve reliable results or adequate MPANL attenuation — however, there are provisions in AS 1269.4 for this, and it is not always the case.
Certifying the Environment on the Day
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.
If you want to compare audiometric testing results between years, between providers, or between locations, it is important to confirm that the ambient noise levels in the testing environment have been validated. We always ask for the MPANL certification — it is required under AS/NZS 1269.5:2017.
Key Clauses in AS 1269.4:2014
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, ensuring that background noise does not interfere with hearing threshold measurements.
AS 1269.5:2017 (Occupational noise management — Noise control and hearing conservation programs) specifies the 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.