Audiometric Testing Equipment & Booth Standards: What Compliant Testing Requires

A test conducted with sub-standard equipment is not AS/NZS 1269.4 compliant and therefore not legally valid for WHS purposes. Many Australian businesses don’t realise that purchasing an inexpensive audiometric testing service is not just a cost-cutting measure—it’s a potential compliance failure waiting to expose the business to liability. This article outlines exactly what equipment and booth standards are required for compliant testing.

When you request a testing quote, the right questions to ask involve equipment standards. This guide tells you what those standards are and how to verify compliance.

Why Equipment Standards Matter

WHS Regulation 58 requires audiometric testing to be “conducted in accordance with AS/NZS 1269.4:2014.” This standard specifies not just testing methodology but equipment specifications. If equipment doesn’t meet the standard, the test fails to meet the regulation and is not legally valid.

Implications:

If a workplace NIHL claim occurs and the employer’s defence relies on a baseline test done with non-compliant equipment, the court may disregard the test entirely
A regulator audit of testing records will flag non-compliant equipment as a breach
The business loses the protection that “we were testing” should provide

Bottom line: Compliance with equipment standards isn’t optional—it’s the foundation of valid testing.

Audiometer Standards (IEC 61672, AS 3655)

The audiometer—the device that produces and measures hearing thresholds—must meet specific international standards:

IEC 61672 (International Electrotechnical Commission Standard)

This is the overarching standard for sound level measurement and audio equipment. Audiometers used in clinical or occupational settings must comply with IEC 61672 specifications for accuracy and precision.

AS 3655 (Australian Standard for Audiometers)

Australia’s specific standard for audiometers. AS 3655 defines two types:

Type 1 Audiometer (Clinical Grade)

Accuracy: ±3 dB HL across the testing range
Frequency accuracy: ±1% of nominal frequency
Used for: Clinical and occupational health testing, medicolegal assessments
Cost: $30,000–$60,000 per unit
WHS Requirement: Required for AS/NZS 1269.4 compliance

Type 1 is the mandatory standard for workplace audiometric testing in Australia.

Type 2 Audiometer (Screening Grade)

Accuracy: ±5 dB HL (less stringent)
Used for: Screening, research, preliminary assessment
Cost: $5,000–$15,000 per unit
WHS Use: NOT compliant for occupational health testing under AS/NZS 1269.4

If a provider uses a Type 2 audiometer and claims it’s “good enough,” they’re not meeting the WHS standard. Always confirm Type 1.

How to Verify Audiometer Type

When requesting a quote, ask: “What audiometer model do you use, and is it a Type 1 or Type 2?” Request the model number and ask for the specification sheet. Most Type 1 audiometers are made by brands like Interacoustics, GN Otometrics, or Maico.

Calibration Hierarchy and Schedule

A Type 1 audiometer is only valid if properly calibrated. The standard requires three levels of calibration:

Biological Check (Daily, Before Client Testing)

What it is: The audiometrist (or a reference worker with known, stable hearing) is tested before clinical testing begins to verify the audiometer hasn’t drifted.

Purpose: Catches major equipment failures before client testing

Requirement: If biological check reveals >10 dB drift, client testing must not proceed until equipment is repaired

Documentation: Daily biological check log maintained

Electroacoustic Calibration (Every 6 Months)

What it is: Equipment is connected to an acoustic calibrator (a device that produces a known sound level in a known acoustic coupler) and test signals are run to verify frequency accuracy and intensity accuracy at each frequency.

Standard: Must comply with IEC 61672 specifications (±3 dB HL for Type 1)

Requirement: Every 6 months minimum

Documentation: Electroacoustic calibration certificate issued

Full NATA-Accredited Annual Calibration

What it is: The equipment is sent to or tested by a NATA (National Association of Testing Authorities) accredited laboratory, which performs comprehensive testing against defined standards.

NATA accreditation importance: NATA-accredited labs are independent, professionally assessed, and maintain traceability to national/international standards. Their certificates are recognised by regulators.

Requirement: Annually minimum

Documentation: NATA calibration certificate with laboratory details, date, and scope

What to Ask Your Provider

“Can you provide current calibration certificates for your equipment, including the most recent NATA-accredited calibration? When was it calibrated?”

Expected answer: “Our most recent NATA calibration was [date], performed by [NATA lab]. Here’s the certificate.” If they can’t produce certificates immediately, their equipment may not be properly maintained.

Sound-Attenuating Booth Requirements

The testing environment must meet specific ambient noise limits. This is why sound-attenuating booths are essential.

Maximum Permissible Ambient Noise Levels (AS/NZS 1269.4)

The booth must achieve these maximum noise levels:

250 Hz: ≤70 dB SPL
500 Hz: ≤60 dB SPL
1000 Hz: ≤55 dB SPL
2000 Hz: ≤50 dB SPL
4000 Hz: ≤45 dB SPL
8000 Hz: ≤40 dB SPL

Why these levels? They ensure that background noise doesn’t interfere with hearing the test tones, especially at high frequencies where test tones are very quiet.

Practical implication: Testing in an open office, meeting room, or even a quiet warehouse almost certainly violates these limits. A purpose-built sound-attenuating booth (usually a mobile booth brought to the test site) is necessary.

Types of Booths

Portable/Mobile Sound-Attenuating Booths

Standard for occupational testing: Mobile booths are self-contained, sound-isolating enclosures (resembling a small phone booth or cabin) that achieve the required ambient noise limits. They’re transported to the test site.

Pros: Meet AS/NZS 1269.4 standards; eliminates need for pre-existing quiet space at client site; portable

Cons: Slightly claustrophobic for some workers; requires space for booth setup

Fixed/Installed Booths

Some large facilities (occupational health clinics, hospitals) install permanent sound-proof testing rooms.

Pros: Comfortable, professional environment; permanent

Cons: Expensive ($50,000+); requires renovations

Testing Without a Booth?

AS/NZS 1269.4 allows testing without a booth IF the ambient noise levels are met in the testing area. In practice:

A quiet office might achieve 50–55 dB at 1000 Hz but will exceed limits at lower frequencies (from HVAC, traffic, etc.)
An industrial site almost always exceeds limits without a booth
Testing without a booth in real workplaces is almost never compliant

Red flag: If a provider says they can test “in your office” without a booth, ask how they meet the ambient noise limits. If they can’t answer convincingly, the testing is likely non-compliant.

Circumaural Earphone Specifications vs Insert Earphones

There are two types of earphones used in audiometry:

Circumaural Earphones (Over-Ear Headphones)

Appearance: Large headphones that cover the entire ear

Acoustic properties: Create an acoustic coupler (enclosed space) that affects frequency response. The reference equivalent threshold sound pressure level (RETSPL) is specifically defined for standard circumaural earphones.

Use in occupational testing: Most common; most reference data (normal thresholds) is based on circumaural earphones

Insert Earphones (In-Ear Plugs)

Appearance: Small earpieces inserted into the ear canal

Acoustic properties: Different frequency response than circumaural due to different acoustic coupler characteristics. RETSPL values differ.

Use: Valuable when circumaural earphones are uncomfortable (e.g., people with hearing aids, ear canal abnormalities) or when bone conduction exclusion is needed

Consideration for comparison: Results from insert earphones cannot be directly compared to circumaural results without adjustment. If using insert earphones, this must be documented.

Documentation Requirements for Calibration

Compliant testing requires documented proof of calibration:

NATA calibration certificate: Lab name, dates, equipment model, scope of calibration, accreditation number
Validity: Must be current (within 12 months)
Accessibility: Should be available on request to regulators or workers
Your records: Keep copies of calibration certificates for your auditing files; they demonstrate you engaged a compliant provider

A testing provider should be able to produce a current calibration certificate on request within days. If they can’t or become evasive, it’s a red flag.

How to Verify a Provider’s Equipment Compliance

Use this checklist when evaluating an audiometric testing provider:

Equipment Checklist

Audiometer model and type: _____ (confirm Type 1)
Acoustic coupler/earphone type: _____ (circumaural standard)
Most recent NATA calibration date: _____ (must be within 12 months)
NATA accreditation number of lab: _____ (verify at nata.com.au if you want)
Can provider provide calibration certificate immediately: _____ (Yes/No—should be Yes)

Booth Checklist

Sound-attenuating booth used: _____ (Yes/No)
If no booth, how are ambient noise limits verified: _____ (should have noise survey data)
Booth maintenance/testing schedule: _____ (should be regular)

Questions to Ask Your Audiometric Testing Provider About Their Equipment

“What is your audiometer model number? Is it Type 1?”
“When was your audiometer last calibrated by a NATA-accredited lab?”
“Can you provide your current calibration certificate?”
“Do you use a sound-attenuating booth? What are its specifications?”
“How do you verify that ambient noise levels meet AS/NZS 1269.4 at our test site?”
“What earphones do you use (circumaural or insert)?”
“Can you confirm compliance with AS/NZS 1269.4:2014?”

A reputable provider will answer all these questions promptly and provide documentation.

Frequently Asked Questions

Q1: Does a cheaper provider use worse equipment?

Not necessarily, but very cheap providers may cut corners on calibration or use older equipment. Equipment compliance matters more than price.

Q2: Can we use our own audiometer if we buy one?

Technically yes, but you’d need to maintain it to standard (NATA calibration, daily biological checks, record-keeping), and someone would need training. Outsourcing is usually more practical for small businesses.

Q3: What if we test in our own quiet room without a booth?

Unless your room meets the specific dB limits at all frequencies (unlikely), it’s non-compliant. Using a mobile booth is the standard approach.

Q4: How often should calibration occur if testing is only annual?

Calibration schedule is independent of testing frequency. Equipment must be calibrated every 6 months (electroacoustic) and annually (NATA), regardless of how often testing occurs.

Q5: If a provider doesn’t have current calibration, can we still use them?

No. Testing with uncalibrated equipment is non-compliant. Don’t proceed without current calibration proof.

Q6: What’s the cost of proper calibration?

NATA calibration typically costs $800–$2,000 per audiometer annually. This is included in the testing provider’s business model.

Q7: Can we request a specific earphone type?

You can request, but circumaural is standard. If insert earphones are used, this must be noted in the report and results adjusted accordingly.

Q8: What if results seem unusual—could it be equipment?

It’s possible. Request the provider’s calibration certificate and ask when the equipment was last serviced. If equipment is out of calibration, results are unreliable.