Understanding Audiometer Calibration and Test Room Certifications
Most people understand the difference between a wrench and a screwdriver, but this does not qualify them to be a mechanic. Car owners know that without regular maintenance by a qualified mechanic, their car will in time, breakdown. Nobody wants to be stranded with a broken car in the middle of nowhere. Similarly, you do not want your equipment to fail in front of a patient. Awkward…
Just as your car has a service plan with scheduled maintenance, so should your audiometer.
In a previous blog about why you should always calibrate an audiometer, we explained the risks of not doing regular calibrations and clarified calibration intervals stipulated in regulations such as ANSI, OSHA and SANS.
This article hones in on more detail regarding these intervals and will dispel some of the ambiguity around quarterly calibrations, as well as answer any questions our customers may have. We will also in this article, reintroduce the importance of room certifications.
Rehashing Calibration Requirements
Certified Calibration Laboratories
Just like you would not let an unqualified mechanic work on your car, you should not let an unqualified person calibrate your audiometer. It is critical to ensure that your calibration service provider conforms to ISO 17025 and uses equipment that complies to IEC 60318 and IEC 61672 requirements. For quality assurance and as a requirement of ISO 17025, your calibration service provider should also be ISO 13485 or at least ISO 9001 accredited. You are within your rights to ask your provider for a” Declaration of Conformance” and ISO certificate before they calibrate your audiometer/s.
Annual Calibrations (International requirement)
- It is well known that audiometers must be calibrated annually. This is referenced in ANSI S3.6, OSHA 1910.95 App E and SANS 10083.
- As the manufacturer of the KUDUwave, we recommend that the KUDUwave is evaluated and calibrated annually by an approved eMoyo service provider.
- We have partnered internationally with calibration laboratories who are certified to conduct KUDUwave audiometer calibrations. Contact us to find your closest certified laboratory for your KUDUwave calibration.
Periodic / Quarterly Calibrations (South African occupational health requirement)
- Mobile units moved from the original site of calibration by road, rail or air need to be calibrated at least every three months as per SANS 10154-1:2012, if certain controls are put into place.
- If a KUDUwave audiometer is used in a mobile scenario, meaning it is taken from one site to another site to do occupational hearing screening, it must be calibrated at least every three months. It is not necessary to re-calibrate after every move. The calibration can be validated after each move with the built-in KUDUwave X-Check.
The following information must appear on your calibration certificate
- Site of calibration.
- Date of calibration.
- The audiometer’s details including the make, model and serial number.
- Details of the earphones.
- Details of the institution who conducted the calibration.
- Scientist who signed off on the calibration.
Another perhaps unknown fact is that all medical records must be stored for up to 40 years depending on the regulation being referred to. In case of a dispute, you may need records of your calibration certificates to verify the state of your equipment at the time of the test. Contact eMoyo, and we can provide you with your historical calibration certificates from up to 11 years ago (2008).
Test Room/Booth Certifications
Most people have a basic understanding of the importance of attenuating the surrounding noise for audiometric testing. Either a sound booth is used to attenuate the noise, or a specialized headset like the KUDUwave Ambidome™ headset is used to prevent the presented tones from being masked during testing.
An aspect that not many people may realise, is the importance of controlling the environmental noise. All headsets and sound booths have a limit as to how much noise it can be exposed to before noise will infiltrate and possibly affect the audiometric test. This is called the Maximum Permissible Ambient Noise Level (or MPANL). A test room or booth is deemed suitable if the measured noise does not exceed these values for the headset used. The MPANLs are typically found in country standards like ANSI S3.1, ISO 8253, OSHA and ISO 6189. The MPANLs of the KUDUwave headset are supplied by the manufacturer.
How do you know if your test room complies to these MPANLs?
Test room certifications may be a solution to ensure your room complies to MPANLs. Room certifications entail a qualified technician coming onto your site, or to your practice, and testing the noise levels, or sound pressure levels of your room or booth at least once a year. During the assessment of the room or booth it is important that the noise conditions are at their worst. For example, peak hour traffic intervals will be noisier than periods just after when everyone is already at work and the roads grow quieter. Air conditioners, if normally operating in the test room should be switched on during the assessment. The noise from office telephones and printers must also be taken into consideration.
What intermittent noises should not be considered in the evaluation?
An ambulance siren occurring during the assessment can be ignored if this is a random event, however if you are located at a hospital, it is more likely that a siren will be heard more often, and this must be taken into consideration. It is suggested that if the sound does not occur more than four times per hour, it can be ignored during the assessment.
Normally, room certifications are valid for one year and should be repeated annually, but it does depend on the country standards. It is important to also keep a record of the ambient noise in the test room, along with the calibration certificates. This may prove difficult as most operators are mobile and the site will change frequently. The standards typically state that the operator must stop testing when a noisy event occurs. This is called subjective monitoring of noisy events. With the KUDUwave, this is not a problem as ambient noise is monitored objectively in real time. These noise levels are recorded on each audiogram report.
So now that you have a better understanding of the different calibrations needed, you also need to keep track of when your audiometer needs to be serviced. To help you keep track of your calibrations and services, we have designed an A5 sized service book. Download and print the attached calibration book and insert it in your KUDUwave case. Use it to refer to for your next calibration and hand it in to your certified calibrator to be stamped or signed after each service.