Why Regular Calibration Is As Important As Exercise.

We are all acutely aware of the fact that in order to stay healthy we need to exercise. We are especially aware after a long cold winter or summer holiday. While the list of benefits we gain from physical activity including longer life, improved vitality and weight-loss, many of us still don't do it.

But what on earth does exercise have to do with audiometers?


Actually, it's not just audiometers. Most “measurement” equipment needs it and medical devices, especially so.

Imagining an ECG doing lunges or a stethoscope in a yoga pose may bring a smile to your face but it is obvious that equipment can't exactly “get physical”.

“Exercise” falls within the domain of maintenance, and whether you are putting on your running shoes or having your equipment serviced, both are equally important to ensuring quality and longevity.

Exercise has a direct benefit to ourselves, our bodies and by extension, our lives. Similarly, not exercising also affects only ourselves. A sedentary lifestyle may set a bad example but won't directly affect our neighbors, friends or family.

Servicing and calibrating medical equipment has vastly different repercussions.

Failure to do so will affect others (i.e. patients).

Regulations require that medical equipment is maintained regularly. Some standards are more stringent than others but in any country, it is a must. Failure to comply to these regulations or standards can have severe legal and financial consequences.

In the occupational health setting where high volume testing is the norm, having to retest patients at no charge can cost you dearly. Penalties may also be applied and licenses may hang in the balance.

Incorrect diagnosis, in all settings, can lead to legal liability on the part of the practitioner, severely affect patients and, in industrial settings, the customer can also face heavy damages.

In short, exercise is good for you, audiometer calibration and maintenance is good for everyone. Therefore, if you will indulge my metaphor only a little longer, Yes, we should be “exercising” audiometers and medical devices on a regular basis.

 

What Is Calibration?

Instrument calibration maintains instrument accuracy and is the process of configuring an instrument to provide an accurate result for a sample within the acceptable range provided by the applicable standard.

For audiometers, calibration verifies that the tones being presented across the frequency spectrum are within the required parameters. It ensures that when an audiometer is instructed to present a 500 Hz tone at 10 dB the correct values are received by the patient. It is a guarantee that the tones are accurate and so are the test results.

Types Of Calibration

There are two main methods of calibration that must be completed at a regular basis. Commonly referred to as electro-acoustic calibration and biological/subjective testing.

Larson_Davis Type 11 Sound Level Meter

 

Electro-acoustic Calibration(EAC)

EAC is performed by a qualified technician in laboratory or within laboratory conditions. Generally conducted on a annual basis, EAC verifies that the decibels and hertz are correctly presented according to the number of wavelengths per second and the volume respectively. EAC determines the current output of the device. Once determined, adjustments can be made to ensure correct output.

Once calibrated, you will be issued with a calibration certificate proving that the device is suitable for use. This will include the date of calibration which determines the period of validity.

Note: It is common for audiometer manufacturers to stipulate a calibration interval of at least once per year. Some standards require different calibration intervals and supersede the manufacturers recommendations. Eg. In South Africa, all portable audiometers used in occupational health should be calibrated at least every 3 months.

biological audiometer calibration

 

Biological/Subjective Testing

This calibration is the clinician/user’s way of verifying that the audiometer being used is still within calibration norms and is working as expected. This biological/subjective test should be performed on a daily basis prior to testing and does not replace EAC.

Generally, this test is performed on a human subject of known hearing values. To do this a person with normal hearing levels is tested on both ears, the transducers are then swapped around and the test repeated. Note that you are using the same ear to test both transducers, so the results should be similar. The results should be within 0 - 10 dB of each other. If not, the audiometer should be re-calibrated (electro-acoustic) prior to using the audiometer again.

There is an easier and quicker way of doing this with a tool that now comes standard with all KUDUwave Devices. X-check (cross-check) is a digital calibration verification tool built into the device. It enables accurate (within 5dB) calibration verification to objectively ensure the precision of your results. This turns a traditionally “subjective” test which can be affected by the subject’s health into an objective and highly accurate test.

Using X-check is really easy and will save you a ton of time and grey hair.

It's clear that, like exercise, calibration, calibration checks and servicing are vital in ensuring the quality of medical devices and the results they produce. While there is cost and effort involved, these don't outweigh the benefits in terms of quality of test results, patient care and risk management.

Unlike exercise, maintenance is as vital to you as the professional as it is to the patient, company and healthcare system as a whole.

X-check Biological Calibration replacement

 

Hlolo Ramatsoma

Written by Hlolo Ramatsoma

Hlolo is a clinical, research & support Audiologist at eMoyo. He is involved in many parts of the business, from consulting to R&D to supporting and training customers. He earned his BSc in Audiology from the University of Cape Town and is an experienced clinical audiologist specialized in ototoxicity monitoring, product specialist and training audiologist.

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