Audiometry Without The Soundbooth - And Stuff About Everest
Sure, you could attempt to test hearing loss without a soundbooth, in fact many people do. You could also try to scale mount everest without a sherpa, barefoot and wearing a tutu.
It is conceivably possible, but, why on earth would you do that?
Ascending the highest point in the world compared with testing a patient’s hearing may be a bit of a stretched comparison except for the fact that both require specialised technology and equipment to even make an attempt possible.
To climb a colossal peak in sub-zero temperatures requires very specific thermotechnology to keep you from freezing to death or simply stop your frostbitten appendages from taking a walk of their own. Just the smallest gap between your boots and your pant legs will result in spine freezing air streaming up your legs resulting in dire and very much undesirable consequences.
OK, so there’s actually more in common than I initially thought.
Whether it is protection from the cold or protection from interfering noise the principle here is clear, To do either of these things you need to be able to control your environment.
In the case of audiometry, where environmental sound is your enemy, attenuation is your greatest ally. Just like a tutu is less than effective in the Himalayas, so are traditional audiological headsets as soon as it is used outside a soundbooth.
To illustrate this point, we have put together some handy tables illustrating the ability of commonly used headsets in occupational health hearing screening to block sound compared with the KUDUwave which is specifically designed for this purpose.
So let’s get to it.
First let’s look at the ability of the headsets to attenuate (block) environmental noise.
It is fairly obvious at this point that the standard headset cannot be used without a soundbooth. To be fair, these commonly used headsets were never designed, nor intended for boothless testing. It is no surprise that they cannot perform in these conditions. After all, you cannot judge a fish on its ability to climb a tree.
Next we look at the specific use of headsets in occupational health where environmental noise levels are stipulated.
(Known as MPANL or Maximum Permissible Ambient Noise Levels)
Again, not surprising that the headsets which were not made for testing in these environments without a soundbooth would not fair well.
Lastly let’s look at the typical environmental Noise Criteria grading where the different headsets can test PLH accurately without a sound booth.
Once again, these headsets, although perfectly suitable for in-booth testing, simply do not allow for testing in any other environment.
What is the secret?
Ambi-dome™ – this is our term for the KUDUwave’s unique ability to attenuate sound. It comprises 2 layers of attenuation technology, highly sensitive built-in microphones in each cup to monitor for any noise (at the ear) that may penetrate and affect the specific frequency presented. Active Noise Monitoring means that your testing is quality controlled in real-time and you are immediately notified if environmental noise is too loud to test accurately.
Now that we’ve cleared this up, you also never want to be left stranded at the summit because the equipment you have invested in isn’t working correctly.
That’s where calibration and servicing comes in.
So let’s take a quick look at a few questions you can ask your audiometer supplier before you purchase, as well as information you should get from your calibration service provider to be sure that they know what they’re doing before they get their hands on your equipment.
Does your audiometer comply to IEC 60645-1 as stipulated in SANS 10083 standard?
- Ask for an EC Declaration of Conformity to the Medical Devices Directive 93/42/EEC. This declaration must stipulate the specific make and model of the audiometer in question.
- FDA is not accepted in South Africa, only the European CE mark. The CE mark should be visible somewhere on your audiometer. Whether the CE mark is there or not, ask for the CE certificate to be absolutely sure.
Is the audiometer registered with the South African Department of Health Radiation Control?
In South Africa, all audiometers are legally required by the Hazardous Substances Act (Act No.15 of 1973) to be registered with the Department of Health Radiation Control
- Ask for the Department of Health Radiation Control License that specifies the make and model of your audiometer.
- You can also view the full list of registered devices here. If its not on this list, don’t buy it.
Calibration Service Providers:
Does your calibration service provider comply to the requirements of SANS 10083?
- All calibration companies in South Africa are regulated by SANS 10083 and as such must implement and maintain a quality management system in order to comply with the standard. This quality management system should be audited on a regular basis by an entity such as a European Notified Body. Ask for evidence.