6 reasons insert earphones should be the audiometry standard

By Hlolo Ramatsoma on 2018.July.26
Hlolo Ramatsoma

“Millions saw the apple fall, but Newton asked why.’’ - Bernard Baruch. As clinicians, we often follow the same protocols and procedures we learned in university. These procedures become a habit, we are so used to them that we don’t even think about them anymore. It’s just the way we do it, the way we have always done it.

This reminds me of a story a colleague shared with me a while ago.

The pot roast story. It goes like this...

A mother was teaching her child how to make a pot roast. The mother explained each step of the process to the child as she went. The recipe was an old hand-me-down that had been gifted from mother to daughter from generation to generation. As the mother was preparing to put the pot roast in the oven, she said, ‘’now we cut off the end of each side of the meat.’’. The child curiously asked why. The mother thought carefully and replied, ‘’that is the way we’ve always done it. That's the way your grandma did it, and that’s how I am doing it.’’. The child, not satisfied with the answer called to ask her grandma who replied, ‘’that is the way we’ve always done it. That's the way my mother did it, and that’s how I do it.’’. The child, still not satisfied, called her great-grandma to ask the same question. She asked, “Why do we cut the ends off the pot roast before putting it in the oven?”. To which her great grandma replied: “When I was a young woman, we had a very small oven. The pot roast wouldn’t fit in the oven if we didn’t cut the ends off.”.

In healthcare, we are often guilty of this same thinking. Things have always been done this way, therefore, this is the way things must always be done. Often, many procedures could be more efficient, more effective and in some cases, there are better ways of doing things. We should always remain conscious of the reasons behind the things we are doing as a guiding measure and a key to continuous improvement.

One example is the reliance on supra-aural headphones when the evidence and benefits are clearly shown in favour of insert earphones (IE) for audiometry (both screening and clinical).

6 reasons why insert earphones should be used in your clinic

Improved Noise Reduction:

Foam insert ear tips seal the external auditory canal and block out ambient noise. IE can reduce 30 dB or more of noise. This ensures testing down to lowest thresholds, and that the patient is not distracted by ambient noise. IE make it possible to test in a relatively quiet room, something supra-aural headphones cannot do. Many studies show that traditional headphones are suited to use within a sound-treated room or booth as they do not reduce noise sufficiently to test to lower thresholds.

Better interaural attenuation:

During pure tone audiometry, sounds delivered to the test ear may cross over to the non-test ear through bone conduction, a phenomenon known as crossover. With supra-aural headphones, pure tone signals delivered at a high decibel level, 40 dB or more, can cause the vibrations of the headphone to vibrate the bones of the skull, carrying the signal directly to the non-test ear. IE provide far greater inter-aural attenuation, which means that the signal must be much louder before it can cross-over to the non-test ear. 70 dB difference between the ears is a conservative estimate. This allows for a person with relatively normal hearing in one ear and severe hearing loss in the other to be accurately tested, without the need for masking, as it can be assumed that there is no crossover.

Improved hygiene:

To avoid cross-infection between people being tested, supra-aural headphones need to be cleaned in between patients, or a new set of headphone covers need to be used for each patient. Realistically, this doesn't happen. IE were designed for a single use purpose, therefore, they are disposed after every patient use. This avoids cross infection completely.

Avoid Collapsing ear canal:

In some individuals, the pressure of supra-aural headphones on the outer ear causes the ear canal to collapse or close. This leads to artificially elevated thresholds (inaccurate results). Once the supra-aural headphones have been removed, the ear canals reopen but the results are already affected. With IE, one avoids the collapsing of ear canals thus getting accurate patient results.

Better Patient Comfort:

IE are manufactured with a spongy foam material, furthermore, they come in various sizes, and one can roll them to their smallest diameter to ensure the right and comfortable fit for the patient.

Improved Clinical assessment:

In the past, audiologists remained cautious in using IE due to a paucity of experimental data demonstrating comparability between other widely used transducers and IE. However, today there are various studies that show no clinical significance among pure-tone thresholds and speech audiometry results in individuals with normal and impaired hearing. This further advocates for the use of IE in clinical assessments, for reliable and accurate audiometric results.

It just makes sense to switch to insert earphones. However, this does not mean that IE do not have their own challenges too. But the benefits far outweigh the disadvantages.


Tags: Audiometry