Evidence

The Big H: Humidity and what it means for Lyric™

Humidity level in ear canals vary. How close are we to predicting ear health issues before fitting a Lyric hearing aid?

Before I started to work with Lyric, I only used the term ‘humidity’ when I was talking about weather conditions or travelling/dreaming about travelling to hot exotic locations. I never used to think about humidity in an ear canal.

Once I started finding out more about Lyric hearing aids, I soon came to realize that humidity is a really big deal! The first thing I found out is that the residual or baseline percentage humidity level in someone’s ear canals can vary per individual and in some cases per ear. My second discovery is that it doesn’t have much to do with the temperature or humidity level of the environment. Basically you either have humid ear canals or you don’t.

So what does this have to do with Lyric, you might ask?

A normal ear canal is open allowing the skin to breathe and self-clean. When a Lyric is placed 4mm from the tympanic membrane the status quo is changed. How does the moisture flow in and out of the ear? Everything about Lyric is designed to make sure it can function in the hostile environment of an ear canal. The yellow seals are specially designed to be breathable and contain thousands of tiny open pores/ holes that allow moisture and air to pass through. The rate at which this happens is called the Moisture Vapor Transfer Rate (MVTR). The larger the surface area of breathable seals the more moisture can pass through.

Electron microscope image of the breathable seals

This constant flow is crucial to maintain a healthy ear canal. In a recent study conducted at the Audiological Consultants of Atlanta clinic looking a factors that have the potential to affect ear health with a Lyric hearing aid, percentage humidity appears to play a part. Comparing two groups A and B (A being a group that has not experienced ear health issues and B being a group that has experienced ear heath issues), it was seen that more ear health issues were observed in people who had smaller ears (smaller surface area of seals) and higher humidity (high humidity is classed as 70% or above). There were also trends seen with other factors such as size alone and the general health of the individual, but we now know that humidity is a key factor.

Another study has just been completed looking at the correlation between humidity and these other key factors in more detail. Wouldn’t it be reassuring to be able to predict outcomes for your patient before you even fit a Lyric hearing aid in their ear? For now we have to wait, but I am hopeful that this will be possible in the not so distant future.

So tonight, instead of dreaming about exotic hot and humid holiday destinations, I’ll dream about ear health instead, and hope this dream comes true!

 

 

 

To read the results in full, please go to the Phonak Evidence page.

Biggins, A. (2017). Healthy ears for LyricTM wearers – the contributing key factors. Phonak Field Study News,

 

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