Hearing loss is a multifaceted issue with a wide range of contributing factors. While those of us who work with noise machinery or in loud environments are most at risk, there are many affected by genetic conditions like Meniere’s disease which can cause hearing loss. What is more, conditions like diabetes and hypertension can also make hearing loss worse. In most cases, hearing loss is caused by damage to the tiny inner hair cells that transmit sound information through the ear to the brain. 

Most of the time, this damage takes place slowly and incrementally and it often takes years or decades until the hearing loss becomes noticeable enough for those affected to get in touch with their local hearing instrument specialist (HIS). Most of the time, these professionals can diagnose the causes of hearing loss and pinpoint missing frequencies with complete accuracy. This data is then used to calibrate a hearing aid.

In some rare cases, however, people who have hearing loss can still read as normal in a hearing test. In order to understand why, we need to look at:

How hearing tests work

One of the most common hearing tests employed by a HIS is an audiometry test. Here, the HIS uses a machine called an audiometer. The client puts on a pair of headphones and the HIS plays a series of sounds across a range of frequencies. If the client can hear the sound, they click a button. If they cannot, they do nothing. The data from this test is used to ascertain the extent of the hearing loss, find out which frequencies can and cannot be heard and calibrate a hearing aid accordingly. 

In some cases, however, hearing loss can be hidden and those affected can ace the audiometry test but still struggle to follow conversations in a busy room or follow the plot of a TV show unless the volume is turned way up.

How could this be?

“Hidden” hearing loss and how it can slip through the net

An audiometry test takes place in a quiet room, wearing a set of noise cancelling headphones. It doesn’t replicate the conditions such as a loud bar or restaurant where someone affected by hearing loss might have the most trouble. As professor of communicative disorders and sciences Richard Salvi told the Hearing Review in 2017, sometimes people can have fairly serious hearing loss as a result of inner ear hair cell damage yet everything may still appear normal in the context of an audiometry test because the brain is overcompensating.

Salvi likens the audial response in the human brain to a radio with gain control that can effectively turn up the volume under certain conditions. However, while the brain can carry out its own amplification under the right circumstances, it will still struggle with fidelity. Therefore, they may hear well enough to report the sound of a simple tone in an audiometry test but not well enough to identify a friend’s voice in a noisy cafe.

The importance of comprehensive testing

As we can see, while audiometry testing is highly accurate in most cases, it is not infallible. This is why most audiologists and hearing instrument specialists will carry out more tests than this alone to ascertain the cause and extent of hearing loss.

They will usually carry out a full examination of the inner ear with a tool called an otoscope as well as carrying out a series of conductivity tests called rinne and weber tests to test air and bone conductivity which also play an important part in hearing. They will conduct a test called a tympanometry test to ensure that the eardrum is moving properly and there is nothing impinging on it to prevent proper conductivity. They’ll also look into your family and medical history to identify any seemingly unrelated conditions which might cause or exacerbate hearing loss.

How we can help

At Niagara Hearing and Speech Clinic we offer a holistic approach to hearing testing to ensure that our valued clients get the support they need from a hearing instrument that’s expertly calibrated to them. Want to know more? Give us a call today at (855) 797-8002.