What is Hidden Hearing Loss?

An independent audiologist near me, reviews a hearing test.

I recently had the pleasure of spending my Saturday undertaking CPD (continual professional development). No, I am not being sarcastic. When I say ‘pleasure’ you know I’m telling the truth – I love learning about ears and sharing my knowledge with you!

The first of the four learning areas in the conference fascinated me. Dr Joaquín Tomás from the National Acoustics Laboratory of Australia (NAL) presented on ‘Current Trends in Hidden Hearing Loss (HHL)’.

Hidden Hearing Loss (HHL) is defined as experiencing hearing difficulties with no measurable hearing loss. That is, your ‘beep test’ results are ‘within normal limits’. People with HHL typically report significant difficulties hearing and understanding speech in low to high levels of noise. For example, in the car, with music playing, or in a crowded restaurant. HHL can affect a person’s quality of life, negatively affect their mood and lead to reduced willingness to socialise. This is due to how hard they must try to hear, fear of appearing rude (if they don’t respond to what someone is saying) or embarrassed for responding incorrectly. This last one is particularly relevant if they know they will be meeting someone new. Sufferers may be told ‘there is nothing wrong with your hearing’ if their hearing test was ‘normal’ which may lead to them feeling frustrated or invalidated.

HHL, also known as an ‘early sign’ of measurable hearing loss, results from exposure to loud noise. Its not just industrial noise in the work place though. It means any amount of exposure to noise at a high level, for any amount of time. Even if it was ‘just that one time we went shooting rabbits as kids without hearing protection’. This is enough to do damage to the hearing system, and unfortunately that damage only accelerates with ageing.

At a cellular level there are underlying mechanisms within the auditory system that explains HHL. In simple terms, because of noise exposure, the wiring for hearing has become faulty. This means that the message of sound received by the ear no longer makes it up to the brain properly. Instead of a crystal-clear message, the brain receives a distorted message; one it can’t understand, like in a game of ‘Chinese Whispers’.

Dr. Joaquín Tomás also discussed how they identify and measure these mechanisms in the body (using electrodes to capture brain and brain stem activity in response to sound). He also mentioned the possibility of restoring specific cellular function through therapeutic interventions (although they have only experimented on animals so far). Additionally, he talked about utilizing clinical interventions and readily available technology (including over-the-counter devices) that could help minimize listening effort for people with HHL. Finally, participants provided feedback on the pros and cons of the technology used in the studies.

It was a wonderful day of learning! I’m very grateful for the opportunity to expand my knowledge of the auditory system. It helps to understand what my patients may be experiencing, to validate their concerns, and determine how we can work together to try and make things a little easier. 😊

Penelope Woods is the Founder and Principal Audiologist at A Better Ear. She holds a Master of Audiology from the University of Queensland and a Bachelor of Music from the Queensland Conservatorium. All information is general in nature. Patients should consider their own personal circumstances and seek a second opinion.