hyperacusis
Hyperacusis is an abnormal intolerance to ordinary, everyday sounds, which may develop in association with tinnitus related anxiety and distress.
Decreased sound tolerance is a general term covering hyperacusis, misophonia and phonophobia. Misophonia is a strong dislike of sound and is widespread - almost everyone has a sound they have disliked at some time. Phonophobia is a specific case of misophonia where people fear being exposed to a certain sound, often in the belief that it will damage the ear; make their tinnitus/hyperacusis worse; lead to uncontrollably high levels of anxiety. Phonophobia may develop in association with hyperacusis and tinnitus. Symptoms can range from mild through to severe to extreme.
What can cause hyperacusis?
Pre-existing tinnitus, misophonia and high levels of anxiety are factors that can predispose towards the development of decreased sound tolerance. Hyperacusis may develop with a number of conditions affecting the auditory pathway (including acoustic shock injury, Meniere's Disease, otosclerosis, perilymph fistula, Bell's Palsy), psychiatric disorders, neurological injuries and disorders (including head injury, migraine), adverse reactions to some medications, autistic spectrum disorders, chronic fatigue syndrome, fibromyalgia and Lyme Disease.
How common is hyperacusis?
There is little specific data about the frequency of hyperacusis in the general population. Estimates are affected by the way hyperacusis is defined and opinions range widely. Hyperacusis is less common than tinnitus, with tinnitus severely affecting 2% of the population.
How does hyperacusis develop?
When hyperacusis develops, everyday sounds begin to appear unnaturally prominent and increasingly louder. Following exposure to some or many of these sounds, a temporary increase in tinnitus (if present) and/or hyperacusis may be noticed, and escalating sensations in the ear may develop, such as ear pain, a fluttering sensation or an intermittent fullness. This reaction can generalise to include more and more sounds. As a result, people may come to believe that their ears are no longer able to physically tolerate these sounds and/or that these sounds are causing damage to their ears or hearing and should be avoided.
The escalating anxiety about the effects of exposure to these sounds can lead to the development of misophonia and phonophobia.
How does hyperacusis affect people?
People with decreased sound tolerance often feel the need to regularly and sometimes constantly monitor their auditory environment to protect their ears and sense of hearing. As a result hypervigilance of the acoustic environment is common. Frequent monitoring of the ear symptoms described above is common.
People with significant hyperacusis generally don't tolerate any loud sounds, many moderate volume sounds, particularly if sudden and unexpected, and may not tolerate some soft sounds. High frequency (pitch) sounds tend to be tolerated less well. This can have a major impact on their lives, severely limiting their horizons and creating high levels of anxiety. Explaining such an abnormal reaction to sound to other people, including at times health professionals, is difficult and people with decreased sound tolerance often feel misunderstood, isolated and accused of malingering.
Tonic Tensor Tympani Syndrome (TTTS)
Acoustic shock and TTTS Guide for Medical Professionals
In the middle ear, the tensor tympani muscle and the stapedial muscle contract to tighten the middle ear bones (the ossicles) as a reaction to loud, potentially damaging sound. This provides protection to the inner ear from these loud sounds.
In many people with hyperacusis, an increased, involuntary activity can develop in the tensor tympani muscle in the middle ear as part of a protective and startle response to some sounds. This lowered reflex threshold for tensor tympani contraction is activated by the perception/anticipation of sudden, unexpected, loud sound, and is called tonic tensor tympani syndrome (TTTS). In some people with hyperacusis, it appears that the tensor tympani muscle can contract just by thinking about a loud sound.
Following exposure to intolerable sounds, this heightened contraction of the tensor tympani muscle:
- tightens the ear drum
- stiffens the middle ear bones (ossicles)
- can lead to irritability of the trigeminal nerve, which innervates the tensor tympani muscle; and to other nerves supplying the ear drum
- can affect the airflow into the middle ear. The tensor tympani muscle functions in coordination with the tensor veli palatini muscle. When we yawn or swallow, these muscles work together to open the Eustachian tube. This keeps the ears healthy by clearing the middle ear of any accumulated fluid and allows the ears to “pop” by equalising pressure caused by altitude changes.
TTTS can lead to a range of symptoms in and around the ear(s): ear pain; pain in the jaw joint and down the neck; a fluttering sensation in the ear; a sensation of fullness in the ear; burning/numbness/tingling in and around the ear; unsteadiness; distorted hearing. TTTS is often associated with the development of temporary tinnitus or an increase/change in pre-existing tinnitus.
It does not harm the ear to experience TTTS, and even though the TTTS symptoms can seem as if the ear is being damaged by some sounds, this is not the case. Moderate, everyday sounds are quite safe and do not harm the ear or cause a hearing loss.
TTTS-like symptoms may be due to middle or inner ear pathology, and medical investigation should be carried out to exclude this possibility, particularly if severe vertigo is an associated symptom. Conversely, TTTS symptoms in people with hyperacusis can be mistakenly diagnosed as due to middle/inner ear pathology or jaw joint dysfunction or temporomandibular disorder (TMD).
TMD can produce an episodic or constant spasm of the tensor tympani muscle, with referred ear pain and other TTTS symptoms shown to be present in up to 42% in patients with TMD. When TTTS is a secondary consequence of TMD and/or physical dysfunction of the jaw joint, the TTTS symptoms do not tend to escalate and hyperacusis is not usually present.
With TTTS associated with hyperacusis, the primary cause is related to the way sound is perceived in the brain. Hyperacusis clients with severe TTTS can develop TMD as a secondary consequence, due to the tension and strain on the muscles in and around the ear.
It is therefore important for people with hyperacusis who experience these symptoms to consult an Ear, Nose and Throat specialist/TMD specialist to ensure there is no underlying medical condition causing them.
As TTTS develops from the way intolerable sound is perceived in the brain, using strategies aiming for hyperacusis desensitisation will help reduce TTTS symptoms.
How is the brain involved in the development of hyperacusis?
P Jastreboff's neurophysiological model of tinnitus and hyperacusis:
As part of the processing of sound in the brain, all sounds are evaluated subconsciously with regard to their meaning or importance to us. Sounds that are considered important (in either a positive or negative way) will be transmitted to the more conscious parts of our brain, while unimportant sounds remain "half heard".
If a sound acquires a negative association, the limbic system in the brain becomes activated, inducing fear or irritation. The autonomic nervous system also becomes activated, provoking the "fight or flight" reaction. A conditioned response develops so that repetition of this sound enhances the activation of the limbic and autonomic systems. In people with significant hyperacusis, many sounds are evaluated in the subconscious as potentially threatening, leading to the possible development of TTTS symptoms from the subconscious need to protect the ear.
Our brain is a highly plastic organ, constantly reorganising and developing new neural connections. This means that we are able to retrain our brain to reverse the process which has led to hyperacusis and tinnitus distress.
We provide a unique, individualised program to assist you in achieving increased tolerance to everyday sound, utilising Ms Myriam Westcott's extensive experience and research in providing hyperacusis and phonophobia therapy.
A detailed description of the peripheral (the outer, middle and inner ear) and central (the brain) auditory pathway is essential to understand how hyperacusis develops.
Our program involves:
- an evaluation of the hyperacusis and its impact on you individually.
- providing detailed information about your hyperacusis and how it has developed.
- a detailed and personalised explanation of the peripheral and central auditory system, including the neurophysiological basis of hyperacusis and TTTS (if symptoms are present).
- a therapy program for managing your decreased sound tolerance.
Therapy
Practical self-management strategies to assist hyperacusis desensitisation and reduce auditory hypervigilance, personalised to suit each person's individual coping style, are developed. Sound enrichment and low level sound therapy are required as part of the desensitisation process. This may involve the use of low volume neutral sound.
Counselling in cognitive management strategies to reduce auditory hypervigilance and training in stress management and relaxation will be given.
The careful use of ear protection frequently helps maintain or allow expansion of lifestyle horizons. This may be in the form of customised solid silicon rubber plugs like those used to provide hearing protection at work and/or customised filtered musician's earplugs. The need for ear protection is evaluated and customised earplugs can be provided, with guidance given in appropriate use.
What can I expect from hyperacusis therapy?
Desensitisation to intolerable sounds is a gradual process, where the situations previously uncomfortable will become gradually less so. If hyperacusis and tinnitus are present, the hyperacusis is usually addressed first. Frequently, as the hyperacusis becomes more under control, the tinnitus becomes less of an issue.
For many people, the information and guidance provided in one appointment may be sufficient to move towards hyperacusis desensitisation. For this reason, our initial appointment time is one and a half hours. However, the time involved in a program will vary, depending on the severity of your hyperacusis and the on-going guidance and support you may require.