by
Glenda Demaree
NOTE: for more updated information, please also check out www.hyperacusis.net.
Hyperacusis is used to describe a high level of sensitivity to sound. It is also known as dysacusis, oxylacusis, hypersensitive hearing, or phonophobia. Persons with hyperacusis do not show abnormalloudness growth but an abnormal discomfort for suprathreshold sound (Barnes & Marriage, 1995). Audiograms for hyperacusis sufferers are typically normal. They show normal sound thresholds but the sensitivity level is above normal. The comfort level for most people is below 100 decibels. People with hyperacusis can experience discomfort at 40 to 50 decibels or lower (Schwade, 1995). The disorder may be frequency-specific (Schwade, 1995). Not all sounds of the same loudness (number of decibels) cause discomfort, but only sounds within a certain range, thus a small change of frequency may cause discomfort at low volume.
The prevalence rate of hyperacusis is unknown. It frequently occurs with tinnitus, which afflicts approximately 40 million poeple in the United States (Hazell & Jastreboff, 1933). A questionnaire in a clinic population by Sanchez and Stephens (1997) found that eight percent of tinnitus sufferers have hyperacusis. These two studies would suggest about 3 million people in the United States have hyperacusis. Further a survey conducted by the Autism Research Institute found up to 40% of children with autism to be affected by hyperacusis. Hyperacusis also has an occurence rate of 95% in children with Williams syndrome (Borse, Curfs, & Fryns, 1997). These facts plus its comorbidity with many other diseases leads one to believe hyperacusis is not an extremely rare disease.
Hyperacusis is a poorly understood disorder resulting in many theories of etiology and prognosis. Hyperacusis can occur alone or in conjunction with other disorders. A sudden single burst of noise (Schwade, 1995), a head injury (American Speech-Language Hearing Association, 1995), or surgery to the face or jaw (Barnes & Marriage, 1995) can result in hyperacusis. Barnes and Marriage also proposed two types of hyperacusis, peripheral and central.
Peripheral hyperacusis is when the earÕs built in mechanism against loud or sharp sound seems to have been turned off. Absence of acoustic reflexes, positive history of vestibular disorders, MeniereÕs disease, or perilymph fistula account for peripheral hyperacusis. Hyperacusis co-occurring with BellÕs palsy, Ramsey Hunt syndrome, and myasthenia gravis is also considered to be peripheral hyperacusis. Hyperacusis is also an otological complication of herpes zoster (Adour, 1994) and craniomandibular disorders (Erlander and Rubinstein, 1991).
Barnes and Marriage (1995) proposed another type of hyperacusis called central hyperacusis. Central hyperacusis results in an inability to tolerate specific but not necessarily loud sounds. Certain sound waves reaching the inner ear are somehow overamplified or magnified on the way to the brain or by the brain. A global sensitivity may exist to explain central hyperacusis. Barnes and Marriage (1995) list the following clinical conditions as co-occurring with central hyperacusis: migraine, depression, pyridoxine deficiency, benzodiazpine dependence, musicogenic epilepsy, Tay-SachÕs disease, post-traumatic stress disorder, and chronic/postviral fatigue syndrome. Some manic individuals also report having a much sharper sense of hearing (American Psychiatric Assciation, 1994). Children who have autism or pervasive developmental disorder may also have hyperacusis (American Speech-Language Hearing Association, 1995).
Many treatments have been tried for hyperacusis; one which has received mixed support is the use of earplugs. Dr. Jack Vernon, director of the Oregon Hearing Research Center, and Dr. Pawell Jastreboff, director of the Tinnitus and Hyperacusis Center of the School of Medicine, University of Maryland, advise against using earplugs (Schwade, 1995). Earplugs deprive the auditory system of sound. The ears try to compensate by amplifying the weak sounds and become even more sensitive over time. For behavior management in children who have autism Borsel, Curfs, and Fryns (1997) advised parents to use earplugs, to purchase household appliances with a low noise level, and to explain the origin of the sound to the child. Using sound-absorbing draperies, carpets, and furniture, or cushioning appliances can also make everyday noises less bothersome (American Speech-Language Hearing Association, 1995).
A more consistently supported treatment for hyperacusis is sound desensitization. This treatment is used at both the Oregon Hearing Research Center (Schwade, 1995) and the Tinnitus and Hyperacusis Center (Hazell and Jastreboff, 1993). Treatment involves listening to noise just below the intolerance level for several hours a day. Over time a tolerance to sound is built up, resulting in normal environmental sounds no longer causing discomfort or pain. Individual patients respond at diffeent rates to the treatment. Some conditioning occurs rapidly, but treatment can last l to l.5 years or more.Both centers individualize The Tinnitus and Hyperacusis Center includes an otolaryngologist, audiologist, and neurophysiologist (Hazell and Jastreboff, 1993). Prior to using the noise for treatment the ear and auditory system are explained to the patient. The patientÕs thinking about hyperacusis is also examined and possibly retrained. The acoustic element of the plan is them implemented. Low level, stable, white noise is produced by a wearable noise generator. White noise is a full spectrum of frequencies that together sound like the static between stations on an FM radio.
Dr. Vernon at the Oregon Hearing Research Center individualizes sound desensitization treatment for hyperacusis. Rather than using white noise, tolerance is developed through the use of low frequency sounds called pink noise. This noise is similar to the sound of ocean waves breaking.
While medication is not used as treatment for hyperacusis, it is often used to help patients cope with stress caused by the disorder. The Tinnitus and Hyperacusis Center uses antidepressants and antianxiety drugs to help patients cope until the hyperacusis can be improved(Schwade, 1995). However, a study by Szcepaniak and Moller (1995) found L-sbaclofen, a muscle relaxant, to be effective in suppressing excitation in the ascending auditory system. Further study is needed before it is used as a treatment for hyperacusis. Another treatment used for hyperacusis is Auditory Integration Training (AIT). AIT lacks experimental evidence and is controversial (American Speech-Language Hearing Association, 1995). The treatment involves listening to modulated music with specific frequencies electively filtered. Three machines (Audiokinetron, BGC Audio Tone Enhancer/Trainer, AudioScion) are available for AIT treatments (Barkell & Malgeri, l99). Safety concerns about the equipment have resulted in the U. S. Federal Food and Drug Administration directing that additional research on the AIT devices be conducted prior to continued distribution. The safety concerns are about the specifications of the machines and their effects on the userÕs hearing ability. The American Speech-Language Hearing Association supports the need for this research (American Speech-Language Hearing Association, 1995). Another problem with AIT is no training standards and guidelines for AIT trainers.
Other treatments for hyperacusis include biofeedback and relaxation techniques (American Speech-Language Hearing Association, 1995). Meyer Rosen, a hyperacusis sufferer, has tried food desensitization, exposure of nasal passages to essential oils, neurolinguistic training, rehydration of mucous membanes, correction of head-forward posture, scalp and body acupuncture, progressive relaxation of the temporomandibular joint musculature by an orthopedic mandibular repositioning device, and the use of an earplug prescription. After much study Meyer developed an acupuncture treatment called Reflex-Correspondence Training (Rosen, 1995). All of these treatments lack scientific evidence.
All aspects of hyperacusis need future research. There appear to be many causes for hyperacusis. The physiological and psychological factors need to be determined as causing or contributing to the disorder. New treatments need to be discovered, and the present treatments need to be placed on a scientific basis. At the present time hyperacusis sufferers are receiving treatments with the hope that help will be obtained, and permanent damage will not result to their auditory systems.
For a referral to an American Speech-Language Hearing Association (ASHA) certified audiologist in your area, call ASHSÕs Information Resource Center at (800) 638-8225. Additional information can be obtained by contacting The Hyperacusis Network, write or call The Hyperacusis Network, 444 Edgewood Drive, Green Bay, WI 54302 (414) 468-4667.
REFERENCES
Adour, K. K. (1994). Otological complications of herpes zoster. Annals of Neurology, 35, S62-S64.
American Psychiatric Association (1994). Diagnostic and Statistical Manual of Mental Disorders (4th ed.). Washington, DC: Author.
American Speech-Language Hearing Association (1995). Hyperacusis. ASHA, 37, 53-54.
Barnes, N. M. & Marriage, J. (1995). Is central hyperacusis a symptom of 5-hydroxytryptamne (5-HT) dsyfunction?. The Journal of Laryngology and Otology, 109, 915-921.
Berkell, D. E., Malgeri, S. S., & Streit, M. K. (1996). Auditory integration training for individuals with autism. Education and Training in Mental Retardation and Developmental Disabilities, 31(1), 66-70.
Borsel, J. V., Curfs, L. M., & Fryns, J. P. (1997). Hyperacusis in Williams syndrome: A sample survey study. Genetic Counseling, 8(2), 121-126.
Erlander, S. I. & Rubinstein, B. (1991). A stomatognathic analysis of patients with disabling tinnitus and craniomandibular disorders (CMD). British Journal of Audiology, 25, 77-83.
Hazell, J. W. & Jastreboff, P. J. (1993). A neurophysiological approach to tinnitus: Clinical implications. British Journal of Audiology, 27, 7-17.
Moller, A. R. & Szczepaniak, W. S. (1995). Effects of L-baclofen and D-baclofen on the auditory system: A study of click-evoked potentials from the inferios colliculus in the rat. Annal of Otology Rhinology & Laryngology, 104, 399-404.
Rosen, M. R. (1995). New treatment possibilties for hyperacusis--a painful, ultrasensitivity to normal sounds (letter to the editor). American Journal of Acupuncture, 23(1), 74-76.
Sanchez, L. & Stephens, D. (1997). A tinnitus problem questionnaire in a clinic population. Ear & Hearing, 18, 210-217.
Schwade, S. (1995). Shedding light on supersensitive hearing: What to do when every small noise sounds like the big bang. Prevention, 47(8), 90-96.