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Hyperacusis is used to describe a high level of sensitivity tosound. It is also known as dysacusis, oxylacusis, hypersensitivehearing, or phonophobia. Persons with hyperacusis do not showabnormalloudness growth but an abnormal discomfort for suprathresholdsound (Barnes & Marriage, 1995). Audiograms for hyperacusissufferers are typically normal. They show normal sound thresholds butthe sensitivity level is above normal. The comfort level for mostpeople is below 100 decibels. People with hyperacusis can experiencediscomfort at 40 to 50 decibels or lower (Schwade, 1995). Thedisorder may be frequency-specific (Schwade, 1995). Not all sounds ofthe same loudness (number of decibels) cause discomfort, but onlysounds within a certain range, thus a small change of frequency maycause discomfort at low volume.
The prevalence rate of hyperacusis is unknown. It frequentlyoccurs with tinnitus, which afflicts approximately 40 million poeplein the United States (Hazell & Jastreboff, 1933). A questionnairein a clinic population by Sanchez and Stephens (1997) found thateight percent of tinnitus sufferers have hyperacusis. These twostudies would suggest about 3 million people in the United Stateshave hyperacusis. Further a survey conducted by the Autism ResearchInstitute found up to 40% of children with autism to be affected byhyperacusis. Hyperacusis also has an occurence rate of 95% inchildren with Williams syndrome (Borse, Curfs, & Fryns, 1997).These facts plus its comorbidity with many other diseases leads oneto believe hyperacusis is not an extremely rare disease.
Hyperacusis is a poorly understood disorder resulting in manytheories of etiology and prognosis. Hyperacusis can occur alone or inconjunction with other disorders. A sudden single burst of noise(Schwade, 1995), a head injury (American Speech-Language HearingAssociation, 1995), or surgery to the face or jaw (Barnes &Marriage, 1995) can result in hyperacusis. Barnes and Marriage alsoproposed two types of hyperacusis, peripheral and central.
Peripheral hyperacusis is when the earÕs built in mechanismagainst loud or sharp sound seems to have been turned off. Absence ofacoustic reflexes, positive history of vestibular disorders,MeniereÕs disease, or perilymph fistula account for peripheralhyperacusis. Hyperacusis co-occurring with BellÕs palsy, Ramsey Huntsyndrome, and myasthenia gravis is also considered to be peripheralhyperacusis. Hyperacusis is also an otological complication of herpeszoster (Adour, 1994) and craniomandibular disorders (Erlander andRubinstein, 1991).
Barnes and Marriage (1995) proposed another type of hyperacusiscalled central hyperacusis. Central hyperacusis results in aninability to tolerate specific but not necessarily loud sounds.Certain sound waves reaching the inner ear are somehow overamplifiedor magnified on the way to the brain or by the brain. A globalsensitivity may exist to explain central hyperacusis. Barnes andMarriage (1995) list the following clinical conditions asco-occurring with central hyperacusis: migraine, depression,pyridoxine deficiency, benzodiazpine dependence, musicogenicepilepsy, Tay-SachÕs disease, post-traumatic stress disorder, andchronic/postviral fatigue syndrome. Some manic individuals alsoreport having a much sharper sense of hearing (American PsychiatricAssciation, 1994). Children who have autism or pervasivedevelopmental disorder may also have hyperacusis (AmericanSpeech-Language Hearing Association, 1995).
Many treatments have been tried for hyperacusis; one which hasreceived mixed support is the use of earplugs. Dr. Jack Vernon,director of the Oregon Hearing Research Center, and Dr. PawellJastreboff, director of the Tinnitus and Hyperacusis Center of theSchool of Medicine, University of Maryland, advise against usingearplugs (Schwade, 1995). Earplugs deprive the auditory system ofsound. The ears try to compensate by amplifying the weak sounds andbecome even more sensitive over time. For behavior management inchildren who have autism Borsel, Curfs, and Fryns (1997) advisedparents to use earplugs, to purchase household appliances with a lownoise level, and to explain the origin of the sound to the child.Using sound-absorbing draperies, carpets, and furniture, orcushioning appliances can also make everyday noises less bothersome(American Speech-Language Hearing Association, 1995).
A more consistently supported treatment for hyperacusis is sounddesensitization. This treatment is used at both the Oregon HearingResearch Center (Schwade, 1995) and the Tinnitus and HyperacusisCenter (Hazell and Jastreboff, 1993). Treatment involves listening tonoise just below the intolerance level for several hours a day. Overtime a tolerance to sound is built up, resulting in normalenvironmental sounds no longer causing discomfort or pain. Individualpatients respond at diffeent rates to the treatment. Someconditioning occurs rapidly, but treatment can last l to l.5 years ormore.Both centers individualize The Tinnitus and Hyperacusis Centerincludes an otolaryngologist, audiologist, and neurophysiologist(Hazell and Jastreboff, 1993). Prior to using the noise for treatmentthe ear and auditory system are explained to the patient. ThepatientÕs thinking about hyperacusis is also examined and possiblyretrained. The acoustic element of the plan is them implemented. Lowlevel, stable, white noise is produced by a wearable noise generator.White noise is a full spectrum of frequencies that together soundlike the static between stations on an FM radio.
Dr. Vernon at the Oregon Hearing Research Center individualizessound desensitization treatment for hyperacusis. Rather than usingwhite noise, tolerance is developed through the use of low frequencysounds called pink noise. This noise is similar to the sound of oceanwaves breaking.
While medication is not used as treatment for hyperacusis, it isoften used to help patients cope with stress caused by the disorder.The Tinnitus and Hyperacusis Center uses antidepressants andantianxiety drugs to help patients cope until the hyperacusis can beimproved(Schwade, 1995). However, a study by Szcepaniak and Moller(1995) found L-sbaclofen, a muscle relaxant, to be effective insuppressing excitation in the ascending auditory system. Furtherstudy is needed before it is used as a treatment for hyperacusis.Another treatment used for hyperacusis is Auditory IntegrationTraining (AIT). AIT lacks experimental evidence and is controversial(American Speech-Language Hearing Association, 1995). The treatmentinvolves listening to modulated music with specific frequencieselectively filtered. Three machines (Audiokinetron, BGC Audio ToneEnhancer/Trainer, AudioScion) are available for AIT treatments(Barkell & Malgeri, l99). Safety concerns about the equipmenthave resulted in the U. S. Federal Food and Drug Administrationdirecting that additional research on the AIT devices be conductedprior to continued distribution. The safety concerns are about thespecifications of the machines and their effects on the userÕshearing ability. The American Speech-Language Hearing Associationsupports the need for this research (American Speech-Language HearingAssociation, 1995). Another problem with AIT is no training standardsand guidelines for AIT trainers.
Other treatments for hyperacusis include biofeedback andrelaxation techniques (American Speech-Language Hearing Association,1995). Meyer Rosen, a hyperacusis sufferer, has tried fooddesensitization, exposure of nasal passages to essential oils,neurolinguistic training, rehydration of mucous membanes, correctionof head-forward posture, scalp and body acupuncture, progressiverelaxation of the temporomandibular joint musculature by anorthopedic mandibular repositioning device, and the use of an earplugprescription. After much study Meyer developed an acupuncturetreatment called Reflex-Correspondence Training (Rosen, 1995). All ofthese treatments lack scientific evidence.
All aspects of hyperacusis need future research. There appear tobe many causes for hyperacusis. The physiological and psychologicalfactors need to be determined as causing or contributing to thedisorder. New treatments need to be discovered, and the presenttreatments need to be placed on a scientific basis. At the presenttime hyperacusis sufferers are receiving treatments with the hopethat help will be obtained, and permanent damage will not result totheir auditory systems.
For a referral to an American Speech-Language Hearing Association(ASHA) certified audiologist in your area, call ASHSÕs InformationResource Center at (800) 638-8225. Additional information can beobtained by contacting The Hyperacusis Network, write or call TheHyperacusis Network, 444 Edgewood Drive, Green Bay, WI 54302 (414)468-4667.
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American Psychiatric Association (1994). Diagnostic andStatistical 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 asymptom of 5-hydroxytryptamne (5-HT) dsyfunction?. The Journal ofLaryngology 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 DevelopmentalDisabilities, 31(1), 66-70.
Borsel, J. V., Curfs, L. M., & Fryns, J. P. (1997).Hyperacusis in Williams syndrome: A sample survey study. GeneticCounseling, 8(2), 121-126.
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Moller, A. R. & Szczepaniak, W. S. (1995). Effects ofL-baclofen and D-baclofen on the auditory system: A study ofclick-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--apainful, ultrasensitivity to normal sounds (letter to the editor).American Journal of Acupuncture, 23(1), 74-76.
Sanchez, L. & Stephens, D. (1997). A tinnitus problemquestionnaire in a clinic population. Ear & Hearing, 18,210-217.
Schwade, S. (1995). Shedding light on supersensitive hearing: Whatto do when every small noise sounds like the big bang. Prevention,47(8), 90-96.