AJA Review Article A Review of Hyperacusis and Future Directions: Part I. Definitions and Manifestations Richard S. Tyler,a Martin Pienkowski,b Eveling Rojas Roncancio,a Hyung Jin Jun,a Tom Brozoski,c Nicolas Dauman,d Claudia Barros Coelho,a Gerhard Andersson,e,f Andrew J. Keiner,a Anthony T. Cacace,g Nora Martin,a and Brian C. J. Mooreh Purpose: Hyperacusis can be extremely debilitating, and at Results: Hyperacusis encompasses a wide range of present, there is no cure. We provide an overview of the reactions to sound, which can be grouped into the field, and possible related areas, in the hope of facilitating categories of excessive loudness, annoyance, fear, and future research. pain. Many different causes have been proposed, and it will Method: We review and reference literature on be important to appreciate and quantify different subgroups. hyperacusis and related areas. We have divided the Reasonable approaches to assessing the different forms of review into 2 articles. In Part I, we discuss definitions, hyperacusis are emerging, including psychoacoustical epidemiology, different etiologies and subgroups, and measures, questionnaires, and brain imaging. how hyperacusis affects people. In Part II, we review Conclusions: Hyperacusis can make life difficult for many, measurements, models, mechanisms, and treatments, forcing sufferers to dramatically alter their work and social and we finish with some suggestions for further habits. We believe this is an opportune time to explore research. approaches to better understand and treat hyperacusis. yperacusis can be devastating for those who suf- refereed publications, books, and conference proceedings. fer from it. This review is intended to clarify what We highlighted what we believe are key issues that are im- H is known at present about hyperacusis and its portant to move forward, sometimes even drawing from underlying mechanisms to focus research and to promote areas not normally associated with hyperacusis. In Part I, the development of new treatments. A group of researchers we set the background by discussing terminology, preva- and clinicians with a variety of backgrounds was gathered lence, different etiologies and subgroups, related symptoms, by the senior author. Several topic areas relevant to hyper- and imaging studies. This sets the stage for Part II, in which acusis were identified. We were not interested in focusing we discuss mechanisms, models, and treatments. We pro- on clinical trials. Hyperacusis covers many disciplines, and vide a broad perspective on many areas related to hyper- because the terminology is not standardized, we wanted acusis. Our intent is to provide a comprehensive review that freedom to explore areas we thought were relevant and will motivate and assist those interested in developing future important. We used our diverse backgrounds to explore treatments. aUniversity of Iowa, Iowa City Definitions bSalus University, Elkins Park, PA c Numerous descriptions of hyperacusis have been put Southern Illinois University School of Medicine, Springfield forward, but there are no universally accepted definitions. dUniversity of Poitiers, France e “Hyper” implies excessive, perhaps abnormal, and “acusis” Linköping University, Sweden fKarolinska Institute, Stockholm, Sweden represents sound. We begin by reviewing the ways authors gWayne State University, Detroit, MI have described and defined this abnormal, excessive response hUniversity of Cambridge, England to sound. Correspondence to Richard S. Tyler: [email protected] First, it is relevant to note that the perception of high- Editor and Associate Editor: Larry Humes intensity sounds by listeners with normal hearing, without “ ” Received February 17, 2014 complaints of hyperacusis, has been described as a tickle Revision received July 2, 2014 Accepted July 24, 2014 Disclosure: The authors have declared that no competing interests existed at the DOI: 10.1044/2014_AJA-14-0010 time of publication. 402 American Journal of Audiology • Vol. 23 • 402–419 • December 2014 • © American Speech-Language-Hearing Association Downloaded From: http://aja.pubs.asha.org/ by ASHA Publications, Karen Anderson on 01/21/2015 Terms of Use: http://pubs.asha.org/ss/Rights_and_Permissions.aspx (von Bekesy, 1936; Silverman, Harrison, & Lane, 1946), a “hyperesthesia dolorosa”; Krassnig, 1924; cited by Perlman, “discomfort” (Silverman et al., 1946; Wegel, 1932), and a 1938), misophonia (a dislike; Jastreboff & Jastreboff, 2003), “pain” (Cox, 1981). In the following discussion, we focus annoyance (Dauman & Bouscau-Faure, 2005), and fear on descriptions in which the authors believe the responses (Blomberg, Rosander, & Andersson, 2005). A specific ques- are abnormal. tion on fear was included in a questionnaire to quantify Some have defined hyperacusis as a heightened hyperacusis by Khalfa et al. (2004). Another definition of awareness of sounds (Phillips & Carr, 1998). Others have hyperacusis includes pain (Chemtob, Roitblat, Hamada, referred to an abnormally strong response to moderate Carlson, & Twentyman, 1988). sound (Gold, Frederick, & Formby, 1999), a pathological To summarize, definitions and descriptions of hyper- auditory hypersensitivity (Khalfa et al., 2004), an increased acusis have included heightened awareness, hypersensitivity, auditory sensitivity (Hébert, Fournier, & Noreña, 2013), loudness, discomfort, hyperresponsiveness, intolerance, a noise sensitivity (Stansfeld, 1992; Taylor, 1984), an audio- phonophobia, irritability, misophonia, annoyance, fear, and sensitivity (Gordon, 1986), a soft sound sensitivity, or a pain. So what is a reasonable way to approach and define select sound sensitivity (McKenzie, 2012; Neal & Cavanna, hyperacusis? Phillips and Carr (1998) commented on this 2012). confusion of terminology. They noted that the same terms Traditionally in psychoacoustics, the term sensitivity are often used to describe different sensations, probably refers to hearing threshold. Thus, if one has hearing thresh- with different underlying mechanisms. Conversely, different olds that are better than normal (below 0 dB HL), one is terms are sometimes used to describe similar sensations. hypersensitive. Hyperacusis is not usually associated with Dauman and Bouscau-Faure (2005) also commented that such hypersensitivity. However, very little information has the terminology describing the annoyance caused by every- been published about this, in part perhaps because hearing day sounds is misleading. We agree with Phillips and Carr thresholds below 0 dB HL are seldom measured, and many that the emotional aspects of hyperacusis should be treated audiometers do not allow the measurement of thresholds distinctly from its loudness aspects. The definitions of below −10 dB HL. We discourage the use of the term hyper- hyperacusis should be clear, distinct, and easy to interpret sensitivity to refer to hyperacusis. and recognize by different professions and by the general Hyperacusis has also been described as a disturbed public. loudness function (Phillips & Carr, 1998). Sounds that are We suggest that the simplest and clearest distinction perceived as moderately loud by people with normal hearing of the different forms of hyperacusis should focus on loud- and without hyperacusis are perceived as very loud by ness, annoyance, fear, and pain. We believe that these someone with hyperacusis. Another emphasis has been four categories capture the general perceptions and associ- on tolerating sounds. Hyperacusis has been referred to ated reactions, and we distinguish between them in a mean- as an intolerance (Hébert, Paiement, & Lupien, 2004), as ingful fashion. People with hyperacusis can experience an unusual intolerance to ordinary environmental sounds these different reactions singly or in combination. The loud- (Khalfa et al., 2004; Vernon, 1987), or as a sound intolerance ness percept could be considered as a basic primary psycho- problem (Khalfa et al., 2004). acoustical response, and the annoyance and fear could be Another definition involves discomfort (Krassnig, 1924). considered as self-report emotional reactions. Pain hyper- Hyperacusis is a discomfort for sounds that would be ac- acusis might be one or the other, or both. In this article, we ceptable to most normally hearing people (Khalfa et al., use these specific terms when authors are precise about what 2004). Hyperacusis is also a hyperresponsiveness to sound they are referring to; otherwise, we use the general term stimuli (Song et al., 2013) or a hyperresponsiveness to hyperacusis. noise (Dauman & Bouscau-Faure, 2005). An abnormally low tolerance for sound levels (Johnson, 1999), a loudness tolerance problem (Stephens, 1970), and sound intolerance Loudness Hyperacusis (Formby & Gold, 2002) have also been emphasized. Although Early discussions of the perception of loudness by this suggests that hyperacusis is not being able to tolerate hearing-impaired people included a category of over- sounds, most people have no choice but to tolerate loud recruitment, whereby the loudness discomfort level (LDL) sounds, even though they might be annoyed by them. We or (interchangeably) the uncomfortable loudness level (ULL) have also observed clinically that some hyperacusis patients —defined as the lowest sound level judged by the listener mention that loud sounds can be distorted. to be uncomfortably loud—was lower than for individuals Several authors have argued that it is critical to high- with normal hearing (Fowler, 1965). We consider loudness light the emotional