Human exposures and their associated hearing loss profiles: Music industry professionals

Exposure to sounds of sufficient level and duration has been shown to cause adverse auditory effects in humans, known categorically as noise induced hearing disorders (NIHDs). Noise induced hearing loss (NIHL) is the most commonly discussed and researched condition due in part to the high prevalence in large populations such as military personnel and industrial workers. Tinnitus, hyperacusis, diplacusis, and dysacusis are other auditory disorders which can result from excessive sound exposure. When music is the dominant sound source, the resultant auditory conditions are termed music induced hearing disorders (MIHD). The marked increase in prevalence of MIHDs in music industry professionals as compared to the general population (Royster , 1991; Schink , 2014; Stadio , 2018) indicates that music should be considered a potentially damaging stimulus. This topic has been the subject of investigation and academic curiosity since the advent of amplified music [for example, see Rintelmann and Borus, (1968)].

The professional music and entertainment industry can be considered a uniquely vulnerable population to MIHDs due to the high probability for regular exposure to sound levels known to be hazardous to hearing, the integral relationship between auditory health and primary occupational performance, and the current status as an unregulated industry in the United States. Key subpopulations with unique considerations include performing musicians, audio engineers, recording personnel, music educators and students, and performance support staff. Additionally, those working in a music-dominated environment, including ushers, security personnel, and food service staff may be exposed to comparably high sound levels. These exposures are significant enough to treat MIHDs as occupational diseases (Emmerich , 2008). Though beyond the scope of this paper, it bears mention that audience members can be exposed to high levels of sound in live entertainment settings since their own exposure is directly affected by the actions of the performers, technical crew, and support professionals.

Music differs from noise in both acoustical and psychophysical qualities. In acoustical comparison with industrial noise, music tends to have a higher crest factor, higher frequency correlation (less broadband noise elements), and higher proportion of lulls or downtime. Several authors have suggested that the current modeling of auditory risk via industrial damage-risk criteria may not be adequate to understand music, which inherently has more spectral, temporal, and dynamic fluctuation than steady-state industrial noise (Fligor and Cox, 2004; Strasser , 1999; Turunen-Rise , 1991). Unfortunately, the lack of longitudinal studies of music exposure paired with exposure data results in inadequate data available to create a damage-risk criterion which is specific to music exposure. Even within subgroups, variability in occupational settings, work schedules, and dominate sound sources further complicates risk criteria generalizations of music industry professionals. Notwithstanding, the literature is clear that music professionals are often exposed to potentially damaging sound levels, and one small study found similar hearing loss in orchestral musicians as would be predicted for individuals exposed to industrial noise (Szibor , 2018; Strasser , 2008; Russo , 2013; Zhao , 2009). Further research is necessary to better model risk for performing musicians and individuals working in music dominated environments.

Studies on MIHDs and hearing loss have been conducted in the music industry for decades; however, sample sizes are generally small and the highly variable sound exposure between performance settings and genres can impede generalized conclusions and development of clinical recommendations. Since individual sound exposure to sound can vary considerably between different performers, settings, and supporting personnel roles, it is no surprise that the reported incidence of MIHDs within the music industry varies widely from 30% to 74% (Zhao , 2009; Stadio, 2018, Kähäri, , 2003, Halevi-Katz , 2015). One of the largest studies to date found professional musicians to have a 57% higher adjusted risk of tinnitus than the general population (Schink, , 2014). Despite this wide range of prevalence, it remains clear that MIHDs are prevalent regardless of a professional's primary musical genre and role.

The hearing loss profile of music industry professionals is generally comparable to that of other noise-exposed populations. This may be attributed to the similarities between the macro acoustic qualities of music and what is generally considered to be noise, and also attributed to the compound nature of sound exposure: music is rarely if ever the only sound to which a musician will be routinely exposed. As with NIHL, music induced hearing loss (MIHL) is characterized by a gradual loss of auditory threshold sensitivity in a high-mid frequency region of hearing, with the classic presentation of a sensorineural hearing loss “notch” centered in the 3000–6000 Hz region (Royster , 1991). As can be expected with noise-induced populations, music industry professionals who are exposed to hazardous sound levels for longer periods of time demonstrate a greater prevalence of an audiometric notch (Stadio , 2018, Malyuk, 2018). In the setting of a diffuse soundfield, MIHL is typically bilateral and symmetric in nature. However, performing musicians demonstrate a higher prevalence of asymmetric hearing loss attributable the physical laterality characteristics of their primary instrument and location within an ensemble (Chasin, 1996). For instance, the violin disproportionately exposes the player's left ear to the instrument's direct sound while the flute's sound is weighted to the player's right ear (Rosanowski and Eysholdt 1996). Positioning near or adjacent to more intense instruments (drums, horn sections) or sound sources (electric instrument amplifiers, sound reinforcement speakers, stage monitor speakers) within an ensemble can similarly lead to significant asymmetric exposures reflected in the laterality of a music professional's auditory symptoms (Chasin, 1996).

Reduced auditory thresholds in the extended high frequency (EHF) audiometric range (>8000 Hz) has been suggested to be a more sensitive indicator to auditory damage as compared to the conventional audiometric range (125–8000 Hz) (Mehrparvar , 2014). Though the EHF literature is limited within music populations, preliminary studies show statistically significant differences between the EHF thresholds of musicians when compared with age-matched control groups (Kazkayasi , 2006; Malyuk, 2018). This area of research should not be discounted when considering the establishment of recommendations for the clinical test battery as musicians routinely utilize EHF hearing for pitch and timbre discrimination, as well as for critical listening roles (Barthet , 2010; Grey and Gordon, 1978; Yokoyama , 2017).

For music industry professionals, MIHDs can yield career-ending side effects due to high sound level exposure. MIHDs encompass numerous related and often coexisting auditory conditions including hearing loss, tinnitus, hyperacusis, diplacusis, and dysacusis. The ability to critically listen to and analyze music is, in most cases, crucial to a musical career. A general respect for advanced auditory abilities can be observed throughout the culture of music professionals, and indeed acknowledgement that one has a “good ear” can be considered a most high compliment exchanged amongst musicians. A performing musician with hearing loss may have either actual or perceived difficulty playing in concert with other musicians, a primary job function. The actual impact of hearing loss will vary as a factor of the individual's work setting and role as well as the severity of the hearing loss. For example, the development of mild MIHL may represent a career-limiting ailment to a record mastering engineer or audio restoration/restoration/archivist, but the same hearing loss may have limited impact on the livelihood of a touring rock music performer or stage crewman. Indeed, most live music sources are of sufficient level to minimize the perceptual impact of even a moderate sensorineural hearing loss from an audibility standpoint (Chasin, 1996).

While music professionals may be able to “ear train” and ultimately learn to perform their respective role with hearing loss, other MIHDs often present a more devastating vocational impact. Of these disorders, tinnitus and hyperacusis are the most prevalent and can occur even in the absence of measurable NIHL (Schmidt , 2011; Toppilla , 2011). Chronic bothersome tinnitus may dramatically reduce one's trust in their auditory perceptual abilities when critical listening is required for their work, and can inhibit both focus and personal enjoyment for performance-based roles (Vogel , 2014). Hyperacusis severely limits one's capacity to tolerate high level sound sources which are inherent in the majority of professional music settings, thereby hindering participation in rehearsals, performances, studio sessions, and support work within venues (Kähäri , 2001). While less common than tinnitus and hyperacusis, diplacusis (difference in pitch perception between ears) and dysacusis (perception of distorted sound, particularly in one ear) erode one's sense of pitch stability. Pitch perception is important for tasks requiring critical listening (editing, mixing, mastering, etc.) and abnormalities in this facility are a significant hindrance towards the performance of continuous pitch instruments (bowed strings, voice, tympani, etc.). Studies which have included diplacusis and dysacusis (often referred to as distortion) have reported relatively low incidence across musicians (Laitinen and Poulsen, 2008; Stadio , 2018). Though somewhat uncommon, disorders of pitch perception can be career-ending conditions for music professionals. Beyond these auditory perceptual impacts, the development of MIHDs creates a psychological barrier for a music industry professional; the individual who no longer feels comfortable relying on their “ear” may feel unable to maintain a career in music.

There exist employment and employability considerations which are difficult to quantify in the music industry. Anecdotally, many music professionals with MIHDs choose not to seek care, may not report auditory disorders to employers, and may not seek workplace accommodations out of fear of being perceived as unemployable. Even when simple accommodations or treatments may ameliorate the impairment, a music professional may hide their hearing disorder from employers and the public. Although this culture of silence shows signs of changing with more prominent musicians publicly acknowledging their ailments, there exists a conflict of interest stacked against care-seeking when MIHDs are perceived as an unspoken professional risk. Further complicating the situation, it is not possible to track the rate of career abandonment secondary to MIHDs considering that the individual's voice is no longer part of the greater community's discussion. In short, the public and community opinion is most influenced by those with sufficient career stability to be recognizable, influential, and not risk their own employability when they do speak up.

The quality of life impacts of MIHD are difficult to isolate from vocational impacts for the musician, as an individual's sense of drive and purpose can be interlaced with their involvement in their chosen profession. This interplay can be heightened in the creative arts as the lines between vocation and avocation may be ill-defined. To date, very few studies have been completed in this area. The limited literature in this area indicate stress is associated with diminished ability to relax and difficulty sleeping (Kähäri, , 2003). Anecdotally, musicians clinically report high levels of stress associated with MIHDs. Further investigation into this aspect of the whole-person impacts of MIHDs is needed as insights would aid in the triage and treatment of music professionals.

Traditional interventions designed to mediate acquired hearing damage leverage the reduction of an individual's exposed level, duration of exposure, or both. In many applications, behavioral adjustments can be the most effective and efficient. Technological methods to reduce exposure level include personal-wear products (generically fit hearing protection, custom filtered uniform-attenuation earplugs, and custom molded in-ear monitors) as well as externally deployed products (acoustic barriers, sound absorptive devices, recording studios, and other specially designed spaces for the control and routing of sound signals). Certainly, many musicians use filtered earplugs, and these have made a significant impact in helping to protect hearing across the population of musicians. However, though technology has improved significantly in the last several decades to afford higher-fidelity listening and greater acoustic control with these devices, none are without compromise of the original acoustic signal (Santucci, 2009). Even the best interventions require the user to adjust and “ear-train” to their proper use (Portnuff, 2018).

Noise controls, including engineering and administrative controls, are often touted as the most effective interventions for hearing loss prevention and can be employed to reduce the level and/or duration of an individual's exposure (Franks and Merry, 1996). Though specific interventions were invented for industrial environments, the strategies which are deployed in the music industry are based on the same core concepts of minimizing sound at the source, reducing non-essential exposures, and cross-analysing job responsibilities with assumed risks. For music professionals, the options are numerous and include reduction of personal practice time, deconstruction of ensemble rehearsals into smaller sectional groups, and strategic programming of performances (Chasin, 1996). Despite these many methods currently deployed for hearing conservation the use rate of current hearing protection device options is markedly low among musicians (Cunningham , 2006; Laitinen, 2005; Huttunen , 2011), and practical use of barriers and shields for engineering controls within such populations as symphonic musicians have yet to be supported by evidence-based research (Kwiatkowski , 1986; Wenmaekers , 2017). While it is true that many of these traditional level-reduction and duration-reduction schemes have practical and even musical benefits—the discussion of which exceed the intended depth of this paper—all necessitate an alteration to the perception of the resultant music, as well as to the very experience of music-making. In short, musicians have significant real and perceived barriers to reducing their individual sound exposure through both sound level controls and hearing protective devices.

The emergence of pharmaceutical interventions designed to prevent hearing loss from high sound exposures in recent years has been a hot topic in research literature and in clinical trials (Sha and Schacht, 2017). Availability of a pharmaceutical intervention with proven efficacy at reducing the adverse effects of sound exposure on the auditory system would constitute a notable change in the available hearing conservation options for this population. Reduction of risk equates a reduction in individual reliance on engineering controls, traditional personal-wear products, and externally deployed interventions. Ultimately, a reduction of barriers-to-entry and auditory compromises may increase end-user acceptance of hearing conservation interventions. The prospect is alluring; perform this one innocuous action—take a pill, for instance—and the music professional proceed otherwise carefree with no behavior or acoustic modification in the name of safety. Though this scene correlates most vividly with the rock and roll image of popular-genre music performers, it may have the most pronounced career-saving implications for classical performers and musicians in academic settings. MIHDs are common with individuals in these categories, and (perhaps causatively at least in part) they tend to have less access to viable technological solutions which acceptably address their complex listening needs with dynamic and informationally dense repertoire. In the case of academically based musicians, the simultaneous educational and administrative duties such as classroom management construct unique barriers to the adoption of traditional hearing conservation interventions.

A primary concern with any new intervention is misinformation, or the failure to properly educate the target population on any potential limitations. Should a particular PIHL provide a degree of protection without complete immunity from MIHDs, this distinction must be made clear in fact and magnitude to the end-user. Otherwise, over-reliance or trust in a particular PIHL could lead to additional risk-taking behavior, thereby negating the potential benefits. As music industry professionals are not a homogenous group and are widely spread across the population, significant public health campaigns may be required to educate this population about MIHDs and to motivate them to take a medication or supplement. Any public health campaigns should consider well established models of health behavior (e.g., Health Belief Modeling, or the Theory of Planned Behavior and Reasoned Action), which have been shown to be functional in the area of MIHD prevention (Gilles and Paul, 2014; Portnuff , 2011).

The disruptive nature of PIHL has the potential to degrade the growing but delicate culture of hearing wellness awareness and professional caution in the music community. The result of decreased perceived risk may be complacency, and with it the abandon of traditional interventions and methods for hearing conservation. Even if pharmaceutical interventions are effective at preventing MIHDs, reductions in sound exposure will always be the most effective preventative steps. Furthermore, a decrease in caution by the performers and technical support professionals could result in increased functional exposure for the contingent population: audience members. Necessary actions to combat this risk are twofold: educate performers regarding continued need to consider the audience's safety, and educate audience members to the risk of MIHDs and the availability of PIHL and traditional forms of MIHD prevention.

Finally, the attractions of a simple single pill solution could be its greatest weakness. The common logic of “if one is good, then two is better” should be factored into the formulation and end-user informational materials to avoid unexpected consequences of over- or mis-use. Some research in otoprotectants has identified significant dose-dependent effects, where both doses which are too low or too high are ineffective at preventing hearing loss (Kil , 2017) If PIHL are available over-the-counter, individuals should be well educated that even over-the-counter supplements are not risk-free, and that overuse can be harmful (Catlin , 2015). Care must be taken to ensure that public health narratives are specific about dosing and the risks of overdosing (Wu and Anh, 2010). It is a common cultural narrative that those in professional music fields engage in self-medication for reduction for music performance anxiety and/or social-recreational reasons (Hernández , 2018). Though evidence is limited on the rate of licit or illicit drug use in musicians [for discussion see Miller and Quigley (2012)] there is substantial anecdotal evidence of this trope and the consequences of which should be considered. Consideration should also be given to the risk of polypharmacy with lifestyle drugs, prescription medications, and illicit drugs.

Music industry professionals represent a vulnerable population to hearing disorders, and participate in a field that has many individual and institutional barriers to traditional hearing conservation interventions. PIHL would be a disruptive new approach which carries with it the potential to address many of these barriers, yet there are significant considerations which should be addressed to avoid unintended consequences. Further research pertaining to the damage risk criteria of music, current barriers to use of traditional hearing conservation interventions within the music industry, as well as the public health impacts of PIHL are indicated.