Ebook Clinical assessment of voice (2E): Part 2

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(BQ) Part 2 book “Clinical assessment of voice” has contents: Endocrine function, respiratory dysfunction, laryngeal papilloma, spasmodic dysphonia, vocal fold paresis and paralysis, voice impairment, disability, handicap, and medical-legal evaluation,… and other contents. 15 Hearing Loss in Singers and Other Musicians Robert Thayer Sataloff, Joseph Sataloff, and Brian McGovern Singers and other musicians depend on good hearing to match pitch, monitor vocal quality, and provide feedback and direction for adjustments during performance The importance of good hearing among performing artists has been underappreciated Although well-trained musicians are usually careful to protect their voices or hands, they may subject their ears to unnecessary damage and thereby threaten their musical careers The ear is a critical part of the musician’s “instrument.” Consequently, it is important for singers to understand how the ear works, how to take care of it, what can go wrong with it, and how to avoid hearing loss from preventable injury Causes of Hearing Loss The classification and causes of hearing loss have been described in detail in standard textbooks of otolaryngology and previous works by the authors,1,2 and they will be reviewed only briefly in this chapter Hearing loss may be hereditary or nonhereditary, and either form may be congenital (present at birth) or acquired There is a common misconception that hereditary hearing loss implies the presence of the problem at birth or during childhood In fact, most hereditary hearing loss occurs later in life All otolaryngologists know families whose members begin to lose their hearing in their third, fourth, or fifth decade, for example Otosclerosis, a common cause of correctable hearing loss, often presents when people are in their 20s or 30s Similarly, the presence of deafness at birth does not necessarily imply hereditary or genetic factors A child whose mother had rubella during the first trimester of pregnancy or was exposed to radiation early in pregnancy may be born with a hearing loss This is not of genetic etiology and has no predictive value for the hearing of the child’s siblings or future children Hearing loss may occur because of problems in any portion of the ear, the nerve between the ear and the brain, or the brain Understanding hearing loss requires a basic knowledge of the structure of the human ear Anatomy and Physiology of the Ear The ear is divided into major anatomical divisions: the outer ear, the middle ear, and the inner ear The outer ear has parts: (1) the trumpet-shaped apparatus on the side of the head, the auricle or pinna, and (2) the tube leading from the auricle into the temporal bone, the external auditory canal The opening of the tube is called the meatus The middle ear is a small cavity in the temporal bone in which auditory ossicles, the malleus (hammer), incus (anvil), and stapes (stirrup), form a bony bridge from the external ear to the inner ear (Figure 15–1) This bony bridge is held in place by muscles and ligaments The tympanic membrane or eardrum stretches across the inner end of the external ear canal, separating the outer ear from the middle ear The middleear chamber normally is filled with air and connects to the nasopharynx through the eustachian tube The eustachian tube helps to equalize pressure on both sides of the eardrum The inner ear is a fluid-filled chamber divided into parts: (1) the vestibular labyrinth, which functions 257 258 Clinical Assessment of Voice Figure 15–1.  Cross section of the ear The semicircular canals are part of the balance system as part of the body’s balance mechanism, and (2) the cochlea, which contains thousands of minute, sensory, hairlike cells (Figure 15–2) responsible for beginning the electrical stimulation to the brain The organ of Corti functions as the switchboard for the auditory system The eighth cranial (acoustic) nerve leads from the inner ear to the brain, serving as the pathway for the electrical impulses that the brain will interpret as sound Sound begins from a source that creates vibrations or sound waves in the air somewhat similar to the waves created when a stone is thrown into a pond The pinna collects these sound waves and funnels them down the external ear canal to the eardrum The sound waves then cause the eardrum to vibrate These vibrations are transmitted through the middle ear over the bony bridge or ossicular chain formed by the malleus, incus, and stapes The vibrations in turn cause the membranes over the openings to the inner ear to vibrate, causing the fluid in the inner ear to be set in motion The motion of the fluid in the inner ear displaces the hair cells, which in turn excite the nerve cells in the organ of Corti, producing electrochemical impulses that are transmitted to the brain along the acoustic nerve As the impulses reach the brain, we experience the sensation of hearing Establishing the Site of Damage in the Auditory System The cause of a hearing loss, like that of any other medical condition, is determined by obtaining a detailed history, making a thorough physical examination, and performing various clinical and laboratory tests An audiogram provides a “map” of hearing and details the levels at which sound is detected at various frequencies When a hearing loss is identified, an attempt is made to localize the point along the auditory pathway where the difficulty has originated Every attempt to determine whether the patient’s hearing loss is conductive, sensorineural, central, functional, or a mixture of these is made However, sometimes these distinctions can be difficult to make In particular, it is very difficult to distinguish sensory from neural lesions Details of the otologic history, physical examination, and test protocols are detailed in many otolaryngology texts Medical evaluation of a patient with a suspected hearing problem includes a comprehensive history; complete physical examination of the ears, nose, throat, head, and neck; assessment of the cranial nerves, including testing the sensation in the external auditory canal (Hitselberger sign); audiogram (hear- 15.  Hearing Loss in Singers and Other Musicians Figure 15–2.  Cross-section of the organ of Corti A Low magnification B Higher magnification 259 260 Clinical Assessment of Voice ing test); and other tests, as indicated Recommended additional studies may include computed tomography (CT), magnetic resonance imaging (MRI), dynamic imaging studies such as single-photon emission computed tomography (SPECT), position emission tomography (PET), specialized hearing tests such as brainstem evoked response audiometry (ABR or BERA), electronystagmography (ENG), computerized dynamic posturography (CDP), otoacoustic emissions, immittance measures, central auditory processing testing, and a variety of blood tests for the many systemic causes of hearing loss All patients with hearing complaints deserve a thorough examination and comprehensive evaluation to determine the specific cause of the problem and to rule out serious or treatable conditions that may be responsible for the hearing impairment Contrary to popular misconceptions, not all cases of sensorineural hearing loss are incurable So “nerve deafness” should be assessed with the same systematic vigor and enthusiasm as conductive hearing loss forations usually not cause a great deal of hearing impairment Hearing loss from middle ear dysfunction is the most common cause of conductive hearing loss and may cause a hearing decrease of up to 60 decibels It may occur in many ways The middle ear may become filled with fluid because of eustachian tube dysfunction The fluid restricts free movement of the tympanic membrane and ossicles, thereby producing hearing loss Middle-ear conductive hearing loss may also be caused by ossicular abnormalities These include fractures, erosion from disease, impingement by tumors, congenital malformations, and other causes However, otosclerosis is among the most common This hereditary disease afflicts the stapes and prevents it from moving in its normal piston-like fashion in the oval window Hearing loss from otosclerosis can be corrected through stapes surgery, a brief operation under local anesthesia, and it is usually possible to restore hearing Conductive Hearing Loss The word sensorineural was introduced to replace the ambiguous terms perceptive deafness and nerve deafness The term sensory hearing loss is applied when the damage is localized to the inner ear and auditory nerve The cochlea has approximately 15 000 hearing nerve endings (hair cells) Those hair cells, and the nerve that connects them to the brain, are susceptible to damage from a variety of causes Neural hearing loss is the correct term to use when the damage is in the auditory nerve proper, anywhere between its fibers at the base of the hair cells and the auditory nuclei This range includes the bipolar ganglion of the eighth cranial nerve Other common names for this type of loss are nerve deafness and retrocochlear hearing loss These names are useful if applied appropriately and meaningfully, but too often they are used improperly Although at present it is common practice to group together both sensory and neural components, it has become possible through advanced diagnostic techniques to attribute a predominant part of the damage, if not all of it, to either the inner ear or the nerve This separation is advisable because the prognosis and the treatment of the kinds of impairment differ For example, in all cases of unilateral sensorineural hearing loss, it is important to distinguish between a sensory and neural hearing impairment, because the neural type may be due to a tumor called an acoustic neuroma, which could become life-threatening if left untreated Cases that we cannot identify as either sensory or neural and cases in which there is damage in both regions we classify as sensorineural In cases of conductive hearing loss, sound waves are not effectively transmitted to the inner ear as a result of some mechanical defect in the outer or middle ear The outer and middle ear normally enhance and transfer sound energy to the inner ear or cochlea In a purely conductive hearing loss, there is no damage to the inner ear or the neural pathway; rather, the damage lies in the external canal or the middle ear Patients diagnosed as having conductive hearing loss have a much better prognosis than those with sensorineural loss, because modern techniques make it possible to cure or at least improve the vast majority of cases in which the damage occurs in the outer or middle ear Even if they are not improved medically or surgically, these patients stand to benefit greatly from a hearing aid, because what they need most is amplification They are not bothered by distortion and other hearing abnormalities that may occur in sensorineural hearing losses Some more common types of conductive hearing loss may result from a complete or partial blockage of the outer ear, which will interfere with sound transmission to the middle ear Outer ear problems include birth defects, total occlusion of the external auditory canal by wax, foreign body (eg, a piece of cotton swab or ear plug), infection, trauma, or tumor Large perforations in the tympanic membrane may also cause hearing loss, especially if they surround the malleus However, relatively small, central per- Sensorineural Hearing Loss 15.  Hearing Loss in Singers and Other Musicians There are various and complex causes of sensorineural hearing loss, but certain features are characteristic and basic to all of them Because the histories obtained from patients are so diverse, they contribute more insight into the etiology than into the classification of a cause Sensorineural hearing loss often involves not only loss of loudness but also loss of clarity The hair cells in the inner ear are responsible for analyzing auditory input and instantaneously coding it The auditory nerve is responsible for carrying this complex coded information Neural defects such as acoustic neuromas (benign tumors of the auditory nerve) are frequently accompanied by severe difficulties in discriminating sounds and words effectively, although the actual hearing threshold for differences in sounds may not be greatly affected Sensory deficits in the cochlea are often associated with distortion of sound quality, distortion of loudness (loudness recruitment), and distortion of pitch (diplacusis) Diplacusis poses particular problems for musicians, because it may make it difficult for them to tell whether they are playing or singing correct pitches This symptom is also troublesome to conductors Keyboard players and other musicians whose instruments not require critical tuning adjustments compensate for this problem better than singers, string players, and the like In addition, sensorineural hearing loss may be accompanied by tinnitus (noises in the ear) and/or vertigo However, it is possible to have these auditory symptoms and not demonstrate a hearing loss on a routine audiogram Hearing loss may be present at frequencies between or above those usually tested and can be detected with special audiometers that test all (or nearly all) of the frequencies from 125 to 12 000 Hz Special ultrahigh-frequency audiometers are available commercially and can measure hearing thresholds up to 20 000 Hz An evaluation of this hearing range can show damage that could not be detected at routinely tested frequencies Sensorineural hearing loss may be due to a great number of conditions, including exposure to ototoxic drugs (including a number of antibiotics, diuretics, and chemotherapy agents), hereditary conditions, systemic diseases, trauma, and noise, among other causes Most physicians recognize that hearing loss may be associated with a large number of hereditary syndromes2,3 involving the eyes, kidneys, heart, or any other body system; but many are not aware that hearing loss also accompanies many, very common systemic diseases Naturally, these occur in musicians as well as others The presence of these systemic illnesses should lead physicians to inquire about 261 hearing and to perform audiometry in selected cases Problems implicated in hearing impairment include Rh incompatibility, hypoxia, jaundice, rubella, mumps, rubeola, fungal infections, meningitis, tuberculosis, sarcoidosis, Wegener granulomatosis, vasculitis, histiocytosis X, allergy, hyperlipoproteinemia, syphilis, hypothyroidism, hypoadrenalism, hypopituitarism, renal failure, autoimmune disease, coagulopathies, aneurysms, vascular disease, multiple sclerosis, infestations, diabetes, hypoglycemia, cleft palate, and others.2 Prolonged exposure to very loud noise is a common cause of hearing loss in our society Noiseinduced hearing loss is seen most frequently in heavy industry However, occupational hearing loss caused by musical instruments is a special problem, as discussed below Mixed Hearing Loss For practical purposes, a mixed hearing loss should be understood to mean a conductive hearing loss accompanied by a sensory, neural (or a sensorineural) loss in the same ear However, the clinical emphasis is on the conductive hearing loss, because available therapy is so much more effective for this disorder Consequently, the otologic surgeon has a special interest in cases of mixed hearing loss in which there is primarily a conductive loss complicated by some sensorineural damage In a musician, curing the correctable component may be sufficient to convert hearing from unserviceable to satisfactory for performance purposes Functional Hearing Loss Functional hearing loss occurs as a condition in which the patient does not seem to hear or to respond, yet the handicap is not caused by any organic pathology in the peripheral or central auditory pathways The hearing difficulty may have an entirely psychological etiology, or it may be superimposed on some mild organic hearing loss, in which case it is called a functional or a psychogenic overlay Often, the patient has normal hearing, but the secondary gain from a hearing loss, even if it is not organic, motivates the patient to behave as though he or she has a legitimate hearing loss In some cases, the patient may not even realize that the loss is nonorganic A careful history usually will reveal some hearing impairment in the patient’s family or some personally meaningful reference to deafness that generated the patient’s psychogenic hearing loss The important challenge for the clinician in such a case is to classify the condition 262 Clinical Assessment of Voice properly, so that effective treatment can be initiated Functional hearing loss occurs not only in adults, but also in children This diagnosis should be considered whenever hearing problems arise in musicians under great pressure regardless of age, including young prodigies Central Hearing Loss (Central Dysacusis) In central hearing loss, the damage is situated in the central nervous system at some point in the brain between the auditory nuclei (in the medulla oblongata) and the cortex Formerly, central hearing loss was described as a type of “perceptive deafness,” a term now obsolete Although information and research about central hearing loss has developed, it remains complex and unclear Physicians know that some patients cannot interpret or understand what is being said and that the cause of the difficulty is not in the peripheral mechanism but somewhere in the central nervous system In central hearing loss, the problem is not a lowered pure-tone threshold but the patient’s ability to interpret what he or she hears Obviously, it is a more complex task to interpret speech than to respond to a pure-tone threshold; consequently, the tests necessary to diagnose central hearing impairment must be designed to assess a patient’s ability to handle complex information Psychological Consequences of Hearing Loss Performing artists are frequently sensitive, somewhat “high-strung” people who depend on physical perfection in order to practice their crafts and earn their livelihoods Any physical impairment that threatens their ability to continue as musicians may be greeted with dread, denial, panic, depression, or similar responses, which may be perceived as exaggerated, especially by physicians who not specialize in caring for performers In the case of hearing loss, such reactions are common even in the general public Consequently, it is not surprising that psychological concomitants of hearing loss in musicians are seen in nearly all cases Many successful performers are communicative and gregarious and anything that impairs their ability to interact in their usual manner can be problematic Their vocational hearing demands are much greater than those required in most professions, and often musicians’ normal reactions to hearing loss are amplified by legitimate fears about interruption of their artistic and professional futures The problems involved in accurately assessing the disability associated with such impairments are addressed below in the discussion of occupational hearing loss in musicians Occupational Hearing Loss Performing artists are required to accurately match frequencies over a broad range, including frequencies above those required for speech comprehension Even mild pitch distortion (diplacusis) may make it difficult or impossible for musicians to play or sing in tune Elevated high-frequency thresholds may lead to excessively loud playing at higher pitches and to an artistically unacceptable performance, which may end the career of a violinist or conductor, for example It is extremely important for singers and other musicians to be protected from hearing loss However, the musical performance environment poses not only critical hearing demands, but also noise hazards Review of the literature reveals convincing evidence that music-induced hearing loss occurs, but there is a clear need for ongoing research to clarify incidence, predisposing factors, and methods of prevention It is interesting to note that, in direct contrast to many other publications, Johnson and Sherman evaluated 60 orchestra members and 30 nonmusicians from 250 to 20 000 Hz and found no substantive differences.4 This study suggested that there is no additional risk to hearing as a result of exposure to orchestral music Similarly, Schmidt and colleagues showed that the students of Rotterdam Conservatory did not show any decreased hearing loss when compared to a group of medical students of the same age, despite the music students’ exposure to music.5 As mentioned previously, noise exposure can cause both temporary and/or permanent hearing loss In a study to evaluate temporary threshold shift in performers and listeners, Axelsson and Lindgren determined that the performers showed less of a shift than the audience did.6 It was surmised by the authors that this may be explained by pre-exposure hearing levels The performers had poorer hearing levels than listeners did before being exposed to the study noise Another interesting finding was that the male listeners showed more of a temporary shift than the females The authors suggested that exposure to live pop music should be limited to 100 dBA or less for no more than hours When symphony orchestra musicians from the Royal Danish Theater were studied, Ostri et al found that 58% of the 95 subjects demonstrated a hearing loss when using 20 dB HL 15.  Hearing Loss in Singers and Other Musicians as the “normal” cutoff value The male subjects were more affected by noise exposure than the female subjects.7 The authors concluded that symphonic music does indeed cause hearing loss In 2014, Schmidt et al8 studied the hearing levels of 182 professional symphony orchestra musicians with varying degrees of exposure time and intensity For most of the musicians tested, the level of hearing loss was less than expected based on the 1999 International Organization for Standardization’s measure for predicting permanent threshold shifts based on duration and intensity of noise exposure.9 Although the level of hearing loss was generally less than predicted, they found that the ears with the highest exposure (above 90.4 dBA and a mean exposure time of 41.7 years) had an additional threshold shift of 6.3 dB compared to musicians with the lowest exposure In 1992, McBride et al set out to determine whether noise exposure affected the classical musician.10 Contrary to other studies, audiograms showed no significant differences between participants of the same sex and age They did prove that the musicians were exposed to high doses of noise, which pose an occupational hazard Drake-Lee studied heavy-metal musicians before and after performance.11 It was determined that exposure does cause a temporary threshold shift with a maximum effect at lower frequencies An article by Bu in 1992, examined hearing loss in Chinese opera orchestra musicians.12 Bu discovered that the incidence of hearing loss in this group was exceedingly high and apparently associated with the types of instruments used.12 Bu has suggested measures to combat the noise exposure other than the use of ear protectors, such as percussion musicians seated meter lower than the other musicians in order to better preserve hearing of the instrumentalists around them.12 However, such suggestions have a variety of drawbacks and practical limitations Occupational hearing loss is usually bilateral, fairly symmetrical, sensorineural hearing impairment caused by exposure to high-intensity workplace noise or music This subject has been discussed in this text, and specifically with regard to musicians in a previous review, in general in detail elsewhere.13 Music is one of the professions that can produce a somewhat asymmetrical hearing loss in selected cases It has been well established that selected symphony orchestra instruments, popular orchestras, rock bands, and personal stereo headphones produce sound pressure levels (SPL) intense enough to cause both temporary and permanent hearing loss Such hearing loss may also be accompanied by tinnitus and may be severe enough to interfere with performance, especially in violinists The vio- 263 lin is the highest-pitched string instrument in routine use The amount of hearing loss is related to the intensity of the noise, duration and intermittency of exposure, total exposure time over months and years, and other factors Rosanowski and Eysholdt published a case study on a violinist with bilateral tinnitus.14 They recorded peak sound pressure levels of over 90 dB The violinist showed a 20-dB drop in hearing between and kHz on the side with which the violin rests (left) This phenomenon (asymmetry) is produced by the head shadow, the same mechanism that causes asymmetrical hearing loss in rifle shooters The authors point out the potential hazard of other auditory symptoms (ie, tinnitus) as a result of noise exposure In their 1999 study of hearing, tinnitus, and exposure to amplified recreational noise, Metternich and Brusis found a very high risk of tinnitus even when subjects were exposed to short durations of amplified music.15 This risk appears to be greater than the risk of permanent hearing loss from the same exposure Various methods have been devised to help protect the hearing of performers For example, many singers and other musicians (especially in rock bands) wear ear protectors They may not feel comfortable wearing ear protection during a performance but may take precautionary measures during practice Ear protectors have changed tremendously over the years, and there are more sophisticated and suitable models available now that cater to the musician The importance of using new, more appropriate ear protectors for professional musicians should be stressed, especially because the previously unappreciated relationship between orchestral music exposure and noise-induced hearing loss has become clear In their 1983 publication, “The Hearing of Symphony Orchestra Musicians,” Karlsson et al determined that the criteria used to evaluate noise exposure in industry must be different from the criteria used to assess acoustic instrument levels in symphonic music.16 This complex issue is discussed later in this chapter Singers need to be made more aware of the hazards of noise exposure and find ways to avoid or reduce its effects whenever possible They should also be careful to avoid exposure to potentially damaging avocational noise such as loud music through headphones, chainsaws, snowmobiles, gunfire, motorcycles, and power tools Hoppmann has reviewed the hazards of being an instrumental musician, including hearing loss, and he emphasizes the need for a team approach to comprehensive arts-medicine diagnosis and care.17 Noise exposure has a cumulative effect, and exposure to these other types of noise just compounds the damage to a performer In his article 264 Clinical Assessment of Voice entitled, “Binaural hearing in music performance,” Donald Woolford evaluated the effects of hearing impairment on performance and found no direct correlation between degree of hearing impairment and level of performance.18 Clinical observations in the authors’ practice suggest that the rock performance environment may be another source of asymmetrical noise-induced hearing loss, a relatively unusual situation because most occupational hearing loss is symmetrical Rock singers and instrumentalists tend to have slightly greater hearing loss in the ear adjacent to the drum and cymbal, or the side immediately next to a speaker, if it is placed slightly behind the musician Various methods have been devised to help protect the hearing of rock musicians For example, most of them stand beside or behind their speakers, rather than in front of them In this way, they are not subjected to peak intensities, as are the patrons in the first rows The problem of occupational hearing loss among classical singers and other musicians is less obvious but equally important In fact, in the United States, it has become a matter of great concern and negotiation among unions and management Various reports have found an increased incidence of high-frequency sensorineural hearing loss among professional orchestra musicians as compared to the general public, and sound levels within orchestras have been measured between 83 and 112 dBA, as discussed below The size of the orchestra and the rehearsal hall are important factors, as is the position of the individual instrumentalist within the orchestra Players seated immediately in front of the brass section appear to have particular problems, for example Individual classical instruments may produce more noise exposure for their players than assumed In their study entitled “Hearing assessment of orchestral musicians,” Kahari et al reported that male musicians have a more pronounced highfrequency hearing loss than females exposed to the same musical noise.19 They also noted that percussion and woodwind players demonstrated a slightly more pronounced hearing loss than musicians of large string instruments Because many singers and instrumentalists practice or perform to hours a day (sometimes more), such exposure levels may be significant An interesting review of the literature may be found in the report of a clinical research project on hearing in classical musicians by Axelsson and Lindgren.20 They also found asymmetrical hearing loss in classical musicians, greater in the left ear This is a common finding, especially among violinists A brief summary of most of the published works on hearing loss in musicians is presented below In the United States, various attempts have been made to solve some of the problems of the orchestra musician, including placement of Plexiglas barriers in front of some of the louder brass instruments; alteration in the orchestra formation, such as elevation of sections or rotational seating; changes in spacing and height between players; use of specialized musicians, ear protectors; and other measures These solutions have not been proven effective, and some of them appear impractical, or damaging to the performance The effects of the acoustic environment (concert hall, auditorium, outdoor stage, etc) on the ability of music to damage hearing have not been studied systematically Recently, popular musicians have begun to recognize the importance of this problem and to protect themselves and educate their fans Some performers are wearing ear protectors regularly in rehearsal and even during performance, as noted in the press in 1989.21 In a 5-year study of the health of 377 professional orchestra musicians, Ackermann et al reported that 64% of the musicians who responded to the survey used earplugs at least intermittently They also highlighted the need for hearing protection by reporting that “For average reported practice durations (2.1 hour per day, days a week), 53% would exceed accepted permissible daily noise exposure in solitary practice, in addition to sound exposure during orchestral rehearsals and performance.”22(p8) Considerable additional study is needed to provide proper answers and clinical guidance for this very important occupational problem In fact, a review of the literature on occupational hearing loss reveals that surprisingly little information is available on the entire subject Moreover, all of it is concerned with instrumentalists; few similar studies in singers were found In 2008, Hamdan et al recorded the transient-evoked otoacoustic emissions (TEOAEs) of 23 normal hearing singers and found them to be less robust than those of the control group These results suggest subtle cochlear dysfunction possibly resulting from increased noise exposure during practice and performance The authors propose using TEOAE measurement as a tool to identify ears as “at risk for music-induced hearing loss.”23 Study of the existing reports reveals a variety of approaches Unfortunately, neither the results nor the quality of the studies is consistent Nevertheless, familiarity with the research already performed provides useful insights into the problem In 1960, Arnold and Miskolczy-Fodor studied the hearing of 30 pianists SPL measurements showed that average levels 15.  Hearing Loss in Singers and Other Musicians were approximately 85 dB SPL, although periods of 92 to 96 dB SPL were recorded.24 The A-weighting network was not used for sound level measurements in this study No noise-induced hearing loss was identified The pianists in this study were 60 to 80 years of age; and, in fact, their hearing was better than normal for their age Flach and Aschoff,25 and later Flach,26 found sensorineural hearing loss in 16% of 506 music students and professional musicians, a higher percentage than could be accounted for by age alone, although none of the cases of hearing loss occurred in students Hearing loss was most common in musicians playing string instruments Flach and Aschoff also noticed asymmetrical sensorineural hearing loss worse on the left in 10 of 11 cases of bilateral sensorineural hearing loss in instrumentalists.25 In one case (a flautist), the hearing was worse on the right In 4% of the professional musicians tested, hearing loss was felt to be causally related to musical noise exposure Histories and physical examinations were performed on the musicians, and tests were performed in a controlled environment This study also included interesting measurements of sound levels in a professional orchestra Unfortunately, they are reported in DIN-PHONS, rather than dBA In 1968, Berghoff 27 reported on the hearing of 35 big band musicians and 30 broadcasting (studio) musicians Most had performed for 15 to 25 years, although the string players were older as a group and had performed for as many as 35 years In general, they played approximately hours per day Hearing loss was found in 40- to 60-year-old musicians at 8000 and 10 000 Hz Eight musicians had substantial hearing loss, especially at 4000 Hz Five out of 64 (8%) cases were felt to be causally related to noise exposure No difference was found between left and right ears, but hearing loss was most common in musicians who were sitting immediately beside drums, trumpets, or bassoons Sound level measurements for wind instruments revealed that intensities were greater meter away from the instrument than they were at the ear canal Unfortunately, sound levels were measured in PHONS Lebo and Oliphant studied the sound levels of a symphony orchestra and two rock-and-roll orchestras.28 They reported that sound energy for symphony orchestras is fairly evenly distributed from 500 to 4000 Hz, but most of the energy in rock-and-roll music was found between 250 and 500 Hz The SPL for the symphony orchestra during loud passages was approximately 90 dBA For rock-and-roll bands, it reached levels in excess of 110 dBA Most of the time, during rock music performance, sound energy was louder than 265 95 dBA in the lower frequencies; symphony orchestras rarely achieved such levels However, Lebo and Oliphant made their measurements from the auditorium, rather than in immediate proximity to the performers.28 Consequently, their measurements are more indicative of distant audience noise exposure than that of the musicians or audience members in the first row In 2008, O’Brien, Wilson, and Bradley29 studied orchestral SPLs They found the musicians at the greatest risk of sustained noise exposure to be the principal trumpeter, first and third hornists, and principal trombonist They also noted the highest peak SPLs in the percussion and timpani sections Rintelmann and Borus studied noise-induced hearing loss in rock-and-roll musicians, measuring SPL at various distances from to 60 ft from center stage.30 They studied different rock-and-roll groups in locations and measured a mean SPL of 105 dB Their analysis revealed that the acoustic spectrum was fairly flat in the low- and mid-frequency region and showed gradual reduction above 2000 Hz They also detected hearing loss in only 5% of the 42 high school and college student rock-and-roll musicians they studied The authors estimated that their experimental group had been exposed to approximately 105 dB (SPL) for an average of 11.4 hours a week for 2.9 years In 1970, Jerger and Jerger studied temporary threshold shifts (TTSs) in rock-and-roll musicians.31 They identified TTSs greater than 15 dB in at least one frequency between 2000 and 8000 Hz in of musicians studied prior to performance and within hour after the performance Speaks and coworkers32 examined 25 rock musicians for threshold shifts, obtaining measures between 20 and 40 minutes following performance In this study, shifts of only to dB at 4000 and 6000 Hz were identified TTSs occurred in about half of the musicians studied Six of the 25 musicians had permanent threshold shifts Noise measurements were also made in 10 rock bands Speaks et al found noise levels from 90 to 110 dBA Most sessions were less than hours, and actual music time was generally 120 to 150 minutes The investigators recognized the hazard to hearing posed by this noise exposure In 1972, Rintelmann, Lindberg, and Smitley studied the effects of rock-and-roll music on humans under laboratory conditions.33 They exposed normal hearing females to rock-and-roll music at 110 dB SPL in a sound field They also compared subjects exposed to music played continuously for 60 minutes with others in which the same music was interrupted by minute of ambient noise between each 3-minute musical selection At 4000 Hz, they detected mean TTSs of 266 Clinical Assessment of Voice 26 dB in the subjects exposed to continuous noise, and 22.5 dB in those exposed intermittently Both groups required approximately the same amount of time for recovery TTSs sufficient to be considered potentially hazardous for hearing occurred in slightly over 50% of the subjects exposed to intermittent noise and in 80% of subjects subjected to continuous noise A study by Samelli et al34 in 2012, compared different areas of the auditory pathway of professional pop/rock musicians with that of nonmusicians The participants included 16 young male pop/rock musicians who had been performing for at least years, and a group of age-matched peers Although the researchers found damage to the peripheral auditory system evidenced by higher pure-tone thresholds and smaller TEOAE amplitudes, they found no damage to the central auditory nervous system The researchers assessed the central auditory system using auditory brainstem response (ABR) testing Both groups were within the normal range However, the group of pop/ rock musicians had earlier neural responses to the acoustic stimuli, suggesting better or faster processing of acoustic information Samelli et al attribute this to musical training providing improved processing of acoustic information and improved spontaneous attention to sound While their speculation might be correct, the findings also could be explained by mild hyperacusis associated with noise-induced sensorineural impairment Alternatively, it might be that their superior hearing performance was present from birth and predisposed them to choose careers as musicians The findings also could be irrelevant clinically In 1972, Jahto and Hellmann35 studied 63 orchestra musicians playing in contemporary dance bands Approximately one-third of their subjects had measurable hearing loss, and 13% had bilateral highfrequency loss suggestive of noise-induced hearing damage They also measured peak SPL of 110 dB (the A scale was not used) They detected potentially damaging levels produced by trumpets, bassoons, saxophones, and percussion instruments In contrast, in 1974, Buhlert and Kuhl36 found no noise-induced hearing loss among 17 performers in a radio broadcasting orchestra The musicians had played for an average of 20 years and were an average of 30 years of age In a later study, Kuhl37 studied members of a radio broadcasting dance orchestra over a period of 12 days The average noise exposure was 82 dBA He concluded that such symphony orchestras were exposed to safe noise levels, in disagreement with Jahto and Hellmann.35 Zeleny et al studied members of a large string orchestra with intensities reaching 104 to 112 dB SPL.38 Hearing loss greater than 20 dB in at least one frequency occurred in 85 of 118 subjects (72%), usually in the higher frequencies Speech frequencies were affected in people (5%) Conversely, in 2007, Reuter and Hameroshoi39 found no evidence of TTSs or changes in otoacoustic emissions for 12 normal hearing symphony orchestra musicians, both before and after rehearsals In 1976, Siroky et al reported noise levels within a symphony orchestra ranging between 87 and 98 dBA, with a mean value of 92 dBA.40 Audiometric evaluation of 76 members of the orchestra revealed 16 musicians with hearing loss, 13 of them sensorineural Hearing loss was found in 7.3% of string players, 20% of wind players, and 28% of brass players All percussionists had some degree of hearing loss Hearing loss was not found in players who had performed for fewer than 10 years but was present in 42% of players who had performed for more than 20 years This study needs to be reevaluated in consideration of age-matched controls At least some of the individuals reported have hearing loss not causally related to noise (eg, those with hearing levels of 100 dB HL in the higher frequencies) In a companion report, Folprechtova and Miksovska also found mean sound levels of 92 dBA in a symphony orchestra with a range of 87 to 98 dBA.41 They reported that most of the musicians performed between and hours daily They reported the sound levels of various instruments as seen in Table 15–1 A study by Balazs and Gotze, also in 1976, agreed that classical musicians are exposed to potentially damaging noise levels.42 The findings of Gryczynska and Czyzewski supported the concerns raised by other authors.43 In 1977, they found bilateral normal Table 15–1.  Sound Levels of Various Instruments Instrument Sound Level (dBA) Violin 84–103 Cello 84–92 Bass 75–83 Piccolo 95–112 Flute 85–111 Clarinet 92–103 French horn 90–106 Oboe 80–94 Trombone 85–114 Xylophone 90–92 Source:  Data from Folprechtova and Miksovska.41 ... Hearing 20 08 ;29 (3):360–377 24 Arnold GE, Miskolczy-Fodor F Pure-tone thresholds of professional pianists Arch Otolaryngol 1960;71:938–947 27 2 Clinical Assessment of Voice 25 Flach M, Aschoff E [On... 1981;(377):3–74 28 Lebo CP, Oliphant KP Music as a source of acoustic trauma Laryngoscope 1968; 72( 2): 121 1– 121 8 29 O’Brien I, Wilson W, Bradley A Nature of orchestral noise J Acoustic Soc Am 20 08; 124 (2) : 926 –939.. .25 8 Clinical Assessment of Voice Figure 15–1.  Cross section of the ear The semicircular canals are part of the balance system as part of the body’s balance mechanism, and (2) the cochlea,
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Xem thêm: Ebook Clinical assessment of voice (2E): Part 2, Ebook Clinical assessment of voice (2E): Part 2, Appendix IB. Patient History: Professional Voice Users, Appendix IIIC. Objective Voice Analysis and Laryngeal Electromyography, Appendix IIIF. Acting Voice Specialist’s Report

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