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|Year : 2003 | Volume
| Issue : 18 | Page : 25--30
Does health promotion work in relation to noise?
Rikshospitalet University Clinic, Oslo, Norway
H M Borchgrevink
Executive Director, Medicine & Health, The Research Council of Norway (RCN) Boks 2700 St.-Hanshaugen, N-0131 Oslo
Noise is a health risk. The only scientifically established adverse health effect of noise is noiseinduced hearing loss (NIHL). Besides noise may affect quality of life and cause annoyance and sleep disturbance. The present scientific evidence of potential non-auditory effects of noise on health is quite weak.
Whether health promotion works in relation to noise may be reflected by permanent hearing threshold shift development in population studies. Hearing impairment continues to be the most prevalent disability in Western societies. The National Institute of Occupational Safety and Health (NIOSH) still rates noise induced hearing loss among the top ten work-related problems. Recent studies report that employees continue to develop noise induced hearing loss although to a lesser extent than before, in spite of occupational hearing conservation programmes. Besides socio-acusis and leisure noise seem to be an increasing hazard to hearing, also in young children and adolescents. This seems partly related to acute leisure noise exposure (e.g. toy pistols, amplified music). However, population studies increasingly find nonnormal high-frequency hearing including the characteristic NIHL-«DQ»notch«DQ» around 6kHz also in subjects who do not report noise exposure incidents or activities. Today 12.5% of US children 6-19 years show a noise-«DQ»notch«DQ» in one or both ears (n= 5249, Niskar et al 2001). A Norwegian county audiometry survey on adults > 20 years (n=51.975) showed mean unscreened thresholds +10dB at 6kHz for both genders even for the youngest age group 20-24 years (Borchgrevink et al 2001). Accordingly, the present health promotion initiatives seem insufficient in relation to noise and noise-induced hearing loss.
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Borchgrevink H M. Does health promotion work in relation to noise?.Noise Health 2003;5:25-30
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Borchgrevink H M. Does health promotion work in relation to noise?. Noise Health [serial online] 2003 [cited 2020 Jul 12 ];5:25-30
Available from: http://www.noiseandhealth.org/text.asp?2003/5/18/25/31821
The present scientific evidence of potential nonauditory effects of noise on health is quite weak - too weak to influence standards and regulations (Porter et al., 1998). Noise may affect quality of life and cause annoyance and sleep disturbance. The only scientifically established adverse health effect of noise is noise-induced hearing loss (NIHL). An evaluation of whether health promotion works in relation to noise should accordingly be based on an adequate outcome parameter for NIHL, i.e. permanent hearing threshold shift development reflected in population studies. Hearing impairment continues to be the most prevalent disability in Western societies (Davis, 1997; Wilson et al., 1999). It is estimated that 11% of the total population in the US and Europe are at risk for hearing loss from noise (Alberti, 1998).
The National Institute of Occupational Safety and Health (NIOSH), USA, still rates noise induced hearing loss among the top ten workrelated problems, involving at least 11 million workers in the US (Ishii and Talbott, 1998). Recent studies report that employees continue to develop noise induced hearing loss in spite of hearing conservation programmes. In the military, Swiss conscripts showed significant changes in otoacoustic emissions (TEOAE) at 2kHz and 4kHz after 17 weeks training (Hotz et al., 1993). German recruits showed permanent NIHL >25 dB for a percentage of the group after 2 months training (Joachims et al., 1993). Finnish conscripts demonstrated a deterioration of 5 dB median hearing loss 2-8 kHz (Kiukaanniemi et al., 1992). In UK, NIHL is still the single largest category of disability seen after military service with a 28 % prevalence of acoustic trauma in the British Army, despite the Hearing Conservation Programme initiated in 1965 (Bennett and Kersebaum, 1996). Occupational NIHL remains epidemic in the US Air Force aircrew members and radio operators (Ritter and Perkins, 2001). In the US, Navy and Marine Corps men still have worse hearing threshold levels than Occupational Safety and Health Administration age-corrected values throughout most of their careers (Bohnker et al. 2002a). Compared with historical data significant threshold shifts were though lower for the most junior enlisted personnel, indicating improved protection in later years (Bohnker et al., 2002b).
Leisure noise and socio-acusis
Socio-acusis and leisure noise seem to be an increasing hazard to hearing, also in young children and adolescents. This seems partly related to acute leisure noise exposure (e.g. toy pistols, amplified music). Noise typically leads to high-frequency hearing loss with largest threshold shifts, a "notch" around 3-6 kHz. Popmusic tends to give the largest threshold shift at 6 kHz (Passchier-Vermeer et al., 1998).
Estimates of risk of NIHL from amplified music claim that around 10% of young people are expected to suffer a 10 dB NIHL at 3 kHz in both ear after 10 years of amplified music exposure (Hoffmann, 1997). The high-frequency hearing loss from music listening through headphones has been estimated to 20 dB in 5% of teenagers after 5 years (Ising et al., 1994). A Dutch study which found listening levels under headphones to be 10-15 dB lower in 1997 than estimated in 1989, concluded that pop-music had caused a 3 dB average loss at 4 and 6 kHz in 6.5% of young persons - which corresponds to the age-related threshold shift recorded from 20 to 30 years (Passchier-Vermeer et al., 1998).
Music listening by headphones may lead to temporary threshold shifts (TTS) (e.g. TurunenRise et al., 1991; Hellstrom et al., 1998) and permanent threshold shift (PTS) (e.g., Fearn and Hanson, 1984; Katz et al., 1982; Mori, 1985; Meyer-Bisch, 1996; Mercier et al., 1998). Other studies claim no influence on PTS (Wong et al., 1990; Hellstrom, 1991; Mostafapour et al., 1998) (studies that emphasise mean high-frequency shifts rather than "notches" will implicitly conceal NIHL effects and favour age effects in their interpretation of data). TTS is also reported after music exposure in aerobic class (Nassar, 2001). Tinnitus, a symptom of both temporary and permanent noise-induced threshold shift, has been reported in up to 2/3 of discotheque visitors (Meyer-Bisch, 1996; Mercier et al., 1998, Maassen et al, 2001), the prevalence being higher for those attending the noisier discotheques (Tin and Lim, 2000). Repeated TTS is regarded to lead to a corresponding PTS (NATO, 1986). US-NCHS indicated effects of music-induced hearing loss beginning in the late 1960s (Jekel, 1996). High-frequency hearing loss is still significantly associated with noisy leisure activities in general (Dalton et al., 2001), e.g. recreational firearm use (Nondahl et al., 2000; Stewart et al., 2001). Acute acoustic trauma may be seen in young people even after short term or incidental noise exposure, e.g. toy pistol firing (Fleischer et al., 1999) and loud amplified music (Metternich and Brusis, 1999).
Non-normal high-frequency permanent threshold shifts have been recorded in children at start of school (Kruppa et al., 1995), in adolescents in Austria (Korpert, 1992), Germany (Becher et al., 1996; Struwe et al., 1996; Ising and Babisch, 1998), France (Meyer-Bisch, 1996; Mercier et al., 1998), Japan (Inoue et al., 1996) and the Netherlands (Passchier-Vermeer et al., 1998); in studies on young adults 15-45 years in Australia (Murray & LePage, 1993), and in conscripts at entry in Sweden (Rosenhall et al., 1993), Norway: increasing in the 1980's, declining in the 1990's (Borchgrevink, 1988; 1993), Canada (Pelausa et al., 1995), Germany (Hoffmann, 1997) and Italy (Merluzzi et al., 1997).
In audiometric surveys from various countries the median hearing threshold levels of any group of 18-20 year olds, are not zero dB, but on the order of + 5 dB for most frequencies 0.25-8 kHz and with higher values (e.g., 13.5 dB) for 6 kHz (extensively discussed by Ward, 1990; 1993). In UK, adults 18-30 years show 4.3 dB poorer thresholds than "audiometric zero" (ISO 389, 1994) for the average of 0.5, 1,2, and 4 kHz with even greater shifts for 0.25, 6 and 8 kHz (Lutman and Davis 1994). Recent studies showing a 6 kHz noise "notch" include 22+28% of college student volunteers (Mostafapour et al., 1998) and in median thresholds of classical orchestral musicians, males (a) and females (b) (Kahari et al., 2001 a+b). In electrical transmission workers the 4 kHz shift registered in 4% correlated with reported noise exposure (questionnaire) while the 6 kHz shift in 31% did not (McBride and Williams, 2001).
Even large population studies increasingly find non-normal high-frequency hearing including the characteristic NIHL-"notch" around 6kHz, also in subjects who do not report noise exposure incidents or activities. Today 12.5% of US children 6-19 years show a noise-"notch" in one or both ears (n=5249, Niskar et al., 2001). A Norwegian county audiometry survey on adults > 20 years (n=51.975) showed mean unscreened thresholds +10dB at 6kHz for both genders even for the youngest age group 20-24 years. The elevated prevalence for > 25 dB loss at 6 kHz in the better ear, present for both genders but most expressed for the younger males (Borchgrevink et al., 2001), is in line with the corresponding threshold elevation found for Australian young adults 15-45 years (Murray and LePage, 1993) and can not be explained by calibration error (see below). It agrees with the various reports on high-frequency threshold elevation in young adults (predominantly males) and is indicative of slight noise-related socio-acusis, most likely partly due to music noise.
If the recorded high-frequency thresholds shifts do not reflect true hearing loss, the "audiometric zero" (normal threshold for young adults) must be too restrictive. Parts of the threshold elevation might possibly be due to calibration error related to the introduction of the ISO 389 (1994) standard, which includes use of artificial ear (Smith and Lutman, 1992). The 6 kHz "notch" has been claimed to be related to directional phenomena of sound from the headset in the ear canal. If so, one must explain why this did not influence the previous population studies underlying the 6 kHz "audiometric zero" (ISO 389, 1994), and how it can be so prevalent across studies in children and adults using headsets from different manufacturers.
From the above it seems reasonable to conclude that the high-frequency hearing threshold shifts, including the 6 kHz "notch", being recorded in large fractions of subjects in a number of studies including large population surveys, reflect a true noise induced hearing deterioration affecting a large fraction of the population. As these threshold shifts are seen even in young subjects unexposed to occupational noise, people are at risk for noise-induced hearing loss due to socioacusis - the general noise exposure experienced as a Western citizen - including leisure noise, e.g. weapon noise and amplified music. Populations at risk should be monitored by sensitive methods, e.g. otoacoustic emission (OAE), by conventional TEOAE, or using maximum length sequences TEOAE-MLS (Hall and Lutman, 1999) or distortion products DPOAE (Marshall et al., 2001). Aged subjects seem more susceptible due to impaired spontaneuos repair mechanisms (Miller et al., 1998), especially those with a prior NIHL history (Gates et al., 2000; 2001). Age and noise effects do not seem to be simply additive and individual susceptibility differences are substantial (Mills et al., 1998; 2001). Race and ethnicity, and possibly socioeconomy, also seem to influence susceptibility (Rosen et al., 1964; Clark and Bohl, 1996; Lee et al., 1996; Ishii and Talbott, 1998).
Accordingly, at present health promotion initiatives seem insufficient regarding prevention of noise-induced hearing loss.
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