There have been several recent reports on the potential risk to hearing from various types of social noise exposure. However, there are few population-based data to substantiate a case for concern. During the last 10-20 years use of personal cassette players (PCPs) has become very much more prevalent, and sound levels in public nightclubs and discotheques are reported to have increased. This study investigated the prevalence and types of significant social noise exposure in a representative population sample of 356 18-25 year olds in Nottingham. Subjects were interviewed in detail about all types of lifetime noise exposure. Noise measurements were also made for both nightclubs and PCPs. In the present sample, 18.8% of young adults had been exposed to significant noise from social activities, compared with 3.5% from occupational noise and 2.9% from gunfire noise. This indicates that social noise exposure has tripled since the early 1980s in the UK. Most of the present day exposure, measured in terms of sound energy, comes from nightclubs rather than PCPs. Moreover, 66% of subjects attending nightclubs or rock concerts reported temporary effects on their hearing or tinnitus. As will be reported in a later publication, any persistent effect of significant noise exposure on 18-25 year olds is difficult to show, however these data suggest that further work is indicated to study the possibility of sub-clinical damage, and also to consider the implications for employees of nightclubs.
Keywords: prevalence, noise immission, social noise, young adults.
|How to cite this article:|
Smith PA, Davis A, Ferguson M, Lutman ME. The prevalence and type of social noise exposure in young adults in England. Noise Health 2000;2:41-56
| Introduction|| |
Hearing threshold levels in the population of the United Kingdom have been characterised by the UK National Study of Hearing (NSH) carried out by the MRC Institute of Hearing Research. From data obtained in the NSH, Lutman and Davis (1994) showed that hearing in otologically normal young adults was not as acute as is defined by the internationally standardised norm for audiometric zero (ISO 389, 1991). They reported that median pure tone air conduction thresholds were nearer 5 dB than zero across the frequency range 0.5 to 4 kHz, and even more discrepant outside this frequency range. This discrepancy has been echoed in other studies conducted in the past two decades (eg Robinson et al, 1981; Buren et al, 1992). It may be due to problems with the standard itself, (see Smith et al 1998). There may also be an influence of the rather noisier environment and lifestyle of the 1990s, causing hearing in young adults today to be less acute than in earlier years.
In 1984 the MRC Institute of Hearing Research published a review of the current literature on social noise and concluded that previous research was sparse and had often used inappropriate methodology. However there was little evidence that social noise constituted a public health problem: although the sound pressure levels may be as high as in industry, the pattern of exposure probably shows less frequent exposure and for a relatively short overall fraction of lifetime. A random sample population study of social noise exposure was recommended, to ascertain not only numbers exposed, but also exposure levels and patterns of exposure.
Since that review in 1984, personal cassette players (PCPs) have become very popular, and media reports suggest public concern over their use especially at high levels. There have been several studies that have provided some data on the PCP listening habits of young people.
[Table - 1] summarises the findings from a number of studies.
Bradley et al (1987) reported from data gathered by questionnaire that 37% of her sample of 11-18 year olds owned a PCP and 61% of the sample reported attending discotheques. About half those attending discotheques reported temporary symptoms after exposure, compared with only about 10% of PCPs owners. This would suggest that young people are quite moderate in their use of PCPs and are less likely to elicit temporary effects than might have been supposed. Bradley et al also measured enjoyable listening levels in quiet. In 11 PCP users, the mean was 84 dB(A) as measured by the KEMAR manikin (Knowles Electronics Manikin for Acoustic Research). This is equivalent to a free field level of 74 dB(A), (see Rice et al, 1987a, for details on converting KEMAR measurements to free field equivalent levels). Males were found to set higher levels than females.
Rice et al (1987a) reported on a laboratory study of 20 regular PCP users and also a further sample of 41 PCP users whom they stopped in the street to measure their actual listening level. They found no significant correlation between listening level and background noise level, or hours of use. They estimated the number of individuals at risk from PCP noise exposure to be 5%, as this is the number estimated to be exposed to >90 dB(A) as a daily dose. This assessment assumes music to damage hearing in the same way as occupational noise, and also assumes that PCP habits continue for a long time. Rice et al (1987b) carried out a further study in which 13-19 year old subjects reported mainly home use of a PCP and 26% reported temporary effects after use. They then pooled these data with other studies in Nottingham and London (Bradley et al, 1987; Mark, 1985) and with their own (Rice et al, 1987a) to show that males use PCPs more hours per week than females. There was no correlation between age and hours of use in the pooled sample, which was primarily aged below 25 years.
Hellstrom and Axelsson (1988) investigated a sample of 154 14-15 years old and estimated that more than 5% used PCPs for more than 7 h/week. They also investigated temporary effects and found that 10% reported tinnitus, compared with 64% who reported tinnitus following high sound levels at pop concerts, and 5% who reported tinnitus following hi-fi use. Hellstrom (1991) showed in a group of 468 16 year olds (the respondents from a random sample of 500 males and 500 females) that there was no significant correlation between use of PCPs and hearing, as measured by pure tone audiometry. This finding contradicts other studies of hearing in young adults, that have assumed that any hearing loss they found was resulting from social noise exposure (e.g. Axelsson et al, 1987; Borchgrevink, 1988). The lack of effects on hearing is supported by Lindeman (1987) who reported no deterioration in hearing in a group of 17-23 year old males studied over a three-year period.
Turunen-Rise et al (1991a, 1991b) concluded from their laboratory study that the risk to hearing from PCPs was minimal at typical user levels. Unlike Rice et al, they question the relevance of applying limits specified for occupational noise to music, due to greater variation in spectral content and level, and more pauses in the latter. There is some evidence (Lindgren and Axelsson, 1983; Swanson et al, 1987) to suggest that music is less harmful to hearing than noise of equivalent sound pressure levels, and there is also some evidence that spreading the energy over a longer time period causes less permanent damage to the auditory system (Hamernik and Ahroon, 1998).
Airo et al (1996) carried out both laboratory work and a field study, involving 45 subjects, aged 15 to 32 years. They used their own design of acoustic coupler to show that all 12 current PCPs that they tested were capable of producing damaging sound levels. Most users listened at low enough levels to avoid damage. Unlike Rice et al (1987a) they reported a significant regression coefficient between background noise and PCP listening level, in their group of mainly regular users, and they recommended that PCPs be avoided in noise >70 dB(A) free field equivalent.
Meyer-Bisch (1996) reported on questionnaire data on 1364 volunteer subjects from Nancy, France, on use of PCP, attendance at discotheques and rock concerts. Questions related to current attendance patterns. He then used fine frequency audiometry and did show significantly poorer hearing in those with high exposure from PCPs (more than 7 h/week) and rock concerts (more than once a month). No effect on hearing of attending discotheques (more than once a month), was seen although 16.9% reported this frequency of attendance. Males were found to listen for longer to PCPs than females. This study did not attempt measurement of sound levels, and the sample was self-selecting, and may have encouraged those with problems to attend.
Ising et al (1997) reported on PCP and discotheque levels and attendance in 569 schoolchildren aged 10-17 years old, from 6 schools in Germany. The aim of their study was to estimate risk of hearing damage. They found that within the age range 10-16 years, the median PCP listening levels increased with increasing age, from 78 to 97 dB(A) and then decreased in 17 year olds. Using ISO 1999 (1990), they predicted that listening to earphone music for 5 years would give rise to noise induced hearing loss of at least 10 dB at 3 kHz in 10% of pupils and concluded that urgent action is needed.
Jokitulppo et al (1997) reported on the potential weekly noise exposure in a sample of 405 Finnish 12-17 year olds, using a questionnaire. They estimated that 51% of their subjects reach a weekly dose of equivalent to at least 85 dB(A) for a 37-hour working week. Over 70% reported temporary tinnitus and 45% reported temporary hearing loss following noise exposure, and they too concluded that more information about leisure noise exposure is required.
It is apparent from the foregoing that there is a considerable literature on the potential risk to hearing from various types of social noise exposure. However, most studies used convenience samples that are susceptible to bias. The present analysis is based on a population based sample obtained for several purposes. The main aim of the study was to measure hearing in a large group of randomly sampled young adults aged between 18 and 25 years, and to compare the results with both ISO 389 (1991) and with Lutman and Davis (1994). Part of the study entailed detailed documentation of lifetime noise exposure as part of the implementation of criteria for otological normality. This report differs from previous work in that the noise history covered all aspects of noise exposure throughout the entire lifetime of each individual, rather than covering only current habits. The report focuses on the prevalence of significant noise exposure and details the patterns and types of noise exposure, in particular social noise exposure. A further analysis to be published, will address the question of the effects of social noise on hearing and on reported tinnitus. Because there is so much literature on PCP use, (rather than other types of social noise) with little population data, the present study was designed with particular attention to PCP use, at all sound levels and not only those considered to be potentially damaging.
| Methods|| |
A two stage sampling technique was used. In the first stage a postal questionnaire was sent to 5850 households in the Nottingham area which had been randomly selected from the postal address file. The mailing took place in the summer of 1994. The questionnaire concerned hearing, tinnitus, noise exposure, use of primary health care and hospital Ear, Nose and Throat services, as well as demographic characteristics. Questions were to be completed for each member of the household over the age of 14 years. All the 18 to 25 year old respondents were invited to attend a two-hour session in the clinic. Subjects were paid an attendance allowance and travelling expenses. Each subject was sent up to four invitations to attend. A total of 356 people attended.
A detailed history of lifetime noise exposure was taken which included occupational, gunfire and social situations. Details of all noisy situations were documented, where noisy was defined as any situation above which voices had to be raised for two people 4 feet apart with normal hearing to hold a conversation. If the noise allowed normal conversation under these circumstances, it was estimated to be 80 dB(A) or less and was not documented. For each different type of noise to which subjects had been exposed, the sound pressure level, the number of times they had been exposed and the duration of exposure were estimated. Also documented were any temporary effects that followed: dullness of hearing, tinnitus, or both, and in which ear. Details of any hearing protection and its usage were also recorded.
There were a number of different ways in which the sound pressure level of the noises could be estimated. In a very few cases, the individuals were aware of a measured level. For occupational noise, the audiologists had reference to a set of figures relating to the more prevalent local industries. For social noise levels, they had some data from the local Environmental Health Office. Sometimes, particularly for social noise, it was possible to use a Personal Cassette Player for the subject to set at approximately the level that they were trying to describe. On the majority of occasions however, a speech communication table was used, (Coles et al, 1987). This linked the level of voice (slightly raised, very loud, shout) required to hold a conversation above the noise at a distance of 4 feet, to a sound pressure level in dB(A), as shown in [Table - 2]. Inevitably, this estimation of sound pressure level was retrospective, and approximate. The Table was based on pilot work that had been carried out earlier at two local factories and the audiologists were very experienced in using the interview procedure.
Particular emphasis was placed on social noise exposure, including questions on the following situations: live rock concerts, nightclubs /discotheques, (separating out time spent in the bar from the dance floor which usually differed in sound pressure levels), PCPs in quiet and noisy situations, music through loudspeakers, parties, in-car music, television/computer games through earphones, motor cycle or other engine noise, "do-it-yourself" (D-I-Y) and any other noisy leisure pursuits. Extra care was taken to document use of PCPs, even if it was at a low intensity level (80 dB(A) or less). This part of the interview took up to about an hour in some cases where many different leisure pursuits at different sound levels were involved.
For each different activity leading to occupational or social noise exposure, having recorded the typical sound pressure level, and the total duration of the exposure, a number of exposure units was calculated, based on the equal energy principle. Within each category of occupational social and gunfire noise exposure, the units for each activity were summed and then converted into a single noise immission rating, or NIR. An NIR of 1 is the rating that was defined as significant: it is equivalent to a noise immission level (NIL) of 97 dB(A) or workday exposure of 80 dB(A) cumulated over 50 years. Further details of this noise energy estimation are given in the Appendix, [Table - 4],[Table - 5], and in Lutman and Spencer (1991).
Noise measurements in nightclubs /discotheques
In order to verify the estimates made of the sound pressure levels within nightclubs, measurements were made at 3 local nightclubs. This involved attending one nightclub on two occasions and the other two nightclubs on one occasion each, making repeated short term Aweighted Leq measurements throughout the evening at a number of different locations: the bar area, dancefloor and near to a speaker.
Socioeconomic status was based on occupation, dividing into manual or non-manual according to the Registrar General's classification (OPCS 1991). Because our sample included young adults, many of whom lived with their parents, this was done in two ways: firstly, we classified subjects according to the main occupation of the principal earner in the household. Secondly, we classified them according to the main occupation of their parents. Often these classifications were the same, but young adults living alone or with friends or spouses could be classified in two ways.
Listening level for Personal Cassette Player
Subjects were given a PCP (Panasonic Model RQ-P30) with a recording of Nirvana's "Unplugged In New York", and they were asked to play the first track ("About a girl"). This particular PCP was chosen as it had no adjustable graphic equalizer, and it had a volume wheel which was clearly marked from 1-10. The subjects were asked to set the volume to a level to which they would typically enjoy listening in a quiet room and this task was then repeated. There were two reasons for doing this: one was to assess the volume at which subjects used a PCP in a controlled situation, the other was to help us to estimate the level of other noise sources in the subjects history by using the PCP as a reference level. This particular recording was chosen because it was very popular amongst the age group. We also asked them questions on their use of PCP: age when they used it most frequently, whether they used one nowadays, and what sort of earphones they used: supra-aural or insert.
At approximately 4-week intervals throughout the phase of data collection, sound pressure level readings were taken of the music in dB(A). This was done by placing the earphones from the PCP onto the KEMAR manikin. It was for reasons of hygiene and ease of calibration that we chose to use supra-aural rather than insert earphones. The KEMAR readings were transformed into free field equivalents as described by Rice et al (1987a).
| Results|| |
The total number of questionnaires sent out to households was 5850. Responses were received from 3978 households, of which 3623 were completed questionnaires with entries from 6883 individuals over the age of 14 years. This gave a response rate of 70.4% for the first stage of the study. The age and sex distribution of the returned questionnaires did not differ significantly from the 1991 census for the postcodes sampled. All respondents aged between 18 and 25 years were invited to attend the clinic for the second stage of the study. A total of 356 accepted, representing 46.0% of those in the required age range at the outset of the study.
Results from all but 10 of the subjects were included in the analysis. Two had audiograms deemed unreliable at the time of test and 8 were just outside the required age range by the time they attended. There were 189 females and 157 males. The distribution of age was biased in favour of 18 year olds, because throughout the 2½ years of the data collection phase of the study more subjects were invited to attend as they became 18. There were no significant differences between the attenders and non-attenders in terms of postal responses to questions on hearing and noise exposure. However slightly more people attended who used a PCP nowadays and who reported after effects (chi-squared p<0.05). Also, there were significantly more people attending who reported an operation on either of their ears (chisquared p<0.05).
Prevalence and type of significant noise exposure
Overall, 23.1% of the group had been exposed to significant noise: 3.5% in their occupation, 2.9% by gunfire and 18.8% from social noise. [Figure - 1] compares these prevalences with those from the National Study of Hearing, (Davis 1995, n=231) which was conducted during the early 1980s using similar methods to assess noise exposure. The comparison indicates that social noise exposure has increased (from 6.7% to 18.8%) during that interval, whilst occupational noise has decreased (from 8.9% to 3.5%) and gunfire noise has remained fairly constant (3.1% to 2.9%) within this age group.
[Figure - 2] shows the percentage who had received significant noise exposure from various social activities. It is clear that nightclubs lead to the most noise immission with 11.3% of our population receiving significant noise exposure from them alone. Hi-fis and PCPs contribute much less exposure, affecting 3.2% and 2.0% respectively. Live concerts are generally louder than nightclubs but are not attended so often and lead usually to less overall noise immission.
There are a number of other less prevalent activities that give significant noise exposure including in-car music, motor sports and D-I-Y. Further inspection was made of the two variables that contribute to the calculation of noise immission level for nightclubs: estimated sound pressure level and exposure time for the 65 individuals who had accumulated significant social noise exposure. The mean attendance rate, in hours/year is approximately 222 hours (equivalent to 18.5 hours/month or 4.3 hours/week) or approximately one night a week. The range however is very wide: from 8 to 780 hours/year. The estimated sound pressure levels are also varied but there are more people at the higher end of the scale. The mean estimated sound pressure level is 101 dB(A). There is no significant correlation between hours/year and dB(A).
Males were found to have significantly more social noise exposure than females (chi-squared p<0.01) but no significant effect of parental or individual occupational group was found.
Temporary effects of social noise
[Figure - 3] shows the numbers of subjects who have ever participated in each of the four most popular noisy social activities, and also the numbers who reported temporary effects afterwards. Note that these people have not necessarily acquired significant noise exposure (as defined earlier) from each of these activities. Of those who attend nightclubs, 66.2% report temporary effects afterwards: dullness of hearing, tinnitus, or both. Of those attending rock concerts, 73.1% report these effects. By comparison, only 7.6% of hi-fi listeners and 16.9% of personal cassette player listeners reported these effects.
[Table - 3] shows the type and site of temporary effects reported. Tinnitus is more prevalent as an after-effect than dullness of hearing, although in many cases, both symptoms were reported. One individual reported permanent bilateral tinnitus, that started at a live rock concert.
Almost all these effects are bilateral. For example after nightclubs, only 3 people reported unilateral effects compared with 214 who reported bilateral effects.
There was no significant effect of age or sex on reports of temporary effects. Those in the group with significant social noise exposure reported significantly more temporary effects than those without (chi-squared p<0.01) after rock concerts and PCP used at 80 dB(A) or more.
Use of PCP
At interview, 43.6% of the sample admitted to use of a PCP nowadays, although there were only 15 individuals (less than 0.5%) who had never used one at all. There was a slightly higher percentage of people reporting use of insert rather than supra-aural earphones (58.0% compared with 42.0%). [Figure - 4] shows that the age at which subjects reported their most frequent use of a PCP was during their teenage years: 86.1% used a PCP most frequently between the ages 13 and 19 years, with a mean of 16.1 years.
[Figure - 5] shows the distribution of free field equivalent sound pressure levels that the subjects set in the quiet laboratory situation. These figures are the mean of two replications, the two data sets having a test-retest correlation coefficient of 0.95. The mean value is 74.0 dB, and only 6.9% of the sample chose a level of 90 dB(A) or above. (The maximum available setting was 96 dB(A).)
Males set PCP levels (mean 78.6 dB(A)) significantly higher than females (mean 71.1 dB(A)), (t=6.7, p=0.00) but no effect of occupational group was found. There was also a significant effect of social noise exposure (t=4.8, p=0.00), in that the group with significant social noise set a mean level of 80.3 dB(A) compared with 73.1 dB(A) for those with no significant social noise exposure.
Sound pressure levels in nightclubs
Sound levels were measured in three local nightclubs, each of which had been attended frequently by many of our subjects. A summary of the measurements is shown in [Figure - 6]. The range of levels measured is broad, varying between clubs, actual location within a club, the time in the evening and between different evenings in the same club. If a subject reported attending (for example) the first one of these nightclubs, it can only be inferred that they had been exposed to a level within the range 85 - 105 dB(A).
| Discussion|| |
Social noise exposure in 18-25 year olds in Nottingham in the mid 1990s was significantly more prevalent at 18.8% than it was in the early 1980s at 6.7%. The interviews on noise exposure were carried out using similar protocols but the minor differences between them are not enough to account for the change in prevalence.
Gunfire noise exposure has remained constant at 2.9%. This contrasts with reports from other countries. For example, in the USA recreational hunting or target shooting is considered the greatest threat to hearing of all social noise (Clarke, 1992) and in Finland school children were found to spend an average of 3.8 h/week shooting (Jokitulppo et al, 1997). All of the gunfire noise exposure in the present sample came from rifles, shotguns or machine guns. By comparison, the prevalence of material occupational noise exposure has decreased significantly, probably in part due to a decrease in the number of local coal mining and manufacturing jobs.
The increased noise immission is not primarily due to PCPs. This finding is in broad agreement with others (Rice et al, 1987; Turunen-Rise et al, 1991) and indicates that risks to hearing from PCPs are minimal in population terms. It is clear that PCP noise exposure is only hazardous if it continues for a long time. Most subjects in the present sample made maximum use of their PCPs as teenagers below the age of 18 years (in agreement with Ising, 1997) and despite this, only 2% of them have accumulated significant noise exposure from PCPs. Only 6.9% chose an enjoyable listening level of 90 dB(A) or more.
However those in noisy occupations or with significant social noise exposure set their PCP listening levels louder. This suggests that those working in noise may also opt for noisy leisure activity.
Currently, social noise exposure is mainly due to nightclubs. 11.3% had accumulated significant noise exposure from nightclubs, compared with only 3.2% from hi-fis, 2.0% from PCPs and 0.6% from live concerts. The measurements in local nightclubs (we are confident that the sound was not turned down for our benefit) suggest typical sound pressure levels of around 85-105 dB(A), and this agrees well with recent data from other areas of the UK. (Meecham and Hume 1998, personal communication).
The sound pressure levels we recorded in nightclubs are not significantly higher than they were in the late 1970s and 1980s. (Bickerdike and Gregory, 1980). The maximum levels they recorded at the speaker at that time was 102 dB(A) in licensed premises, and the mean Leq value they suggested for calculation of NIL was 97 dB(A). The mean attendance pattern in the present study, which was equivalent to one night a week (4 hours) corresponds with the attendance rates of Bickerdike and Gregory's "regular attenders." The number of people in the present study who attend "raves" which last for 12 hours or more is very small: 8 individuals (or 2.3%).
The MRC (1985) estimated in the early 1980s that 10% of those attending discotheques would accumulate significant social noise exposure by our definition. This was the lowest of a range of estimates given, and compares with 11.3% of the sample, or 12% of those attending discotheques in the present study. This latter figure is an underestimate because many of those in the present sample were still accumulating exposure. Consequently, the lower bound estimate by the MRC applies fairly well to the present habits of Nottingham residents.
Nightclubs are the principal cause of significant noise exposure in this age group, and also the most common cause of temporary dullness of hearing and of temporary tinnitus, as also found by Bradley et al (1987), and Hellstrom and Axelsson (1988). In the case of nightclubs and concerts, the sound level is outside the control of the listener. For PCPs or hi-fis subjects in the present study tended to set lower sound levels leading to less dullness of hearing and tinnitus. Our data are in agreement with Jolikulppo et al (1997), who report that approximately 30% people experience temporary tinnitus and 30% temporary hearing loss after attendance at a discotheque. As attendance at nightclubs with high levels of noise is often accompanied by consumption of alcohol, tobacco and recreational drugs, it may be that these other factors, either alone or in combination, have an effect on the auditory system. Further work is currently underway at this Institute to study these factors in more detail in a subset of the 18-25 year old population.
As so many individuals are exposed to potentially damaging noise, compared with either occupational or gunfire noise, and so many of them report temporary effects on their hearing particularly following nightclubs, then the next question to ask is whether this noise has any persistent effect on hearing or tinnitus. This question is addressed in a companion paper which shows that any effect of significant social noise exposure on hearing threshold levels is difficult to show. The question of the hearing of nightclub employees must also be raised, (as has Gunderson et al, 1997) as they are clearly at risk of damaging their hearing and employers may be required to take action to protect them. A study to consider the effects of noise on nightclub employees is needed.
Despite the lack of a significant effect on hearing threshold levels, consideration should be given to reducing sound levels in entertainment venues such as nightclubs. The reason for a lack of effect on hearing threshold levels, when exposures are equivalent to those known to cause effects from occupational noise, is unclear at present. However, this should not lead to complacency. One concern is that there may be subtle hair cell damage that has no effect on hearing threshold levels but may show up in supra-threshold tests like frequency resolution (West and Evans, 1990). Another is that subjects with noise exposure will experience age-related hearing problems earlier than the non-noise exposed subjects. General advice that may be helpful in reducing these possibilities concerns reducing the level of sound if possible, or time of exposure. Use of hearing protectors will be appropriate in some cases (eg musician's protectors). Setting maximum permissible levels for all types of social noise would be more difficult in practice, although a draft standard (EN 50332-1, 1999) is now available for measuring the output from PCP earphones, and so it may be possible to limit the sound pressure levels from PCPs. However PCPs are probably a low risk to hearing compared with nightclubs, at which it would be much more difficult to impose a maximum level.
It is clear that a high proportion of young adults attending nightclubs report temporary effects and this is often considered a pre-cursor to permanent effects (eg West and Evans, 1990). There are certainly public health issues surrounding these effects and another way to reduce the public health hazard is by educational means. To this end, the British Tinnitus Association has recently launched an Educational campaign called "Don't turn it off, turn it down". So far the campaign is aimed at 11-14 year olds, as a project for use in Personal and Social Education, and in Science teaching, and is a very welcome initiative.
| Conclusions|| |
Prevalence of significant social noise exposure has increased by a factor of three since the early 1980s, reaching 18.8% in the random sample of 18 to 25 year olds investigated in this study. In this context, significant noise exposure applies to those who have already accumulated a dose equivalent to 50 years working daily in a noise level of 80 dB(A). Alternatively, this may be expressed as a noise immission level of 97 dB(A).
The activity that leads to most noise immission is attendance at discotheques or nightclubs. This leads to temporary tinnitus and/or dullness of hearing in two-thirds of those attending. Further work is needed to quantify any persistent auditory effects in this sample, and to consider the implications for employees of discotheques and nightclubs.
Other common social activities giving rise to significant noise exposure to a lesser extent are hi-fis, PCPs and live rock concerts. None of these, or other activities that we investigated pose the same public health hazard as nightclubs/discotheques.
PCPs are used by virtually all teenagers or young adults at some stage, although only a few (2%) accumulate significant noise exposure from their use. However, 17% reported temporary effects following use of PCPs. From a public health perspective, the PCP is much less of a hearing hazard than nightclubs or discotheques.
| Acknowledgments|| |
Andrew Wade contributed to the data collection. Elizabeth Lovell helped with nightclub measurements.
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Pauline A Smith
MRC Institute of Hearing Research, Clinical Section, Ropewalk House, 113 The Ropewalk, Nottingham NG1 6HA
Source of Support: None, Conflict of Interest: None
[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5], [Figure - 6]
[Table - 1], [Table - 2], [Table - 3], [Table - 4], [Table - 5]