Download Jokitulppo Jaana. Manuscript is based on doctoral thesis of: Non

Jokitulppo Jaana. Manuscript is based on doctoral thesis of: Non Occupational Noise - Sources,
Exposure and Effects on Hearing. Kuopio University Publications C.Natural and Environmental
Sciences 254, 2009, 110 p.
Author´s address:
Akukon Consulting Limited, Saranpääntie 9, FIN-90460 Oulunsalo, Finland
Tel. +358 50 5337781, Fax +358 9 15171711
Email: [email protected]
INTRODUCTION
Noise is probably the most widespread problem in the environment. The increase of noise problems
has been caused especially by traffic growth and technical development. The growth in noise
pollution is unsustainable, because it involves direct, as well as cumulative adverse health effects. It
also adversely affects future generations, and has socio-cultural, esthetical and economical effects.
The technical development and economical well being have provided both available time and
various ways to spend leisure time. Modern people are also eager to have experiences and changes
easily the way to spend leisure time.
Today, our society is highly diverse and continuously active, demanding interaction and
communication among individuals and between groups of people. Despite technical development,
speaking is the fastest and the most used way to communicate, and this requires good hearing
capacity to succeed. Hearing loss, with the accompanying effects, is one the most glaring, yet
misunderstood deficits; it can severely impair or even stop the communicative process, which has
detrimental effect on psycho-social behaviour and well-being. It has also effect on choices and
ability of education and work.
There seem to be several noisy leisure-time activities, which have high equivalent noise levels, up
to 100 dB or even more. Rock-concerts and discotheques sound levels are at minimum between 90
and 100 dB. The musical instruments' sound levels vary between 75-100 dB. Sports, such as
shooting and hunting include high energy impulsive type of noise of equivalent levels easily over
100 dB. Motor sports and home tools can also produce sound levels of 70-110 dB. Also many
events, such as sport games include powerful music, but also sound of audiences and their cheering
equipment such as drums, whistles etc. produces high sound levels into the environment.
Equivalent sound levels of personal stereos vary mainly between 70 and 83 dB. However, 5-15% of
listeners seem to choose sound levels that are over 85 dB. Despite of the limiters, most of the
equipment could emit maximum sound levels of 90-105 dB, or even more. Risk for hearing loss
among the users of personal music listening equipment is for those who listen on a daily basis and
listen in noisy environments. Also fireworks, toys and games sound levels can include risk for
hearing early at childhood.
There are no specific methods to evaluate of leisure time noise exposure on overall. At the present
situation, the only way to evaluate the weekly leisure time noise exposure is based on occupational
noise limits and standards, which are intended only to estimate the adverse effect to hearing (EU
10/2003; ISO 1999). The risk of noise exposure during the leisure time has not been studied in its
entirety. The studies have considered either young people or certain employee working at the music
or entertainment industry. There is not an evaluation of the total noise exposure of all the activities
combined. In addition, there is no data available of life-time noise exposure. However, the auditory
symptoms related to leisure time noise exposure have been less studied.
METHODS
The objective of the study was to evaluate the total risk for hearing loss related to leisure time noise
activities during the lifetime in Finland. The total combined lifetime leisure time noise exposure of
all the activities was calculated and the hearing thresholds of conscripts at the beginning and at the
end of the military service was measured. Furthermore, the effect of military service to hearing was
evaluated. Also the aim of the study was to find those leisure time activities, which had most effect
on total leisure time noise exposure. In addition, the effects of personal leisure time noise exposure
on hearing thresholds and self-reported auditory symptoms related to noise exposure was
determined. Hearing loss was defined as thresholds greater than 20 dB in one or more frequencies
for one or both ears according to the following categorization:
Hearing category
Hearing threshold
1:
Normal hearing, ≤ 20 dB in both ears over all frequencies. If one of these criteria is not fulfilled
the actual thresholds should be determined over all the frequencies.
2:
≤ 20 dB over speech frequency (0.5–1-2 kHz), up to 40 dB at 3 kHz or up to 65 dB at 4 kHz.
3:
Average hearing threshold over 20 dB in the speech frequencies but a hearing threshold exceeds
40 dB at 3 kHz or 65 dB at 4 kHz.
4:
Average hearing threshold ≥ 20 dB also in the speech frequencies
This study was performed among teenagers, conscripts and adults with the use of a leisure time
noise exposure questionnaire. The weekly noise exposures of a single activity and all activities
combined was calculated and compared to occupational noise legislation (EU 10/2003), because
there is no separate evaluation model for leisure time noise.
RESULTS
The greatest noise exposure was gathered with regular attendance on discotheques and music bars.
In addition, shooting, playing in a band or an orchestra, use of noisy home tools and attending
motor sports included a risk of noise induced hearing loss (Fig.1.). On the whole, the total weekly
noise exposure was formed by various noisy leisure time activities. The less noisy activities such as
listening to music and watching television may perform the basic exposure level. This means that
there might not be adequate silent breaks after exposure to noisiest activities, such as going to a
concert or disco.
Total weekly noise exposure exceeded 85 dB in one third of the teenagers and the conscripts and in
one fifth of the adults (Fig.2). One out of five conscripts had already reached the noise exposure
similar to the noise exposure of 85 dB for 40 years by the end of their conscription. Most of this
noise was gathered from military noise exposure during the conscription. Average hours used on
noisy leisure time per week varied due to the age of the study subject. Teenagers and conscripts
spent more such hours compared to adults. Young people used about 15-16 hours more on their
noisy leisure time activities compared to adults. The total time usage decreased after the age of 30
years. In general, teenagers and young adults under 30 years of age spend similar amount of hours
as 40 hour working week at noisy activities during their leisure time.
Approximately one in five of the conscripts (19%) had a hearing impairment (HI) of over 20 dB in
either ear in the frequency range of 0.5-6 kHz during the arrival examination. Most of the hearing
losses were mild types (category 2). By the end of the military service the prevalence of hearing
loss was increased into one in three of the conscripts (27%). The statistically significant correlations
was found between exposure to noise from pistols and machine guns, and both right ear at
frequencies at 1-4 kHz and left ear at frequencies at 0.5-3 kHz. Also exposure to noise from 120mm mortars correlated with hearing impairment in the right ear at 6 kHz.
Tinnitus (teenagers and conscripts over 70%) and temporary hearing impairment (teenagers and
conscripts about 50%, over 10% adults) were common auditory symptoms in subjects of all
investigated groups. These symptoms were most common in individuals with high personal weekly
noise exposure.
Figure 1. Percentage of people exposed to over 85 dB by age groups.
weekly noise exposure over 85 dB
weekly noise exposure over 75 dB
weekly noise exposure over 80 dB
% of people exposed
90
77
80
70
56
60
32
27
30
54
52
45
38
34
68
53
50
50
40
73
69
18
20
34
31
20
10
0
12-16
19-20
25-29
30-39
40-49
50+
age group
Figure 2. Total weekly noise exposure comparison among all age groups.
The conscripts who had attended shooting at their leisure time before the military service, had
statistically (p< 0.01) worse hearing than people who had not. Either type of 2, 3 or 4 hearing
category was measured with 29% of shooters, but 18% of the non-shooters group. All of those
having hearing impairment were 20% of shooters. However, the shooters had more often left ear
hearing loss at frequencies of 4-8 kHz (p≤ 0,001) compared to those who did not attend shooting.
There was no similar difference among other leisure time activities. The difference among shooters
compared to others was not seen any longer during the leaving examination.
DISCUSSION
Highest sound levels of leisure-time activities were mainly related to places or activities where
electronic amplified music is played, such as discos, concerts, music festivals, playing in a band or
an orchestra and sports events. The attendance on discotheques and music bars had most effect on
personal weekly noise exposures to all subjects at any age. Furthermore, home tools and equipment
used indoors and outdoors and motor sports and shooting were also activities which had effect on
the weekly noise exposure among all the investigated groups. Daily listening to music via personal
stereos seemed not to cause high exposure noise levels for most of the subjects, but there seemed to
be 2 % marginal group of “super-listeners” who listened to music several hours per week and also
according to their own report with very high sound levels.
The results of arrival study seem to confirm the hypothesis that the most probable cause of HI in
young men is related to the leisure time noise exposure. In addition, although the time of the
military service is short, the exposure to very high military noise levels during that time has further
deleterious effects on the hearing of the young men. However, the most probable reason for the
increase of hearing losses was related to the noise exposure of a pistols and machine guns shot
without hearing protectors during combat exercise.
The personal preference of leisure time activities changes over lifetime. Very active people attend
several noisy activities weekly during their lifetime and increase their risk for hearing loss
remarkably. Every third of teenagers and young men at their early twenties, and every fifth of the
adults are at risk of having a hearing loss from the noise they are exposed to at their leisure time. On
the whole, at least one out of five persons seems to be under a risk of a hearing loss due to leisure
time noise exposure during their whole lifetime. At overall, the high incidence of hearing symptoms
and hearing loss with noise high exposure levels seems to confirm the assumption that leisure-time
noise exposure is a significant factor of the development of NIHL.
The auditory symptoms such as tinnitus and temporary hearing loss should be regarded as warning
signals of exposure to too high levels of noise. These symptoms should be routinely asked in the
health examination of all age groups. The method performed in this study is usable for evaluation of
the total leisure time noise exposure of several people. In addition, possible risk groups of high
leisure-time noise exposed subjects could be screened for further health examinations. Personal
noise exposure measurements should be provided for individual assessments. Early screening of
hearing loss is important for avoiding further development of hearing loss at any age.
The use of hearing protectors is highly recommended during the activities where sound level is over
80 dB. With sound equipments used close to the ear, the volume levels should be decreased by
more effective limiters by legislation. Furthermore, the legislation to control the noise levels among
leisure time should be proceeded, especially regarding events where children and young people are
in the audience. Information about the risks of noisy leisure time activities on hearing should be
provided to authorities, event arrangers, music industry workers, teachers, trainers, and people who
daily meet young people. Educational programs should be provided in schools. These could be
integrated to health and music classes. In addition, the public information about the effects of
leisure time noise should be provided especially for health organisations and to parents who are
responsible for their children's health.