Dancing the
Aerobics "Hearing Loss Choreography"
Beatriz Pinto - beaporumtriz@hotmail.com Srgio Oliveira Popular version of paper 5pNSb4
This paper presents an overview of health clubs' acoustic problems when used
for aerobics exercise classes (and similar kinds of activity) which can have
very loud noise levels from sound-amplified music. Our analyses demonstrated
important risks for health club teachers in 80% of the situations and for the
students in 20% of the cases. Noise levels in each room were analyzed and values up to 96 dB(A) were found for the
standardized daily personal noise exposure levels and up to 123 dB for the peak
instantaneous values, inducing a health risk for its occupants. The benefits of regular physical activity are known and every day we see an
increase in the number of gymnasiums and health clubs. However, the acoustic
environments of the commercial spaces where that practice is possible are oftentimes
inadequate, leading to negative auditory effects. The exposure to high noise
levels for considerable periods of time may result in the reduction in hearing
sensitivity or even in hearing loss, not to mention possible health effects
outside the auditory system.
Antnio Carvalho - carvalho@fe.up.pt
Laboratory of Acoustics
College of Engineering, University of Porto
P-4200-465 Porto, Portugal
Instituto Superior da Maia
P-4475-690 Avioso S. Pedro, Portugal
Presented Friday afternoon, December 5, 2002
First Pan-American/Iberian Meeting on Acoustics, Cancun, Mexico
The acoustic problems of health clubs, when used for lessons of aerobics or
similar events, constitute the central subject of this work. The acoustic comfort
of the rooms for aerobics depends not only on the existing background music
but also on the physical characteristics of the rooms. They are usually very
reverberant spaces (closed and minimally absorbent spaces) where a sound source
(tape recorder or CD player) broadcasts high levels of sound. The long reverberation
times (RT) of the rooms the number of seconds that the sound takes
to naturally disappear in a room increase the sound level, constituting a kind
of natural amplification.The different RT of the rooms can also be an
indicative of the acoustics quality of this type of place.
A sample of several health clubs representative of this type of room was chosen
(in Portugal) for this survey but the situation is believed to be similar in
almost all other industrialized countries (Fig. 1 and 2). The rooms were analyzed
by measuring the sound levels of the music during the lessons and the reverberation
times.
An aerobics lesson is typically divided in three phases: the "warm up" (duration
of about 12 minutes), the "choreography" (duration of about 40 minutes) and
the "cool down" (duration of about 8 minutes). The ranges of measured sound
levels are displayed in Table 1 for each part of the lesson. Differences were
found that are caused by varying intensities of the emitted music.
Therefore, the students will be exposed to high sound pressure levels of up
to 102 dB(A) for about an hour, aggravating the situation for the teacher who
is exposed to about 3 hours.
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Phase
1 - warm up (12 min)
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from
88 to96 dB(A)
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Phase
2 - choreography (40 min)
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from
88 to 102 dB(A)
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Phase
3 - cool down (8 min)
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from
88 to96 dB(A)
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Entire
class (60 min)
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from
88 to 100 dB(A)
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With 85 dB(A) the maximum legal value in the European Union (EU) for which
an intervention is needed, a "comfort" maximum value of 80 dB(A) is suggested
for these spaces.
Regarding the instantaneous peak sound pressure levels, the maximum legal limit
in the EU of 140 dB is not reached but very high values up to 123 dB were measured.
The instantaneous peak limit for comfort situations is suggested to be set as
100 dB.
Facing the general non-compliance of the desired requirements for acoustic
comfort, a maximum limit value for the sound level during each lesson was suggested
as 85 dB(A) to contemplate the auditory health of the persons exposed to high
noise during the classes.
This value during each class is easily obtained by lowering the music sound
level from 4 to 16 dB(A) of the current existing values. The music would still
remain high enough to give the much-needed sonorous stimulation to those who
practice or teach this type of lesson.
Room Characteristics
Determining the acoustic characteristics of the rooms was made by measuring the reverberation
time (RT). The measured values from 0.9 to 2.8 s clearly
differentiate between good and acoustically inadequate rooms and are,
in general, relatively high, a direct consequence of the large room volume with
surfaces typically lacking sound absorbent material.
When
comparing the measured values with the ones in the legislation for several European
countries for similar spaces (especially school gymnasiums) with maximum values
from 1.2 to 2.1 s, there is an almost generalized non-compliance.
However it is possible to correct the reverberation time with simple measures.A maximum reverberation time of 1.5 s was found appropriate for an ideal maximum for this type of space. Such a value is perfectly possible to be reached with the use of sound absorptive material (to coat total or partially the ceiling, for instance).In the tested sample of health clubs the ceiling area that it would have to be covered by absorptive material was found to be between 50% and 100% of its total.
The existing general situation is summarized in Table 2 with the range of values
found and a set of ideal design goals defined
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Very
high values in many situations
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Generally
high values because the legal limit is 85 dB(A) and the suggested comfort
limit is 80 dB(A)
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High
values (but within legal limits) that surpass the proposed comfort limit
of 100 dB
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Generally
high values potentially causing acoustic discomfort
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Ceiling
area to be covered with sound absorptive material
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