First Pan-American/Iberian Meeting on Acoustics, Cancun

Dancing the Aerobics "Hearing Loss Choreography"

Beatriz Pinto -
Antnio Carvalho -
Laboratory of Acoustics
College of Engineering, University of Porto
P-4200-465 Porto, Portugal

Srgio Oliveira
Instituto Superior da Maia
P-4475-690 Avioso S. Pedro, Portugal

Popular version of paper 5pNSb4
Presented Friday afternoon, December 5, 2002
First Pan-American/Iberian Meeting on Acoustics, Cancun, Mexico

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.

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.

Figures 1 and 2- Images of two of the rooms tested.

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.

Table 1 Sound levels during lessons for each class phase.
Sound Levels during lessons
Range of measured values
Average of all sampled health clubs
Phase 1 - warm up (12 min)
from 88 to96 dB(A)
92 dB(A)
Phase 2 - choreography (40 min)
from 88 to 102 dB(A)
94 dB(A)
Phase 3 - cool down (8 min)
from 88 to96 dB(A)
92 dB(A)
Entire class (60 min)
from 88 to 100 dB(A)
93 dB(A)

The daily personal noise exposure [a standardized measure of the noise that the person is exposed over a nominal eight-hour workday] was calculated for teachers with 3 hours of lessons and students with 1 hour of lessons (however, currently, a significant number of students remains for more than 1 hour in a health club, for example by taking two consecutive lessons). The calculated results for the teachers were from 84 to 96 dB(A) and for students from 79 to 91 dB(A) when the legislation stipulates that the daily personal noise exposure level should not exceed 85 dB(A). Therefore, the analyses demonstrated important risks for the health club teachers in 80% of the situations and for the students in 20% of the cases.

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

Table 2 Summary of the sampled situation and the proposed ideal design goals.
Range of measured values
Proposed limit values for comfort
Sound level
88 - 102 dB(A)
85 dB(A)
Very high values in many situations
Daily dose
79 - 96 dB(A)
80 dB(A)
Generally high values because the legal limit is 85 dB(A) and the suggested comfort limit is 80 dB(A)
Peak value
114 - 123 dB
100 dB
High values (but within legal limits) that surpass the proposed comfort limit of 100 dB
Reverb. time
0.9 2.5 s
1.5 s
Generally high values potentially causing acoustic discomfort
Sound absorption (% ceiling area)
50% - 80%
Ceiling area to be covered with sound absorptive material


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