# Acoustic Environment and Noise Exposure in Fitness Halls
## 2 Methods
### Noise Level Measurements in IS & G Halls  
Following international standards adopted in the United Kingdom by BB [1], the evaluation of ambient noise was performed in non-occupied, but furnished IS & G halls with doors closed, but windows open, and without any ongoing activities inside the hall. Measurements were conducted using an XL2 Acoustic Analyzer and a Class I NTi Audio M2230 (NTI Audio AG, Schaan, Liechtenstein) sound level meter placed on a tripod at a height of 1.50 m from the floor and at least 1.5 m away from the surrounding reflective surfaces. The JAC indicates that only the continuous equivalent sound level L\({}_{\text{A,eq}}\) should not exceed 40.0 dB(A), and does not establish the duration of the measurements; the L\({}_{\text{A,eq}}\) measurement time was 30 min, thus characterizing the L\({}_{\text{A,eq, 30 min}}\) dB(A) as prescribed by Building Bulletin (BB) [1]. L\({}_{\text{A,eq, 30 min}}\) was measured twice per day: early in the morning (05:30-06:30) after opening the IS & G centers and before users arrived, and during the lunch break (14:00-15:00).  
The activity noise levels (L\({}_{\text{A,eq}}\)) were measured in occupied IS & G halls during workout lessons; the music is played in all cases. The L\({}_{\text{A,eq}}\) was measured using an XL2 Acoustic Analyzer and a Class I NTi Audio M2230 sound level meter placed on a tripod at a height of 1.20 m from the floor, at the typical instructor's position and not close to the loudspeakers, as illustrated in Figure 2. The workout session lasted for 60 min, and measurements of the equivalent continuous A-weighted sound pressure level, L\({}_{\text{A,eq}}\), were taken for 50 min, because this is the duration of a workout session with loud music. The last 10 min of each session is for relaxation, usually accompanied by medium- to low-volume music. Hence, L\({}_{\text{A,eq}}\) was not measured during the last 10 min of the workout sessions. Three measurements of activity noise levels were measured per day during the sessions in each IS & G hall. Equivalent sound pressure levels were obtained for each record, and then the equivalent of the three measurements in each IS & G hall was calculated.  
The dose per day, as a percentage, for the instructor's exposure to occupational noise during the time they are delivering workout classes, was determined using Expression (1) [38]:  
\[D=100\sum C_{\text{n}}/T_{\text{n}} \tag{1}\]  
where \(D\) is the dose (%), C\({}_{\text{n}}\) is actual hours at a certain sound level, and T\({}_{\text{n}}\) is the allowable time for that sound level. Allowable noise exposure time T\({}_{\text{n}}\) was taken from [38]. It is acceptable to have the dose less than 100%, where exceeding 100% means exceeding the maximum permissible daily exposure time. The workplace noise assessment, L\({}_{\text{A,eq}}\)[41], is known as L\({}_{\text{EX, 8 h}}\) in the Physical Agents (Noise)  
Figure 1: Representative photos taken during measurements of reverberation time and noise levels inside the studied indoor sports and gymnasium (IS & G) halls.  
Directive [37]. Therefore, Expression (2) is used to calculate \(\mathrm{L_{EX,\,8\,h}}\)[41] from information about noise exposure levels during sub-periods:  
\[\mathrm{L_{EX,\,8\,h}}=10\times\log 1/\mathrm{T}\ (t_{1}\times 10^{L_{1}/10}+t_{2} \times 10^{L_{2}/10}) \tag{2}\]  
where \(L_{1}\) and \(L_{2}\) are the equivalent sound pressure levels during the two sub periods, \(t_{1}\) and \(t_{2}\) are the time periods for which these levels are maintained, and T is the overall time period. T must be equal to the sum of \(t_{1}\) and \(t_{2}\) sub periods of four hours were considered: \(t_{1}\) equals four hours with activity noise and \(t_{2}\) equals four hours without activity noise (i.e., only indoor background ambient noise).