# Acoustic Environment and Noise Exposure in Fitness Halls
## 1 Introduction  
In recent years, fitness gyms and indoor sports and gymasium (IS & G) centers have become highly popular places for people seeking physical fitness and a healthy lifestyle. IS & G centers have large spaces with large areas of reflective parallel surfaces. When sound hits these reflective surfaces, it bounces back into the hall and can lead to echoes, focusing, and standing waves. Flutter echoes can occur as a result of the parallel walls, significantly increasing the reverberation time and reducing speech intelligibility [1; 2; 3]. Speakers increase their vocal effort and raise their voices when speaking in a noisy environment to enhance the audibility of their voice and to maintain good communication with others [4; 5]. Most IS & G centers play music at a high volume as an integral feature of group exercise. Previous studies [6] have demonstrated that instructors and users believe that loud music stimulates physical activity and enhances performance. Furthermore, studies have also demonstrated that interacting with loud music with a fast beat and/or tempo plays a significant role in enhancing exercise performance and motivating those attending fitness classes [7; 8; 9]. For instructors, the gym hall is characterized as an occupational environment, whereas for users, it is a leisure environment. Although the main purpose of fitness gyms is to improve the users' physical fitness and quality of life, such an environment with excessive exposure to loud music can be harmful to both instructors' and users' hearing [10; 11; 12; 13]. Assessments of noise exposure in sports instructors have shown very high continuous equivalent sound pressure levels [14]. In addition, studies have investigated risks related to noise exposure, symptoms of hearing loss, and awareness of hearing problems among fitness instructors [15; 16; 17; 18; 19]. The results from a recent study [20] showed that morethan half of fitness instructors were potentially exposed to excess noise and had signs and symptoms of hearing loss. Other investigators [21; 22; 23] also demonstrated that sports instructors have voice problems. Furthermore, the potential risk of noise-induced hearing loss (NIHL) due to loud music exposure [24] has been widely investigated in musicians and people working in music venues [25], students studying music [26], and people listening to loud music in leisure venues [27]. In general, noise sensitivity was found to significantly affect physiological responses [28]. Indoor ambient noise and noise exposure of physical education teachers were also studied [29; 30] and results showed that fitness instructors are a high-risk population for vocal troubles, with 55% reporting that they experienced voice difficulties. In addition, the comfort levels of people in large interior spaces with complicated acoustical characteristics have also been investigated, and studies concluded that the acoustic environment has a negative impact on people's emotions, attention, and thinking ability [15; 31; 32; 33]. Considering the above, the acoustic design and qualities of fitness gyms and indoor sports halls have become integral parts of their structural design that are closely monitored and regulated by international standards. Specific standards for noise levels and reverberation time (\(T\)) for IS & G centers have been introduced in the Building Bulletin standards, BB version 17 issued in 2015 [1], and by experts in the field [34]. Criteria and allowable limits of recommended exposure levels (RELs) for occupational noise exposure have been introduced by the National Institute for Occupational Safety and Health (NIOSH) [35]. Similarly, the Occupational Safety and Health Administration (OSHA), the International Organization for Standardization (ISO-1999) [36], and the European Union Directive [37] have also established permissible exposure limits (PELs) of noise level at different settings.