BMC Public Health 2008, 8:151 http://www.biomedcentral.com/1471-2458/8/151 Table 2: Characterization of subjects according to the hours worked per day, length of time working and use of hearing protectors. Distribution of participants of the sound professionals group Variables Hours worked/day < 6 hours 6 to 12 hours > 12 hours 5.0 to 14.9 15.0 to 24.9 25.0 to 34.9 35.0 to 45.0 Average ± SD Use of hearing protectors No Yes Length of time working as sound technicians Frequency 24 47 11 39 30 11 2 70 12 15.9 ± 8.8 % 29.3 57.3 13.4 47.6 36.6 13.4 2.4 85.4 14.6 [32], such workers may mention that they have this symp- tom at times of hearing rest. It was found in our study that there was a statistically significant difference in the pres- ence of tinnitus between the sound technician and control groups (p < 0.001), i.e. there was greater reporting of tin- nitus among the sound technicians (Table 1). One example of this situation of noise exposure over a long period of time is provided by the British guitar player and singer Eric Clapton (age 62 years), who developed tinnitus after spending years of his career playing in front of sound amplifiers at high volumes. He has said that, if he could go back in time, he would ask to have lower amplifier volume during his concerts. He has reported that he constantly hears "whistles" in his ears [33]. Another example that illustrates this situation within Bra- zilian popular music is provided by the vocalist of the group Jota Quest, Rogério Flausino, who is only 35 years old. In a documentary that forms part of the band's latest DVD, he reveals that he has lost 30% of his hearing because of many years living with high sound volumes Table 3: Distribution of participants according to the presence of hearing loss. [34]. Andrade et al (2000) [19] confirmed a possible asso- ciation between the length of time working as a musician and the incidence of hearing alterations. The main outcome of the present study was the presence of hearing loss. With regard to this, there was a statistically significant difference (p < 0.001) between the sound tech- nicians and controls (50% versus 10.5%, respectively) (Table 3), thus revealing that hearing loss occurred approximately five times more frequently in the sound technician group. The difference could be addressed to high sound levels. The effect of music on sound technicians' hearing was found to be greater in the present study than in other stud- ies such as Cunningham (2006) [16]. This was perhaps because most of the sound technicians evaluated in the present study work or were working in open-air events, i.e. in places where the sound level is extremely higher and harmful. Variable No Yes Presence of hearing loss aChi-square test Sound technicians Controls N = 82 41 41 % 50.0 50.0 N = 95 85 10 % 89.5 10.5 p <0.001a Page 6 of 8 (page number not for citation purposes)