Association between leisure noise exposure and hearing status in young Croatian adults

Table 1 shows participant demographics and health data. Young men and women differed significantly in age and education but not in medical history or otoscopy findings. Otoscopic examination revealed that only 25.1 % of participants had cerumen in one or both ears. The most common reported chronic disease was an allergy.

We also found no gender differences in the hearing status of our participants (Table 2). Around half reported having hearing symptoms such as tinnitus, pain in the ear, and sensitivity to noise. Subjective perception of slightly impaired hearing (self-classified as average) was reported by nine women (13.9 %) and no man. Audiometry revealed mild sensorineural hearing loss in either right or left ear in one man (2.3 %) and five women (7.7 %), making up 5.5 % of all participants. The mean hearing threshold in both ears in both groups ranged between 11.2 and 13.5 dB.

However, gender differences came to the fore in headphones/speakers use (Table 3), most notably in the total use time a day, especially in gaming. More women reported to prefer headphones, especially the in-ear type, but did not differ from men in the subjective perception of high headphones/speakers volume (self-reported as cannot hear background traffic and conversation) while listening to music or gaming. However, the average measured headphones volume (dB) was significantly higher in men than in women, exceeding the >70 dB continuous exposure limit in 27.7 % of women and 52.2 % of men (p=0.009). Given that the average time of headphones/speakers use was 1.9±1.2 h in men and 1.3±0.8 h in women, our participants were still below the WHO risk threshold of developing hearing loss, yet the majority self-assessed some level of hearing loss risk (Table 4). Most women (61.4 %) assessed low risk, while men equally (37.2 %) assessed medium and low risk. Self-reported time spent in recreational noisy venues (loud places) did not differ between genders (12.8±8.0 h/month for men vs 11.3±7.4 h/month for women).

We did not find any significant correlation between the hearing threshold and objectively measured headphones volume, total daily time of using headphones/speakers or time spent at loud places. We also did not find any significant difference in the hearing threshold between participants who listened to music with headphones/speakers at volumes above and below the 70 dB limit.

Participants who reported to use headphones/speakers at higher volumes to cancel background noise (cannot hear background traffic or conversation) also used headphones/speakers significantly more often than those who did not report increasing the headphones/speakers volume to cancel background noise (p=0.004). Furthermore, participants who reported exposure to higher volume also had significantly higher headphone volume measured by Verifit than those who reported listening to music at lower volumes (p<0.001). Participants who assessed their hearing as average had significantly higher hearing threshold than those who assessed their hearing as good (13.1 vs.11.7 dB) (p=0.036).

In our young population aged 18–28 years, the prevalence of mild sensorineural hearing loss was 5.5 %. Although there are numerous studies on hearing impairment in young people, many do not show prevalence. In the United States, the overall prevalence of hearing loss among 6–19-year-olds, exceeding 15 dB in either ear, was 11.24 % in the past decade (24). In Slovakia, audiometry testing in 41 young university students showed a shift in hearing threshold at higher frequencies (8000 Hz) in 22 % of participants (17). In Poland, a small study in 58 young adults (19) reported noise-induced hearing loss in 6.9 % and another (25) in 4.2 %, this time in a much larger sample of 230 students.

However, most of our participants (75 %) with objectively measured hearing impairment reported no subjective experience of hearing loss, which suggests that young adults hardly notice mild hearing impairments, as they do not significantly impair their quality of life.

Those who reported listening to music at louder volumes to cancel background noise (questionnaire item: cannot hear the background traffic and conversation) also reported to use headphones/speakers significantly more often than those who reported applying lower volumes. This indicates that young people who practice unsafe use of headphones/speakers and do not have objective hearing impairment may still run a significant risk for later hearing loss development.

Our participants who reported a slight hearing loss (classified as average hearing) also had a higher hearing threshold (indicative of loss) than those who reported good hearing. This suggests that the subjective feeling of hearing impairment may predict its actual development later in life. People who subjectively feel that their hearing is impaired are probably more prone to subtle cochlear damage and may experience hearing problems undetected by standard audiometry (26, 27).

Although we did not find a correlation between time spent in noisy places and either subjective or objective hearing loss, a number of studies (7, 28,29,30,31) warn of transient hearing loss and tinnitus immediately after exposure in such venues and the risk of later permanent damage.

Average time spent on recreational use of headphones in all our participants, either for listening to music or gaming, was 1.5±1.1 h/day, which is similar to some other studies reporting up to two hours of use per day (16, 25). Mean values of sound pressure in the headphones of 66.5 dB in our participants did not exceed the recommended exposure levels of 70.0 dB, although the values in men were borderline. Such exposure is well below the high risk threshold of >90 dB for headphone volumes indicated by most studies (13, 32).

Our results also showed no significant correlation between headphone volume and the shift in the hearing threshold as indicator of hearing impairment. This is in line with some studies (33), including the recent review of 20 articles (34) that find no clear relationship between recreational noise activities and harmful effects on hearing (33, 34). However, other studies clearly evidence the negative effects of headphones/speakers on the auditory system (16,17,18). One interesting finding, published by Pawlaczyk-Łuszczyńska et al. (19), was worse hearing in irregular headphones users than the regular ones. All those discrepancies in findings might be owed to different methods of measuring exposure and outcome between studies.

Gender differences in listening volume found in our participants confirmed reports of several other studies, and it seems that men prefer louder music than women (32, 35, 36). However, we found no significant gender differences in objective hearing parameters, which is also in line with some earlier reports (36,37,38).

The interpretation of our findings is somewhat limited due to a relatively small sample and cross-sectional design, which does not allow establishing a definitive association between hearing loss and exposure to recreational noise. However, our objective audiometric assessment of hearing and objective measure of sound volume in the headphones are reliable enough to draw some conclusions.

The advantage of our study is that it relies on objective assessment, including audiometry and direct measurement of listening volume through headphones/speakers. It also puts together data on recreational exposure to noise through headphones and visits to loud recreational venues. Although most young people in our study are not exposed to excessive noise on average, the findings still point to long-term risks of noise-induced hearing loss, given that one-third perceive themselves to be at moderate or high risk of developing hearing impairment.

Another curious finding are differences in listening habits between genders, most notably that young men expose themselves to higher levels of recreational noise. However, consequences of such behaviour are not apparent yet, as we have found no differences in objective hearing loss distribution between the genders.