Age for PR and CL PMs ranged from 16 to 69 years, with no significant differences between the groups ( p = 0.78); 2914 (63.1%) of PMs included in the review were males; 1704 (36.9%) were females.

The articles selected for the review included a total of 4648 PMs, 3645 CL PMs (78.4%) and 973 PR PMs (20.9%); 30 subjects (0.7%) were excluded due to lack of details on the music genre played ( Figure 2 ).

Among these, 25 (60.9%) were prospective studies, 7 (17.1%) were case studies, 4 (9.8%) were cohort studies, 3 (7.4%) were longitudinal studies, 1 (2.4%) was a cross-sectional study, and 1 (2.4%) was a retrospective study. Twenty-six (63.5%) studies were conducted on CL PMs only, 11 (26.8%) on PR PMs only, and 4 (9.7%) on PR and CL PMs. Thirty-two (78.1%) studies reported details on the instruments played by the PM; in 9 studies (21.9%) the PMs were identified as PR or CL players but details about the instruments were not provided.

A total of 57 articles matching the inclusion criteria were identified. Among these, nine articles were excluded because they addressed other topics (= 2) or involved different populations (non-professional musicians= 3, singers= 2, music technicians= 1, general population= 1), and seven articles were excluded because they were centered exclusively on risk assessment without including details on specific hearing disorders. Following this selection, 41 articles were included in the review ( Figure 1 ).

3.2. Hearing Loss and Audiological Symptoms

HL (Pure tone threshold >25 dB at any frequency in the 250–8000 Hz range) was investigated in 41/42 (97.6%) articles included in the review (4507 PMs) and was found in 1742 subjects (38.6%). PR PMs were more affected compared to CL PMs, with respectively 547/862 (63.5%) and 1195/3645 (32.8%) subjects; the odds ratio for PR was 1.3991 (CI 95%: 0.4044–0.5441). The difference was statistically significant (χ: p < 0.0001).

HL affected prevalently the high frequencies in the range between 3000 and 6000 Hz. Among PR PMs, HL was reported for the 2000 Hz frequency in 16 (2.9%) subjects, 3000 Hz in 352 (64.3%), 4000 Hz in 370 (68.2%), 6000 Hz in 493 (90.1%), and 8000 Hz in 138 PMs (25.2%). In CL PMs, HL affected the 250 Hz frequency in 42 (3.5%) subjects, 500 Hz in 42 (3.5%), 2000 Hz in 74 (6.2%), 3000 Hz in 470 (39.3%), 4000 Hz in 712 (59.6%), 6000 Hz in 964 (80.7%), and 8000 Hz in 454 PMs (38%). Interestingly, no HL was reported for frequencies <2000 Hz for PR PMs. Details of HL in PMs are shown in Figure 3

p < 0.0001). HL was symmetric (thresholds for each ear within 15 dB of each other) in 835 PMs and asymmetric in 772 PMs. Characteristics on HL symmetry were not reported for 135 (7.7%) subjects (37 PR and 98 CL PMs). Symmetric HL was described in 347/510 (68%) PR PMs and in 488/1097 (44.5%) CL PMs; asymmetric hearing loss was present in 163 (32%) PR and in 609 (55.9%) CL PMs. CL PMs showed an odds ratio for asymmetric HL of 4.02 (CI 95%: 3.2574–4.9823). The difference between PR and CL PMs for asymmetric hearing loss was statistically significant (χ:< 0.0001). Figure 4 shows the percentage of symmetric and asymmetric HL in PMs.

n = 1628), followed by percussion ( n = 1050), brass ( n = 775), double bass ( n = 543), electric guitar ( n = 424), piano ( n = 314), flute ( n = 341), and trumpet ( n = 284). Details of affected frequencies in PMs sorted by instrument played are shown in The most common instruments were double bass, brass, flute, trumpet, percussion, strings, electric guitar, and piano. Although some are more commonly used by PR or CL PMs, in many cases they were used simultaneously in both genres. The highest extent of hearing loss was reported in PMs using strings (= 1628), followed by percussion (= 1050), brass (= 775), double bass (= 543), electric guitar (= 424), piano (= 314), flute (= 341), and trumpet (= 284). Details of affected frequencies in PMs sorted by instrument played are shown in Figure 5

Tinnitus was investigated in 17/41 (41.5%) studies including 2327 PMs (760 PR, 1567 CL) and was reported in 612 subjects (26.3%). Of those, tinnitus was found in 196/760 (25.8%) PR and in 416/1567 (26.5%) CL PMs. The odds ratio was 0.98 (CI 95%: 0.7616–1.131). No statistically significant difference was observed for tinnitus prevalence between CL and PR PMs (χ: p = 0.45).

Hyperacusis was evaluated in 8/41 studies (19.5%) including 791 PMs (288 PR, 503 CL) and was found in 172 musicians (21.7%). Of these, 77/288 (26.7%) were PR and 95/503 (18.9%) were CL PMs. The odds ratio was 1.56 (CI 95%: 1.1117–2.2095); the difference in the prevalence of hyperacusis between CL and PR was statistically significant (χ: p = 0.01) with increased risk for PR PMs.

Diplacusis was investigated in only 2 studies (4.5%) including 380 PMs and was found in 24 of them (6.3%), specifically in 4/139 (2.9%) PR and in 19/241 (7.9%) of CL PMs.