Occupational noise exposure and tinnitus: the HUNT Study

Figures & data

Table 1. Characteristics of 14,945 participants in different exposure groups in HUNT4 Hearing (2017–2019), Norway.

	JEM-based noise exposure			Total, N (%)
	Low exposed N (%)	Moderately exposed N (%)	Highly exposed N (%)
Total	8912 (100)	5081 (100)	952 (100)	14,945 (100)
Age, mean ± SD	42.6 ± 11.4	40.9 ± 11.1	50.0 ± 7.9	42.5 ± 11.3
Men	2620 (29.4)	2736 (53.9)	889 (93.4)	6245 (41.8)
Normal hearing^a	8037 (90.2)	4450 (87.6)	656 (68.9)	13,143 (87.9)
Elevated hearing thresholds^a	875 (9.8)	631 (12.4)	296 (31.1)	1802 (12.1)
Feeling nervous/uneasy last 2 weeks	3822 (42.9)	2165 (42.6)	312 (32.8)	6299 (42.2)
Lower education	3286 (36.9)	3273 (64.4)	781 (82.0)	7340 (49.1)
Head injury	539 (6.1)	379 (7.5)	74 (7.8)	992 (6.6)
Leisure noise, earphones at loud volume >6 h/week	205 (2.3)	168 (3.3)	10 (1.1)	383 (2.6)
Leisure impulse noise (shooting, fireworks, etc)	3298 (37.0)	2437 (48.0)	625 (65.7)	6360 (42.6)
Years of unemployment (2000–2017), mean ± SD	2.3 ± 2.9	2.3 ± 2.7	1.1 ± 2.0^b	2.2 ± 2.8
Smoking history	4176 (46.9)	2761 (54.3)	548 (57.6)	7485 (50.1)
Reports always using hearing protection^c	229 (2.6)	655 (12.9)	239 (25.1)	1123 (7.5)
	Self-reported noise exposure^d			Total^d, N (%)
	Low exposed N (%)	Moderately exposed N (%)	Highly exposed N (%)
Total	10,802 (100)	3074 (100)	902 (100)	14,778 (100)
Age, mean ± SD	42.5 ± 11.2	41.3 ± 11.6	46.5 ± 9.5	42.5 ± 11.3
Men	3475 (32.2)	2057 (66.9)	638 (70.7)	6170 (41.8)
Normal hearing^a	9721 (90.0)	2608 (84.8)	664 (73.6)	12,993 (87.9)
Elevated hearing thresholds^a	1081 (10.0)	466 (15.2)	238 (26.4)	1785 (12.1)
Feeling nervous/uneasy last 2 weeks	4491 (41.6)	1349 (43.9)	392 (43.5)	6232 (42.2)
Lower education	4593 (42.5)	1971 (64.1)	667 (74.0)	7231 (48.9)
Head injury	631 (5.8)	265 (8.6)	87 (9.7)	983 (6.7)
Leisure noise, earphones at loud volume >6 h/week	236 (2.2)	112 (3.6)	32 (3.6)	380 (2.6)
Leisure impulse noise (shooting, fireworks, etc)	3958 (36.6)	1791 (58.3)	546 (60.5)	6295 (42.6)
Years of unemployment (2000–2017), mean ± SD	2.2 ± 2.8	2.2 ± 2.7	1.9 ± 2.7 ^b	2.2 ± 2.8
Smoking history	5126 (47.5)	1703 (55.4)	562 (62.3)	7391 (50.0)
Reports always using hearing protection^c	74 (0.7)	711 (23.1)	320 (35.5)	1105 (7.5)

Information is based on HUNT4 (questionnaires or examination) and a JEM (job exposure matrix). Exposure categories, JEM: low = no exposure ≥80 dB; high = minimum 5 years ≥85 dB; moderate = not fulfilling criteria for low or highly exposed. Exposure categories, self-report: low = no prior exposure; high = >15 h/week ≥5 years; moderate = not fulfilling criteria for low or highly exposed.

^aElevated hearing thresholds = thresholds at 3–6 kHz (mean of both ears) > 25 dB. Normal hearing = remaining participants.

^bThe highly exposed categories (JEM and self-report) include time criteria (at least 5 years of exposure), which should be kept in mind when comparing different exposure categories.

^cAnswered “always” to the question: “Did you use hearing protection.” (Instead of “often,” “seldom/never” or “not applicable.”)

^dParticipants with missing information about self-reported noise exposure (N = 167) were excluded.

Table 2. Crude prevalence of tinnitus among 14,945 participants, stratified by noise exposure and hearing status, in HUNT4 Hearing (2017–2019), Norway.

	JEM-based noise exposure
	Low exposed, N (%)	Moderately exposed, N (%)	Highly exposed, N (%)	Total, N (%)
Normal hearing^a	360 (4.5)	182 (4.1)	40 (6.1)	582 (4.4)
Elevated hearing thresholds^a	203 (23.2)	126 (20.0)	62 (21.0)	391 (21.7)
Total	563 (6.3)	308 (6.1)	102 (10.7)	973 (6.5)
	Self-reported noise exposure^b
	Low exposed, N (%)	Moderately exposed, N (%)	Highly exposed, N (%)	Total^b, N (%)
Normal hearing^a	394 (4.1)	148 (5.7)	36 (5.4)	578 (4.5)
Elevated hearing thresholds^a	211 (19.5)	111 (23.8)	67 (28.2)	389 (21.8)
Total	605 (5.6)	259 (8.4)	103 (11.4)	967 (6.5)

Information is based on HUNT4 (questionnaires or examination) and a JEM (job exposure matrix). Exposure categories, JEM: low = no exposure ≥80 dB; high = minimum 5 years ≥ 85 dB; moderate = not fulfilling criteria for low or highly exposed. Exposure categories, self-report: low = no prior exposure; high = >15 h/week ≥5 years; moderate = not fulfilling criteria for low or highly exposed.

^aElevated hearing thresholds = thresholds at 3–6 kHz (mean of both ears) > 25 dB. Normal hearing = remaining participants.

^bParticipants with missing information about self-reported noise exposure (N = 167) were excluded.

Table 3. Prevalence ratios of tinnitus^a in relation to JEM-based occupational noise exposure among 14,945 participants in HUNT4 Hearing (2017–2019), Norway.

	Prevalence ratios of tinnitus^a, PR (95 % CI)
	Categorical JEM-based noise^b				Continuous JEM-based noise
	Moderately exposed		Highly exposed
	Model A^c	Model B^d	Model A^c	Model B^d	Model A^c	Model B^d
Total sample	0.95 (0.83–1.09)	0.96 (0.84–1.11)	0.88 (0.72–1.09)	0.91 (0.73–1.14)	0.98 (0.97–1.00)	0.99 (0.97, 1.01)
Stratified analyses^e
Normal hearing	0.92 (0.77–1.10)	0.96 (0.80–1.16)	0.86 (0.61–1.20)	0.93 (0.65–1.31)	0.97 (0.95–0.99)	0.98 (0.96, 1.01)
Elevated hearing thresholds	0.87 (0.72–1.06)	0.88 (0.71–1.08)	0.76 (0.58–0.98)	0.77 (0.59–1.02)	0.97 (0.95–1.00)	0.98 (0.96, 1.01)

Significant values in bold (p < 0.05).

^aTinnitus > 1 h daily.

^bCategorical JEM (job exposure matrix)-based exposure: low = no exposure ≥ 80 dB (reference group); high = minimum 5 years ≥ 85 dB; moderate = not fulfilling criteria for low or highly exposed.

^cPrevalence ratio, Poisson regression analysis adjusted for age and sex. Total sample and stratified by hearing status.

^dPrevalence ratio, Poisson regression analysis adjusted for age, sex, education, head injury, leisure noise, smoking, feeling nervous/uneasy and years of unemployment. Total sample and stratified by hearing status.

^eElevated hearing thresholds = thresholds at 3–6 kHz (mean of both ears) > 25 dB. Normal hearing = remaining participants.

Table 4. Prevalence ratios of tinnitus^a in relation to self-reported occupational noise exposure among 14,778 participants in HUNT4 Hearing (2017–2019), Norway.

	Prevalence ratios of tinnitus^a, PR (95 % CI)
	Moderately exposed		Highly exposed
	Model A^b	Model B^c	Model A^b	Model B^c
Total sample	1.38 (1.20–1.60)	1.34 (1.16–1.55)	1.47 (1.20–1.79)	1.41 (1.15–1.72)
Stratified analyses^d
Normal hearing	1.37 (1.13–1.66)	1.34 (1.10–1.62)	1.11 (0.79–1.55)	1.09 (0.78–1.53)
Elevated hearing thresholds	1.22 (0.99–1.50)	1.22 (0.99–1.50)	1.35 (1.06–1.71)	1.33 (1.04–1.70)

Significant values in bold (p < 0.05). Exposure categories, self-report: low = no prior exposure (reference group); high = >15 h/week ≥5 years; moderate = not fulfilling criteria for low or highly exposed.

^aTinnitus > 1 h daily.

^bPrevalence ratio, Poisson regression analysis adjusted for age and sex. Total sample and stratified by hearing status. Participants with missing on self-reported noise exposure (N = 167) were excluded from these analyses.

^cPrevalence ratio, Poisson regression analysis adjusted for age, sex, education, head injury, leisure noise, smoking, feeling nervous/uneasy and years of unemployment. Total sample and stratified by hearing status. Participants with missing on self-reported noise exposure (N = 167) were excluded from these analyses.

^dElevated hearing thresholds = thresholds at 3–6 kHz (mean of both ears) >25 dB. Normal hearing = remaining participants.

Data availability statement

The datasets generated and/or analysed during this study are not publicly available due to Norwegian legal restrictions and the current ethical approval for the study.