Occupational noise exposure, noise annoyance, hearing-related symptoms, and emotional exhaustion - a participatory-based intervention study in preschool and obstetrics care

Figures & data

Figure 1. Timeline of the study phases, the intervention activities, and the data collection. The control workplaces participated only in the data collection (dark grey), while the intervention workplaces participated in all the intervention activities and the data collection.

Table 1. The selected and prioritized context-specific intervention contents implemented in the obstetrics care and the preschool setting.

Type of intervention	Obstetrics care setting	Preschool setting
Physical environment and hearing protection devices	Renovation and new floorplan: one big office was rebuilt into a breakroom, three new smaller offices and one “silent” office with sound-absorbing screens and ceiling absorbents. A “quiet corner” with recliners and dampening earmuffs, and no acoustic alarms in the new breakroom. Sound absorbing curtains in the new conference room (old breakroom). Using microphones during larger meetings/lectures. Lowering the levels on acoustic alarms on medical equipment. Ventilation system check. Soft calm music was played in the corridors. Green plants added to the corridors. Hearing protection device routines and availability in each team office and in delivery rooms, reminding each other to use them whenever loud screams from mothers giving birth occurred.	Installation of additional sound-absorbing wall panels and screens. Carpets and curtains to dampen sound and create “rooms within rooms”. Dampening cloth on shelves and in boxes for toys. Moved a TV that disturbed another department. A small bell used by both children and staff to indicate to others when the sound level is perceived as too high. Hearing protection device routines and availability.
Organizational and psychosocial	New routines during shift change to avoid large gatherings in the office areas. Easier access to the new breakroom located in the middle of the department. Own voice use, not shouting, asking others to speak quieter. Encouraging mothers if necessary to scream into oxygen mask during labor. Workplace meeting discussions and reflections about sound environment and work environment.	Awareness of sound and noise, when for example buying new toys. Awareness was also increased for the kitchen staff. New group composition at lunch. Fewer children in hallway and dividing the children into small groups indoors. Own voice use, not shouting, staff making a good example for children. Discussing work responsibilities and how to support each other. Workplace meeting discussions and reflections about sound environment and work environment.

Table 2. Baseline values for the outcome variables with categories or scale as analyzed, shown as valid column percentages (%*), or mean and standard deviation (SD), within the obstetrics setting and the preschool setting, separating the intervention workplace from the controls.

Outcome (variable type)	Response alternatives in survey and variable categories	Obstetrics care setting				Preschool setting
		Control (n = 66)		Intervention (n = 50)		Control (n = 28)		Intervention (n = 20)
		Mean (SD)	n (%*)	Mean (SD)	n (%*)	Mean (SD)	n (%*)	Mean (SD)	n (%*)
Hearing loss (binary)	No/Don’t know		55 (83)		40 (82)		23 (85)		17 (89)
	Yes (defining the outcome)		11 (17)		9 (18)		4 (15)		2 (11)
Tinnitus (ordinal)	No/No but have had		51 (77)		34 (69)		22 (79)		10 (50)
	A few times each month		6 (9)		6 (12)		2 (7)		5 (25)
	Sometime every week		3 (5)		2 (4)		3 (11)		1 (5)
	Several times each week		1 (2)		3 (6)		0 (0)		0 (0)
	Every day		5 (8)		4 (8)		1 (4)		4 (20)
Sound-induced auditory fatigue (ordinal)	No/No but have had		31 (47)		16 (32)		9 (32)		2 (10)
	A few times each month		17 (26)		12 (24)		7 (25)		4 (20)
	Sometime every week		8 (12)		7 (14)		7 (25)		5 (25)
	Several times each week		7 (11)		9 (18)		3 (11)		7 (35)
	Every day		3 (5)		6 (12)		2 (7)		2 (10)
Difficulty perceiving speech at work (binary)	No		47 (71)		23 (47)		15 (54)		8 (40)
	Yes (defining the outcome)		19 (29)		26 (53)		13 (46)		12 (60)
Hyperacusis (ordinal)	No/No but have had		45 (70)		22 (46)		12 (43)		6 (32)
	A few times each month		8 (13)		6 (13)		10 (36)		4 (21)
	Sometime every week		5 (8)		8 (17)		5 (18)		3 (16)
	Several times each week		4 (6)		9 (19)		0 (0)		3 (16)
	Every day		2 (3)		3 (6)		1 (4)		3 (16)
Noise annoyance (ordinal)	Not at all/somewhat annoyed		41 (62)		16 (32)		13 (46)		4 (21)
	Rather annoyed		21 (32)		21 (42)		8 (29)		8 (42)
	Very/extremely annoyed		4 (6)		13 (26)		7 (25)		7 (37)
Emotional exhaustion (scale)	Low indicates less emotional exhaustion, min-max: 1-6	2.80 (1.12)		3.26 (1.13)		3.00 (1.06)		3.67 (1.18)

* Valid column percentages exclude internal missing on specific outcomes.

Figure 2. Participant flow diagram detailing number of personnel enrolled, lost to follow-up, responding at each timepoint, and the final study sample included in the analysis.

Figure 3. Descriptive data of the individual change in the outcomes as valid percentages reporting improvement (green), worsening (orange) or remaining unchanged (grey) from baseline to follow up (merging results from t1 and t2) within the intervention group (I) and control group (C) respectively, in the obstetrics care setting (left) and in the preschool setting (right).

Table 3. Generalized estimating equation (GEE) analyzing the effect of intervention by comparing outcomes at follow-up in the intervention versus the control group in the obstetrics and the preschool setting respectively (control group as reference).

Outcome^§ (variable type)	Model	Obstetrics care setting				Preschool setting
		β	OR	95% CI	p-value	β	OR	95% CI	p-value
Hearing loss (binary)^a	Crude	0.799	2.22	0.65–7.63	0.204	NA*
	Adjusted	0.855	2.35	0.58–9.54	0.232	NA*
Tinnitus (ordinal)^a	Crude	0.167	1.18	0.58–2.40	0.642	−0.180	0.84	0.36–1.95	0.677
	Adjusted	0.071	1.07	0.37–3.11	0.895	−0.150	0.86	0.26–2.83	0.805
Difficulty perceiving speech at work (binary)^a	Crude	0.462	1.59	0.74–3.41	0.236	1.042	2.83	0.66–12.12	0.160
	Adjusted	−0.110	0.90	0.37–2.17	0.808	NA*
Hyperacusis (ordinal)^a	Crude	−0.116	0.89	0.54–1.48	0.653	0.799	2.22	1.24–3.99	0.007
	Adjusted	−0.517	0.60	0.34–1.06	0.079	0.933	2.54	1.23–5.24	<0.012
Sound-induced auditory fatigue (ordinal)^a	Crude	0.215	1.24	0.78–1.96	0.360	0.828	2.29	1.09–4.80	0.029
	Adjusted	0.033	1.03	0.64–1.68	0.894	1.852	6.37	2.51–16.18	<0.001
Noise annoyance (ordinal)^b	Crude	0.837	2.31	1.16–4.60	0.017	0.916	2.50	0.79–7.88	0.117
	Adjusted	0.838	2.31	1.11–4.80	0.024	1.489	4.43	1.34–14.72	0.015
Emotional exhaustion (scale)^c	Crude	0.226	1.25	0.95–1.65	0.107	0.639	1.89	1.35–2.67	<0.001
	Adjusted	0.114	1.12	0.85–1.48	0.417	Crude model is the final model

^§Definitions of outcome variable categories for binary outcomes and levels of ordinal outcomes are given in Table 2, second column from the left.

^aCrude models includes the baseline outcomes. Adjusted models in obstetrics were adjusted for: Age; Noise exposure at work; Percentage of full-time work; Noise annoyance; Disturbing, distracting, attention demanding sounds; Influence on resources; Time for reflecting about work; and Support from manager, in addition to baseline outcome. Adjusted models in preschool were adjusted for: Age; Noise exposure at work; Percentage of full-time work; and Time for reflecting about work, in addition to baseline outcome.

^bCrude models includes the baseline outcome. Adjusted model in obstetrics were adjusted for: Age and Noise exposure, in addition to baseline outcome. Adjusted model in preschool were adjusted for: Age; Noise exposure at work; Hearing protection at work; Disturbing, distracting, attention demanding sounds; Influence on resources; and Putting oneself aside, in addition to baseline outcome.

^cCrude models includes the baseline outcome. Adjusted model in obstetrics were adjusted for: Noise annoyance; General health; Division of household work and Recovery after work, in addition to baseline outcome. Crude model was the final model in preschool.

*Maximum likelihood estimates not available (NA) due to quasi-complete separation (separation means that the predictor, in this case intervention group, is associated with only one outcome value).

Figure 4. Boxplots of daily A-weighted equivalent sound levels (dB LAeq) from dosimeter measurements in the obstetrics care (left) and in the preschools (right).

Table 4. Descriptive data and analysis of average sound levels within each group over timepoints and between control and intervention group at each timepoint.

Setting	Timepoint	Group	n	Measurement time (hh:mm)			Daily equivalent sound levels (dB LAeq)				Maximum sound levels (dB LAFmax)
				Mean	Min	Max	Mean	SD	Min	Max	Mean	SD	Min	Max
Obstetrics care setting
	Baseline	Control	168	06:46	02:18	09:58	70.1	3.5	55.5	78.4	103.5	4.9	91.9	120.1
		Intervention	49	05:51	02:10	10:00	70.0	4.6	56.7	77.8	104.5	7.0	88.4	119.9
	Follow-up 1	Control	116	07:03	02:22	09:45	70.5	4.8	49.8	79.4	104.4	5.8	86.3	117.4
		Intervention	47	06:52	02:30	10:05	71.0	2.9	63.7	80.0	104.0	5.1	95.8	118.0
	Follow-up 2	Control	134	07:15	02:40	10:00	71.0	3.4	61.4	80.2	104.7	5.2	92.0	124.7
		Intervention	57	07:12	02:45	14:40	71.3	3.0	65.8	77.8	104.8	5.1	93.7	117.2
Preschool setting
	Baseline	Control	85	05:39	02:06	09:34	75.8	2.8	69.4	82.5	106.6	5.1	95.8	125.3
		Intervention	49	05:43	02:12	09:59	75.5	2.6	68.6	80.5	106.6	5.1	95.8	125.3
	Follow-up 1	Control	73	05:32	02:00	08:56	76.0	3.0	68.0	84.8	107.5	5.1	96.6	119.9
		Intervention	41	05:39	02:35	09:28	76.1	2.7	69.6	80.7	106.8	3.9	98.6	115.0
	Follow-up 2	Control	62	05:38	02:09	09:00	76.6	2.6	72.0	83.7	106.7	3.8	98.6	115.4
		Intervention	32	05:28	02:09	08:05	77.5*	2.5	73.1	83.9	108.0	4.4	99.6	119.4

*Significantly different mean sound level at follow-up 2 compared to baseline in the preschool intervention group.

Figure 5. Descriptive responses of perceived changes in the work environment within the intervention groups, showing improvement (green), worsening (orange) or remaining unchanged (grey) from baseline (t0) to the first follow-up (t1), and between the two follow-ups (t1 and t2) in the obstetrics care setting (left) and in the preschool setting (right).

Data availability statement

The participants of this study did not give consent for data to be shared. However, anonymised data is available upon reasonable request and providing approval from an ethical review board.