| Study | Reason for exclusion |
|---|---|
| Aybek 2010 | Study design: one measurement per intervention, no before measurement, groups not comparable |
| Bealko 2009 | Study design: cross‐sectional design |
| Bockstael 2008 | Participants: HPD not tested on same participants |
| Bowes 1990 | Intervention and study design: only noise measurements and recommendations, no evaluation of measures taken |
| Brueck 2009 | Study design, intervention, outcome measurement: no work place intervention, laboratory tests and observations |
| Brühl 1994 | Study design: control group taken from database |
| Byrne 2011 | Participants: subjects were excluded if they were routinely exposed to occupational noise |
| Casali 2009 | Outcome: operational performance, no noise or hearing tests |
| Chou 2009 | Study design: cross‐sectional study, no pre‐intervention measurements |
| Franks 2000 | Participants: not a field study with workers |
| Giardino 1996 | Study design: not the same workers using different hearing protection |
| Golmohammadi 2010 | Study design: effect of intervention not evaluated |
| Griest 2008 | Participants and outcome: school‐age children, behaviour change, attitudes and knowledge |
| Groothoff 1999 | Study design: several case studies on noise reduction but no control group |
| Jelinic 2005 | Study design: case study only |
| Kardous 2003 | Study design: case study on noise reduction |
| Karlsmose 2001 | Participants: no noise‐exposed workers included |
| Kavraz 2009 | Study design and exposure: quasi‐experimental, attenuation not measured for the workers over a typical work day/situation (noise duration?, TWA?, high frequencies?, shift dose?) |
| Knothe 1999 | Study design: case study on noise reduction |
| Kotarbinska 2009 | Study design: immediate effect of HPD, but no control group and no comparison of 2 types of HPD on the same workers |
| Lempert 1983 | Study design: no control group, only one measurement before intervention |
| Lutz 2015 | study design: before – after comparison of HPDs on different persons |
| Mechfske 2002 | Participants: noise reduction for patients not for healthcare personnel |
| Merry 1992 | Participants: not a field study with workers |
| Monazzam 2011 | Study design: no measurement after the intervention |
| Mrena 2008 | Study design: two cross‐sectional studies |
| Murphy 2011 | Study design: laboratory results |
| Nair 2009 | Study design: no before measurement |
| Neitzel 2005 | Study design: not the same workers using different hearing protection |
| Neitzel 2008 | Study design and outcome measurement: one measurement before and after intervention, no control group, self reported HPD use |
| Niskanen 2001 | Study design: no control group, not an ITS |
| Oestenstad 2008 | Study design and exposure: retrospective study, control group built from database/recalculation of exposure data |
| Pearlman 2009 | Study design: experimental study in a laboratory |
| Pingle 2006 | Study design: case study only |
| Pääkkönen 2005 | Similar results as in Pääkkönen 1998 Study design: not the same workers using different hearing protection |
| Randolph 2008 | Study design, participants: no control group/ITS, no real workers/workplaces |
| Reeves 2009 | Study design: examples of before‐after measurements but not as time series or with some sort of control |
| Reynolds 1990b | Study design: not the same workers using hearing protection |
| Sataloff 2010 | Study design and participants: cross‐sectional study, no occupational noise exposure |
| Scannell 1998 | Study design: case study on technical noise reducing measures |
| Schaefer 1992 | Study design: case study on technical noise reducing measures |
| Smith 2006 | Study design: no ITS, no control group |
| Smith 2009 | Study design: no CBA measurements, no ITS |
| Smith 2011 | Study design: only one measurement before and one after intervention, no ITS, no control group |
| Stone 1971 | Study design: case study on technical noise reducing measures |
| Toivonen 2002 | Participants: not a field study with workers |
| Tsukada 2008 | Study design: no control group, no ITS |
| Walter 2009 | Study design: no control group, no ITS |
| Waugh 1990 | Outcome: no audiometric measurements, noise measurements before but not after the intervention |
| Williams 2004 | Participants: not a field study with workers |
| Wu 2009 | Study design: no data of controls before intervention |
CBA = controlled before and after HPD = hearing protection device ITS = interrupted time series TWA = time‐weighted average