The Difference in Protection Efficiency Between Earplugs and Earmuffs: An Investigation Performed at a Workplace

Abstract

The hearing thresholds of shipyard workers have been measured with a Békésy sweep audiometer. The number of employees at different workplaces is so large that it is possible to select groups of workers of specified ages who have been employed by the shipyard for many years. These workers have used either earplugs of earmuffs for 5--10 years and have also been working all the time in almost the same noise environment. Three ways of investigation have been used to observe differences in the hearing levels between 'plug-men' and 'muff-men'. All three show a greater hearing impairment for 'muff-men' than for 'plug-men'. Under certain conditions earplugs provide the most effective protection although the attenuation is higher for earmuffs than for earplugs.

Interventions to prevent occupational noise-induced hearing loss: A Cochrane systematic review

“…The intervention consisted of two types of information and the distribution of personal noise level indicators. In two studies the long-term effects of using earmuffs were compared to using earplugs (Erlandsson et al, 1980; Nilsson & Lindgren, 1980). In fifteen studies a hearing surveillance, hearing conservation, or hearing loss prevention program was evaluated as the intervention of interest.…”

“…In the meta-analysis, the OR of sustaining a STS for the muff-wearing workers versus the plug-wearing workers was estimated at 0.8 (95% CI 0.63 to 1.03) for those in high noise levels and at 2.65 (95% CI 0.40 to 17.52) for those in low noise levels (Erlandsson et al, 1980; Nilsson & Lindgren, 1980). The results from the low noise group were not homogenous.…”

Cochrane method for systematic review and meta-analysis of interventions to prevent occupational noise-induced hearing loss – abridged

“…However, studies lacked long-term follow-up, a control group, and in some cases the outcome was evaluated by an acoustical consultant or an employee at the firm where the intervention was evaluated and a conflict of interest was apparent (14 cases). 2016) (1) and Adera (1993) (21) CBA (24) CBA Shipyard workers, n = 40, 1 shipyard, Sweden HPD HL Long-term Gosztonyi (1975) (25) CBA Various occupations in 1 company, n = 142, USA HLPP HL Long-term Hager et al (1982) (26) CBA Various workers, n = 43, 1 company, USA HLPP HL Long-term Heyer et al (2011) (27) CBA Workers, n = 6483, 2 automotive plants, (33) CBA Army conscripts, n= 1234, Military, Sweden HLPP HL Short term Nilsson (1980) (34) CBA Ship builders, n = 231, Sweden, 1 shipyard HPD HL Long-term Pääkkönen et al (1998) (35) CBA Shooter, n=5, Military, Finland HPD NE Immediate Pääkkönen et al ( 2001) (36) CBA Air combat plane, n = 2, Military, Finland HPD NE Immediate Park and Casali (1991) instruction (37) RCT Various workers, n = 40, several companies, USA HPD HL Immediate…”

“…Caption: CBA = controlled before after study, ITS = interrupted time series analysis, RCT = randomised controlled trial, HL = hearing loss, NE = noise exposure, HPD = hearing protection device, HLPP = hearing loss prevention program; n = number Caption: Adera 1993: Forouzanfar et al (1) and Adera (21) , Adera 2000: Adera et al (11) ; Berg 2009: Berg et al (22) ; Brink 2002: Brink et al (23) ; Davis 2008: Davies et al (7) ; Erlandsson 1980: Erlandsson et al (24) , Gosztonyi 1975: Gosztonyi (25) ; Hager 1982: Hager et al (26) ; Heyer 2011: Heyer et al (27) ; Horie 2002: Horie (28) ; Huttunen 2011: Huttunen et al (29) ; Joy 2007: Joy & Middendorf (8) ; Lee-Feldstein 1993: Lee-Feldstein (30) ; Meyer 1933: Meyer & Wirth (31) ; Moshammer 2015: Moshammer et al (32) ; Muhr 2006: Muhr et al (13) ; Muhr 2016: Muhr et al (33) ; Nilsson 1980: Nilsson (34) ; Pääkkönen 1998: Pääkkönen et al (35) ; Pääkkönen 2001: Pääkkönen et al (36) ; Park 1991a instructions: Park & Casali (37) ; Park 1991b protection: Park & Casali (37) ; Pell 1973: Pell (10) ; Rabinowitz 2011: Rabinowitz et al (9) ; Reynolds 1990: Reynolds et al (38) ; Royster 1980: Royster (39) ; Salmani 2014: Salmani et al (40) ; Seixas 2011: Seixas et al (14) ; Simpson 1994: Simpson et al (41) ; (+) = low risk of bias; (-) = high risk of bias;…”

Comparative study of attenuation measurement of hearing protection devices by real ear attenuation at threshold method

“…The muffs and most ear plugs produced similar attenuation levels at high frequencies, although the muffs produced less attenuation at low frequencies. The study on the difference in protection efficiency between earplugs and earmuffs by Erlandsson et al, [6] shows a greater hearing impairment for 'muff-men' than for 'plug-men' . Under certain conditions earplugs provide the most effective protection although the attenuation is higher for ear muffs than for ear plugs.…”