Daily noise exposure can lead to permanent hearing loss in nightclub bar employees

New research shows that nightclub bar employees could be exposed to noise levels almost four times over the legal limit. Aoife Kelly, a PhD researcher in Dublin Institute of Technology also found that nightclub managers showed little awareness of the relevant health and safety legislation and had not provided hearing tests for their employees or provided training in noise awareness. Her findings have been published in the International Journal of Noise & Health.

Aoife measured the typical noise exposure of two bar employees in each of nine venues in Leinster and found that their average daily noise exposure (L_EX,8h) was 92 dBA, almost four times more than the accepted legal limit. The employees worked an average of 20 hours per week and were on average 25 years old and working in the industry for 5 years.

She attached a calibrated logging dosimeter to the shirt collar of each of the bar employees who took part in the assessment and she placed a fixed position sound level meter (SLM) behind the bar closest to the dance-floor in each nightclub. Daily noise exposures ranged between 89 dBA and 97 dBA. The legal exposure limit value is 87dBA.

Noise exposure is calculated on a daily 8 hour basis. Exposure to noise in excess of 85 dBA over an 8 hour period per day can lead to permanent hearing loss over a number of years exposure. Due to the equal energy principle, a daily noise exposure (L_{EX, 8h}) of 92 dBA is equivalent to listening to a smoke alarm continuously for more than 32 hours.

The noise levels in the nightclubs rose by an average of 7 dBA between 11.30 and 1.00am - each 3 decibel increase is equivalent to doubling the sound pressure level. None of the venues exceeded the legal L_Cpeak values for noise and the frequency of the music was in the lower octave bands of 63 and 125 Hz. These noise level findings are comparable to other studies in the UK, America and Australia.

Since 2008 the nightclub sector has had to comply with stricter health and safety legislation to help protect employees from developing noise induced hearing loss (NIHL). There is a challenge for nightclubs to balance their legislative requirements, protect their employees and deliver the aural experience the patrons expect.

The nightclub managers in the venues she visited completed detailed questionnaires and Aoife also interviewed them about the relevant health and safety legislation that applied. Their awareness of the legal requirements was poor and a noise risk assessment had only previously been carried out in two of the venues. None of the nightclubs assessed provided hearing tests to employees or trained their staff about noise awareness.

According to the Noise regulations, hearing protection must be provided by employers and worn by employees when noise exposure exceeds 85 dBA. Two venues had provided hearing protection to their employees but only one venue actually made it mandatory that staff wear the hearing protection. By wearing the hearing protection the staff's noise exposure was reduced by 20 decibels. In the other venue, wearing hearing protection was at the discretion of the employees, who chose not wear it. Noise induced hearing loss is irreversible but 100% preventable. 

The Health & Safety Authority had not conducted inspections in any of the nine venues who participated in the research. In her article Kelly et al., highlighted a clear need for resourcing in the HSA to stimulate awareness and compliance to the noise legislation as risk if it is poorly communicated can lead to perceived risks being escalated to an unsubstantiated level.  

Aoife carried out her assessments with the full co-operation of the nightclubs and she aimed to support the nightclub managers to become more aware and compliant with the noise legislation by providing a free noise risk assessment for any nightclub that participated in the research. DIT would like to thank the nightclub industry for participating in this study, granting access to the nightclub employees and allowing Aoife to measure the sound levels in their venues.