AIMSS Race Driver Hearing Protection Study
AIMSS recently collaborated with the Perth based Curtin University of Technology, (School of Public Health), to conduct a pilot study into;
- In-car noise exposure for circuit race drivers; and,
- Relevant hearing protection evaluation
The study looked at race drivers participating across a range of racing categories, representing a typical major Australian racing event. The data gathering component of the study took place at Barbagello Raceway W.A, with data specifically captured from the following 6 categories;
- V8SC Dunlop Series
- Formula Ford
- V8 Utes
- W.A. Saloon Cars
- Touring Car Masters
In the first instance AIMSS developed a methodology that could be practically applied to the racing and race event environment, allowing Curtin to then focus on the application of data collation and analysis.
Over three days of the event data was gathered from 3 different drivers in 3 different classes each day, and 4 on Sunday, totaling 10 full data sets. This provided a good mix of in-cockpit noise environments, representing a good portion of vehicle styles that a CAMS competitor may experience in typical circuit competition.
In addition to better understanding the in-car noise environment a racing driver is exposed to, and the appropriate attenuation device to manage it, a very intentional outcome of this research was to highlight and reinforce the need for race drivers to take responsibility for the health of their hearing, specifically whilst competing.
The study methodology essentially comprised of three major initial components;
1. Using a Dosimeter, identifying and measuring accurately noise levels in the cockpit of the various racing car categories within 300mm of the drivers ear to best capture the drivers exposure, both in racing and practicing.
2. Gathering a snapshot of what styles and range of hearing protection is currently being used by race drivers in competition across a typical racing weekend comprising multiple racing categories. A pleasing 121 Drivers from the race event took the time to fill out and return questionnaires regarding age, hearing loss/hearing test status, and current noise attenuation devices used.
3. To provide a general guide for racing drivers (attached), 37 different hearing protection devices were evaluated and tabled to provide suitable hearing protection recommendations matched to measured noise levels, specific to the various racing categories monitored.
As a summary statement from the research, it is reasonable for any prudent race driver to assert that noise levels in all race vehicles, whilst competing or practicing are above what would be deemed acceptable thresholds without suitable hearing protection. In some instances significantly above those thresholds.
To reinforce this statement, across the 5 different styles of race vehicles (6 different racing categories), every driver monitored was exposed to a peak noise level of above 140dB(C)*, in at least one race on one of the days according to the data obtained. Additionally, all drivers exposure exceeded the standard of an LAeq,8h* of 85db(A)* at least once over the 3 days, and predominately in some classes on all days.
(* See attached Report for detailed information)
The graph below represents the average measurements as gathered at Barbagello Raceway, and identifies the ideal target band for acceptable noise exposure to drivers using hearing protection. As can be evidenced, wearing hearing protection for drivers during racing activity is needed to attenuate excessive noise that can cause hearing loss/damage.
Below: Average measurements over event and ideal attenuation target band for drivers
It was pleasing to see that from the 68% of the 121 drivers surveyed that used some form of in-car hearing protection, the majority chose custom moulded devices. More surprising however, as seen in the pie-chart below, was that 32% of the surveyed drivers wore no protection at all.
Below: Hearing Protection Devices Used – All Drivers Surveyed
Hearing protection device used by race category
As can be seen in the column graph below, the vast majority of those drivers wearing no in-car ear protection participated in the Saloon Car category, which, whilst not as profound as other categories, did exceed recommended standards. In this instance it could be reasonably assumed that education may be required where the incorrect perception may be that a saloon car derived from a more ‘production based’ platform, does not provide harmful levels of cockpit noise.
Note: The small sample sizes in Formula Ford and TCM on this graph are due to loss of data.
Commonly used examples of hearing protection…
Understanding Hearing Protection Attenuation Standards
A variety of methods exist to test hearing protection attenuation. The main methods as documented by Australian Standards are the SLC80 method and the class method. The SLC80 method of hearing protection indicates the difference between the measured C-weighted sound pressure level of the workplace noise outside the hearing protector and the A-weighted sound pressure level, attenuated by the hearing protector, under the hearing protector inside the ear canals.
Below: Class and corresponding Db(A) and SLC80 range
Below: This chart outlines the recommended class of hearing protection required to manage measured in-car noise to acceptable standards for the driver, for the respective categories studied.
Below: Various hearing protection brands recommended to category by class and SLC80 rating
Below: Various hearing protection brands NRR to SLC80 rating and class equivalent
The following devices have unattainable SLC80 ratings and have Noise Reduction Ratings (NRR) only, meeting American standards but not Australian standards. Due to this the NRR is converted to an estimated SLC80 range or class method it may correspond to.
For circuit racing and competition Drivers, AIMSS would consider exposure to noise in Motor Racing to start at potentially a very young age, and it would be prudent to ensure younger participants, including Karters, are not only aware of hearing protection, but form good habits early on, and for the duration of their career.
AIMSS has presented the findings from this research for the benefit of CAMS members who may find themselves exposed to in-car noise relevant to this research. However with the huge variety of vehicle/driver configurations including, engines, exhaust, intake, drivetrain, intake, seat position, helmet, and of course the actual racing environment to name but a few variables, AIMSS strongly recommends that competition drivers take responsibility for the health of their hearing by identifying the most suitable and effective hearing protection device for their particular circumstance – and to do so at the earliest possible point in their motor sport participation.
Click on button below to read a condensed version of the full study
AIMSS would like to thank Kareem Ahmed Magar (Researcher) Dr Janis Jansz (Snr Lecturer) and Dean Bertolatti (Associate Professor) of Curtin University of Technology, School of Public Health for their collaboration and co-operation with AIMSS as part of this study.
For his work on this pilot study, AIMSS would like to congratulate researcher Kareem Ahmed Magar on recently being presented with; ‘The Safety in Workplaces Award for the Curtin University best Master’s of Occupational Health and Safety research project completed in 2013.