Noise-related hearing loss is one of the most common occupational health concerns anywhere in the world. Processing and manufacturing industry sites are invariably noisy, but employers have a duty of care to protect their workers from exposure to hazardous noise. What are the dangers and what steps should businesses take to protect their workers’ health, and their own reputations and legal positions? Arne Berndt, owner / adviser at SoundPLAN GmbH and SoundPLAN International LLC – a market leader in sound and air pollution mapping software – explains the steps to properly planning and mitigating noise emissions.

Workplace noise

Exposure to a noise level of above 85 decibels (dB) – that’s about the volume of city traffic from inside a car – puts people at risk of hearing loss. The risk then increases with the magnitude, exposure time and the frequency of the noise. Higher frequencies do more damage. Industrial noise can cause considerable health issues for workers; hearing loss makes up between 30% and 40% of occupation-related illnesses.

Alongside the human cost, there is also the potential for litigation against a business which does not act to protect its workers.

Noise in industrial situations comes from a variety of sources and can vary widely in power, frequency and directivity. The characteristics of the emitted noise of plant vary between irregularly distributed noise impulses and almost continuous noise levels.

Noise contour lines

Industrial noise cannot be categorised easily as there are often multiple sources and every situation is different. This makes evaluation and mitigation much more difficult compared to singular noise sources, such as traffic.

When there is a danger of hazardous noise it is necessary to find and document the areas where the 85dB level is exceeded. This is known as the ‘noise contour line’ and workers must wear hearing protection within it. If the noise contour line is not clearly marked companies can be fined. It must be readily apparent to workers where hearing protection is necessary, using appropriate signs and instructions. The noise contour line must be enforced wherever the noise exceeds 85dB, both inside and outside buildings.

In noisy environments (that may be close to, or above, 85dB) it is recommended that businesses invest in a noise study which will define the areas where hearing protection is needed. Alternatively workers can measure their daily noise exposure using a dosimeter. A well-studied and documented noise policy is more economical than paying for lawsuits from workers with hearing problems and compensating for disability because of tinnitus and hearing loss.

Loss of hearing and more

Loss of hearing has a significant impact on an individual as subsequent sound levels need to be high enough – and there must be a large variation between the levels of what people are trying to listen to and any background noise – if they are to hear anything. And it doesn’t only affect the person who has lost their hearing, but also those around them. People who suffer hearing loss often undergo social isolation, because they can no longer communicate in the way they always had before.

A further detriment is the risk that people with hearing loss cannot localise a noise source or cannot hear it at all. This can put them in danger in urban traffic or when fire alarms are activated.

Along with hearing loss, high levels of noise can affect workers in other ways, including disturbed sleep and cardiovascular disease.

Psychological impact

Hazardous noise can have a psychological impact on employees’ ability to work and concentrate and on their well-being. The impact includes disturbed communications, reduced reactions and a reduction of the psychological well-being (resulting in nervousness).

Workplace interaction

High noise levels can lead to considerable social problems. People are not able to interact normally in workplaces where undisturbed communication is not possible – either because of the noise itself or because they are wearing ear protectors – and can become isolated. This can lead to people becoming more aggressive and being less willing to help others as sociability is reduced.

Noise mitigation features can also have the unintended consequence of making it hard for workers to hear announcements or emergency alarms. To counter this, loudspeakers around a plant must be at least 10 dB above the ambient noise. There are also stringent rules for verbal messages. The implications of these requirements can be studied with a noise map.

Mapping noise

A noise map is created using simulation software to compile a model from data representing the infrastructure and the buildings involved. Noise maps can often be created using existing data sources, but each noise map is unique according to project size, geography, objective.

The noise levels in the simulation can be measured or calculated, and theoretical noise reduction measures can be tried and evaluated. This is a vast improvement on noise control engineers measuring actual noise levels and then using their best judgment to control it. When you measure, rather than simulate, noise there is only one result and it is not possible to assess individual sources or volume of noise from those different sources. Simulations offer the added benefit that you don’t have to wait for the noise to be made before you can measure and react to it. Instead you can plan for different scenarios prior to building or purchasing noisy equipment.

SoundPLAN has been a market leader in noise and air pollution mapping for over 25 years and it now has over 5,000 users, in more than 60 countries, including governments, consultants and researchers. Its versatile software is used by engineers responsible for developing and testing noise and air pollution reduction strategies for industry, rail and road projects around the globe. This may be for land use, air purity planning, environmental impact studies or public enquiries.

SoundPLAN allows users to comprehensively investigate and calculate noise and air pollution. It is fast, meets all major international standards and provides users with an accurate calculation package with superb graphics supporting all levels of customer presentation. It’s available in English, European and Asian languages, and our worldwide distribution means expert local support.

Defending workers

A noise map is a key step towards making the working environment safer. It allows you to assess the areas where you need to introduce controls to defend workers against noise. Reducing noise by just a few decibels can mean the risk of hearing loss and its many consequences is lessened dramatically; just a 3dB decrease means the sound energy is halved. The most common way to help protect workers’ hearing is to adapt or replace noisy equipment or the environment around it. Using low noise and well maintained equipment or placing a barrier between the worker and noise source are relatively simple steps, but they can have a huge impact on people’s lives.

Whether planning a new processing or manufacturing facility, or looking to improve an existing one, noise simulation software identifies problem areas and means workers can be protected from the dangers of hazardous noise.

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