True measurements of workplace noise for operators

Software designed to work with B and K's family of sound level meters can combine the noise measurements with a profile of a person's movements to simulate their personal noise exposure

Occupational health and safety is a major concern throughout industry.

Problems such as broken limbs, loss of an eye or persistent backache have to be dealt with and measures taken to minimise the risk of such things occurring in the workplace.

However, it comes as a surprise to many that loss of hearing caused by workplace noise is second only to the broad category "disorders of the locomotor system" on the list of occupational diseases.

Millions of people suffer from noise induced hearing loss (NIHL), resulting in reduced quality of life.

In addition, the costs of compensation and early retirement payments are immense.

Hearing conservation programmes are implemented in most countries and governed by international and national standards and legislation.

Such programmes involve an assessment of the noise problem followed by noise control and noise reduction measures.

Important aspects of these programmes are the management of data, reporting of progress and the retrieval of data, for example, if a claim is made.

Noise generated by a single machine affects all people in a working area and individual data records must be kept for each worker.

Data must be archived in accordance with legislative requirements and must be easily accessible in the event of a compensation claim.

However, companies running hearing conservation programmes do more than simply file data.

Reports are prepared for management, the authorities and the workforce.

With a large workforce, the amount of data involved is immense and it requires specially designed modern software to allow relevant information to be reviewed quickly and easily.

Bruel and Kjaer developed its 7825 Protector software specifically for use in hearing conservation programmes.

Unique in the industry, Protector is designed to work with B and K's family of sound level meters, noise dose meters and sound level analysers.

The package enables users to quickly download sample noise profiles for specific locations and even for each individual worker.

This data is then used to calculate noise exposure for people or positions under investigation according to HSE guidelines.

Even in situations where only workpoint noise measurements are available and workers move about, Protector can combine the noise measurements with a profile of each person's movements to simulate their personal noise exposure.

The essential issue in fighting noise induced hearing loss is the assessment of noise exposure.

Hearing loss can be immediate with high sound levels but, in general, the problem in industry is from constant exposure to noise day after day, year upon year.

Harmful noise levels do not always cause pain so there is frequently no reaction or complaint from the workforce.

Unfortunately, when a worker does realise that his/her hearing is impaired, it is often too late to do anything about it.

One tried and tested method for evaluating noise exposure for an individual worker is the use of a personal noise dose meter.

These are small, lightweight instruments worn throughout the working day.

The microphone is placed close to the ear, often attached to the collar.

The noise exposure of the worker can then be measured and is usually recorded directly as a percentage of the allowed daily exposure.

This method is indispensable when workers move from place to place with no fixed schedule.

Some dose meters, such as B and K's type 4442, accumulate the exposure of one day into a single result that is stored in the instrument for later downloading and analysis.

More advanced dose meters, such as B and K's type 4443, can also log the measurements and produce a statistical analysis of the noise levels allowing users to study when and where excessive noise levels occur and enabling appropriate preventive action.

In many cases where working points are fixed (e.g a punch press or pneumatic nailing machine) and individual work schedules are known, the noise exposure can be computed from the data gathered at the site using an integrating sound level meter such as B and K's 2239 or the 2238 MediatorT.

Noise levels are measured at each working point and assigned to each worker's schedule (e.g three hours at one task, four hours at another).

From this data, each worker's noise exposure can be calculated directly.

The 7825 Protector software does all the computation and bookkeeping and even allows the user to evaluate the effects of changing the work schedule or reducing noise levels at specific working points.

Although hearing conservation programmes may seem costly - users may have to buy new instruments and software, the programmes run for years and many people have to be monitored - the investment necessary to run a successful programme may be the best a company can make.

A hearing conservation program not only protects employees from hearing loss but also helps to protect employers from compensation claims.

With loss of hearing due to noise in the workplace being such a major concern for industry, the implementation of hearing conservation programmes is certain to become more widespread in future.

Instrumentation and software such as that described above will, thus, play an increasingly important role in protecting the hearing of workers throughout industry.

With over 55 years experience, Bruel and Kjaer is a world leading manufacturer and supplier of sound and vibration products for use in a wide range of applications including environmental noise measurements, building acoustics, vibration measurements and quality control for use in the automotive, aerospace and consumer industries as well as by local authorities.

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