Keeping tabs on workplace noise.
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. Brüel & Kjær
developed its 7825 Protector software specifically for use
in hearing conservation programmes.
Unique in the industry, Protector is designed to work with B&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.
Assessing 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.
Measuring personal noise exposure
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&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&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.
Measuring noise levels at the working point
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&K's 2239 or the 2238 Mediator.
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.
For more information, please contact :-
Bruel & Kjaer, Bedford House, Rutherford, Close,
Stevenage, Hertfordshire, SG1 2ND. UK
Tel: +44(0) 1438 739000, Fax: +44(0) 1438 739099
Web site: www.bksv.com