«Some facts on sound and noise
Leakage detection is for many companies primarily an economic issue. It is however closely linked to overall effectiveness and environment of the workplace as it contributes a great deal to the reduction of the workplace noise level. It is important to understand how sound affects us physically and our work.
Irritating noise in the workplace decreases the workplace capacity and performance. Generally speaking, irritation increases in direct proportion to the volume of the noise. Noise containing distinct, high pitched tones are particularly disturbing.
Noise is said to be masking when it prevents the ear from interpreting other sound signals, e.g. conversation and warning signals. Masking noise can therefore increase the risk of accidents in the workplace.
The primary physical effect of noise on humans is damage to the inner ear. The ear may be damaged acutely by extremely intensive noise such as a rifle shot, or successively by continuous exposure to for instance industrial noise.
Other physical effects are elevated blood pressure, an accelerated rate of breathing and increased production of gastric juices. Blood circulation, sleep and digestion suffer. This may lead to headache, nausea, muscular tension, mental and physical fatigue which in turn, can result in inattentiveness.
«What characterizes impaired hearing ?
A common but erroneous conception is that people become accustomed to noise. A positive attitude towards a source of noise does reduce some of the body's physical reactions but damage to the ear is inevitable. Certain hair cells are, in a sense, exhausted and paralyzed. What a person experiences as "getting used to" a noise is actually an impairment of the ability to perceive those frequencies where the noise is strongest. The "accustomed" person may even be insensitive to all frequencies that comprise the noise.
As has previously been mentioned, sound is interpreted when waves of pressure affect the cochlea in the inner ear. The membrane in the cochlea vibrates and affects the sensory hairs, which are bent for precisely the frequency that corresponds to that of the sound wave. Extreme stimulation of the same hair cells for a prolonged period of time disrupts the cell's metabolism, putting them temporarily out of order. One becomes hard of hearing. If the cells are permitted to "rest" a while after exposure to noise that is neither too extreme nor too prolonged, the cells recuperate and function is restored. If this stress occurs day after day and the hair cells do not have time to return to normal between exposures, the cell's blood supply and metabolism permanently change so that they can no longer function.
The frightening thing about hearing loss is that it, in its initial stages, goes unnoticed. The higher the frequencies that lie above the range of speech disappear first. One no longer hears the chirping of birds and the song of crickets. Eventually, the range of speech is affected as well. Consonants vanish first, then the vowels. The effect can come surprisingly quickly and be devastating.
«The effect of noise on humans
After sight, the sense generally considered as the second most important is the sense of hearing. It is primarily through speech and hearing that we communicate with one another. Hearing is also our most sensitive and important warning mechanism. It receives impressions from every direction and is open for impulses when a person is awake as well as asleep.
Modern society has created an environment in which the ear is the sensory organ most frequently and most easily is damaged. The human ear is not designed to endure or exclude much of the sound and noise that exist in the industrial society today. Therefore, hearing can be seriously impaired by loud and repetitive noise.
Loss of hearing can result in a person being partially or completely isolated from his surroundings. Such a loss can never be restored.
In the past, a noisy machine was a symbol of strength, power and wealth. People accustomed themselves to the noise i.e. they accepted it as the noisy machine meant income and existence.
The fact that those exposed to the noise became hard of hearing or practically deaf was considered a natural part of the occupation.
Today we no longer need to accept this rationalization. There are possibilities to reduce or eliminate noise, both in the workplace and in our private lives. It is simply a matter of making people aware of the dangers and the possibilities so that we can take action against noise. Many experts and researchers view noise pollution as one of the major environmental problems.
70 - 80 % of all hearing loss within the manufacturing industry today is associated with compressed air noise.