The right ear protection for you
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Sound

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Definition of Sound

Sound is caused by vibrations from a sound source such as a machine, loudspeaker, or the human voice box. Sound is measured in Frequency (Hertz, Hz) and Sound pressure level (Decibel, dB).

Frequency

The most common sounds, like that of human speech (800-4000Hz), are found in the High and Middle frequency range. Low frequency sounds (below 500Hz) are usually generated by large engines, ventilation systems, etc.

The human ear can hear sounds in a range between 20 and 20 000 Hz. As we grow older, the ageing process itself, or exposure to high noise levels, causes a decline in our hearing, making it harder to identify high frequency sounds. 

Sound pressure

The lowest sound pressure level distinguishable by the human ear is 0 dB, and anything above 130 dB is likely to cause pain. 

Noise

What we call “noise”, is usually described as sounds we experience as unpleasant or disturbing. High level of noise is hazardous to your hearing. Noise can also lead to stress symptoms, discomfort, pain, and increased risk for heart disease. Harmful noise is everywhere. Loud music, a rock concert, motorsports, target practice or hunting, even mowing the lawn – it could all damage your hearing. These noises are often considered harmless, but they represent significant risk, and call for protection. All noises add to your daily quota of exposure, therefore it is important to wear proper hearing protection at all times.

Noise & Risk

When estimating the risk of hearing damage there are three important factors to consider; exposure time, frequency (Hz) and sound pressure (dB). The exposure time is measured during 8 hours, to simulate a standard work environment. A filter (dB A) is used, taking into consideration the normal tolerance curve of the human ear and giving a good estimation of the risk level. 

High frequency noise is the most damaging to your hearing, and should therefore be your primary concern.

Low frequency noise is usually less damaging, but can be dangerous because it masks human speech, alarm signals and it can cause symptoms like dizziness and nausea.

Some low frequencies are difficult to block out even with proper hearing protection, because it can transmit directly into the inner ear. 

The European Union has established a legal limit of 80 dB (A) over an 8 hours workday. Beyond this limit, protective measures must be taken. As the noise levels increase, the length of time you can safely stay in the environment, is reduced.

As an example: 8 hour exposure to 80 dB (A) is equivalent to only 4 hours in a level of 83 dB (A). An increase of 3 dB (A) means you must reduce your time in the environment, by 50 percent if unprotected. The same consideration applies, if you are exposed to two similar sound sources. Two machines, both emitting 80 dB (A) of noise, equals a total of 83 dB.

In addition to harmful noise of the steady and longer term kind, peak noises can be equally dangerous. Peak noises are typically those from firearms, hammers, nails guns and other air tools. Since our brain needs approximately 0,3 seconds to judge the magnitude and level of an incoming sound, peaks shorter than this can be very dangerous to your hearing. In fact, these peak noises could cause irrevocable damage to the inner ear in one single occurrence. Peak noises are measured with a “C”-filter (dB C).

Harmful Noise Levels

Origins and Noise Profile

Electrical Machines  90-110 dB (A), High Frequency
Wood cutter  90-110 dB (A), High Frequency
Airport 100-140 dB (A), High Frequency
Gunshot 140-180 dB (C), Peak, High Frequency
Chain saw  90 -110 DB (A), Middle to High Frequency
Ventilation fan  90-110 dB (A), Low Frequency
Diesel engine  90-120 dB (A), Low Frequency