More about hearing protection
What is sound?
Sound is mechanical waves where an oscillating pressure is transmitted through a material, liquid or gas.
Sound is defined in terms of frequency and intensity.
Frequency is the number of sound waves per second. Measured in Hertz (Hz)
The intensity is the pressure from the sound wave which represents the sound volume. Measured in Decibels (dB)
What is noise?
Noise is an unwanted sound.
According to a more complete definition, noise is for the individual and the environment an unpleasant and annoying sound that burdens or harms the organism physically or mentally.
A-weighted sound pressure level,
Weighted average of the sound pressure level within the audible frequency range measured with weighting filter A according to standard SS-EN 61672-1.
Also designated as sound level and specified in the unit dB(A).
Weighting filter A emulates the shape of the hearing threshold curve and is used to assess e.g. the risk of hearing damage.
C-weighted sound pressure level,
Weighted average of the sound pressure level within the audible frequency range measured with weighting filter C.
Also designated as sound level and specified in the unit dB(C).
Weighing filter C is used during the measurement of high impulse sound, i.e. sound with a duration shorter than 1 second. Also used in conjunction with weighting filter A when applying the HML method.
Daily noise exposure level, 8 hour workday.
Corresponding A-weighted sound pressure level normalized to an eight-hour workday. Includes all noise at the workplace, including impulsive noise.
Exposure limits according to the European Parliament’s and Council’s Directive 2003/10/EC
Lower exposure action values: 80 dB(A)/135 dB(C)
The employee must have access to hearing protection if noise exposure is equal to or exceeds any of the lower exposure action values.
Upper exposure action values: 85 dB(A)/137 dB(C)
Hearing protection must be used if noise exposure is equal to or exceeds any of the
upper exposure action values.
Exposure limit values: 87 dB(A)/140 dB(C)
Under no circumstances shall exposure of the employee exceed the exposure limit value. When working in environments with noise exposure above the exposure limit value hearing protection must be chosen so that the exposure limit value is reduced to the correct level.
NOTE! National deviations from the directive can occur.
It is important to use the protection all the time!
We can only tolerate a certain amount of noise per day before we risk permanent hearing damage. Factors that have an effect are the noise intensity and the time we spend in the noisy environment. For example, we are affected as much by 15 minutes at 100 dB(A) as 8 hours at 85 dB(A).
It is therefore important that the protection is worn at all times when in a noisy environment. Even short periods of “forgetfulness” during the day can significantly affect the expected level of protection.
Comfortable hearing protection with well-adapted attenuation to the environment you spend time in is a good starting point in order to preserve your hearing.
Remember that it is not just in the workplace that your hearing may be affected by noise. In everyday life we are constantly exposed to different sources of noise, these must also be included in the total amount of noise we are exposed to.