What is noise and why is it so dangerous to our ear?

Noise is an unwanted sound that is harmful or disruptive to health and can lead to hearing loss.

Parameters used to describe sounds.

The main parameters describing noise are:

• Sound pressure - small changes in air pressure in which the sound is spread, expressed in Pascals [Pa]. Sounds heard by humans are 0.00002 Pa and sounds that cause ear pain have a pressure of over 60 Pa. Instead of acoustic pressure in the range of sounds perceived by humans, a logarithmic measure is used, which is the level of sound pressure expressed in decibels [dB], i.e. the level of sound intensity or noise level. The human ear best perceives sounds with frequencies from 1kHz to 4kHz. In order to properly assess the impact of noise on humans, the sound pressure levels are corrected in accordance with these frequency levels.
• Frequency - pitch, expressed in Hertz [Hz]. Sounds audible to humans are sounds with a frequency of 20 Hz to 20 kHz and in this range we are dealing with the so-called audible noise. Tones, correspondingly lower are infrasound, and correspondingly higher ones are ultrasounds.

The effects of noise

Exposure to noise can have a negative impact on the health and safety of workers:

• Hearing loss - caused by damage to the hair cells in the cochlea. After a certain group of cells die, a person ceases to hear only the sound frequencies for which the cells were responsible. But he still hears. Hearing loss occurs gradually and painlessly (except for noises exceeding 130dB where immediate hearing loss can occur).
• Increased risk of an accident - difficulties in communication between employees and limited audibility of alarm signals.
• Physiological effects - release of catecholamines and increase in blood pressure.
• Stress

The employer is responsible for reducing the impact of the noise source in the event of reaching or exceeding the permissible value, and if the noise is still exceeded, he must provide hearing protection.

Parameters characterizing noise in the work environment.

• maximum A sound level - this noise value must not be exceeded at any time,
• the level of noise exposure related to the 8-hour daily working time (or up to the working week), the human body can only absorb a certain dose of noise at a given time, which is directly proportional to the time and sound intensity. The level of exposure to noise depends on the so-called the A-equivalent sound level and is calculated over an 8-hour working day or working week (if the noise level on the individual days of the week is different). This allows for the estimation of the effects of noise, the level of which changes over time,
• peak C sound level (applies to impulse sounds) - this noise value must not be exceeded at any time.

Permissible noise values

• noise exposure level related to the 8-hour daily working time (or to the working week) - after exceeding the value of 80dB (A), the employer is obliged to provide the employee, at his request, with noise protection measures. After exceeding 85dB (A) it is obligatory.
• Maximum sound level A - when the value of 115dB (A) is exceeded, there is an obligation to use noise protection measures,
• Peak sound level C - after exceeding the value of 135dB (A), such an obligation also occurs.

The above-mentioned values ​​are valid, unless other specific regulations specify lower values.