NOISE AND HEARING LOSSES AND MEASURES TO BE TAKEN
The noise that we must emphasize is not only the problem of the workplace, but also the problem of the majority of people in today's life. The size of this problem and its negative effects are growing.
It is impossible to deny the words of Robert KOCH many years ago for the noise which is the main concern of the century. Gibi As with diseases like cholera and plague, the years we will fight noise are close ”. But humanity is still not struggling enough with this trouble.
Hearing loss, which can occur in every stage of life for many reasons, has been a problem throughout human history. Hearing loss can occur for many reasons. The most important of these reasons is the noisy work that people working in the industry are exposed to.
More effective and faster machines in the industry have caused the noise level to rise. It is estimated that the number of people with industrial hearing loss, which is not very common in SSK statistics annuals, exceeds 200,000.
Noise, which constitutes a very important health risk from an industrial point of view, is also an important health problem for general public health. It is seen that all values exceed the permissible values in the meli Noise Regulation değer, especially during long-term measurements in different districts of Istanbul.
Initially, all attention was focused on the effect of noise on the human ear, but over the last 40 years extracurricular effects have been taken into account (such as thoughtfulness, forgetfulness, psychological effects, speech impairment, reduced working power).
First of all, we should never forget that the treatment of hearing loss due to noise is medically impossible today.
In order to better understand the effect of noise in the ear, let us briefly explain the definition of noise, the structure of the ear and the hearing mechanism.
DEFINITION OF NOISE
In order to define the noise which affects the mental and physical structure of the human being negatively, it is useful to mention the physical qualities of the sound and hearing.
Sound: Gas, solid and liquid body molecules in the air pressure fluctuations in the ear is a feeling of the effect.
Noise: Generally defined as unwanted sound. It is a sound spectrum with a beautiful structure that can be described as unpleasant, unwanted, disturbing sound. Sound, on the other hand, is a physical phenomenon that is caused by fluctuations in the air pressure of a vibrating source and evokes a sense of hearing. As a physical concept, there is no difference between sound and noise.
Noise is an artificially generated, undesirable, quality and quantified noise. As can be understood from the definition, the notion of unwantedness shows that the noise may vary subjectively, that is, it may vary from person to person, and thus the effects on the psychological and neurovetitive system may be different in humans. The most important effect of noise, which does not differ significantly from person to person, is its effect on hearing.
After these two general definitions, when we look at how the definition of noise is defined in Article 3 of the convention signed at the 63rd Conference of the International Labor Organization (ILO), we see that the term ürültü noise ses includes all sounds that cause a hearing loss or cause health hazards or other hazards ”. It is important for us that this definition, which receives noise together with human health.
The deterioration of the quality of sound is the overlap of many sound waves with different frequencies. In other words, when we look at the frequency spectrum of noise, it is known that sounds occur at many frequencies. The deterioration of the quantity of sound is that, no matter how qualified and pleasant the sound is, its violence reaches a harmful value for the human body. For example, if we like the sound of a very nice music 90 dB (A) level will cause hearing loss. Of course, this effect of noise is the most easily visible effect. Psychological and neurogetative system effects may begin even at lower intensity sounds.
Decibel: The human ear is an organ that can respond to pressures of 0.0002-2000dyne / cm2. Decibel (db) in relative units is used in the evaluation of sound intensity to avoid unnecessary large numbers of studies.
Frequency: As the sound is a wave movement, every wave movement has a frequency in its sound. Roughly the number of vibrations per second of sound pressure.
Usually measured in Hertz (Hz). A normal adult person can hear sounds in the frequency range from 16 Hz to 20000 Hz. The ability to hear sounds at medium and high frequencies decreases with advancing age.
EAR STRUCTURE AND HEARING MECHANISM
Physically, sound is the result of mechanical vibrations of matter. This vibration is propagated by causing periodic changes in the density of the surrounding environment. The ear converts the energy carried by sound waves into neural vibrations to be perceived by the brain. The human ear is composed of three parts: outer, middle and inner ear. Each part has separate functions in the hearing event (Figure 1).
Fig.1- The structure of the ear; outer ear, middle ear (eardrum, hammer, anvil, stirrup) and inner ear.
The outer ear collects and directs the sound waves towards the middle ear, and as the sound waves enter the middle ear, they first strike the eardrum and vibrate the membrane.
With the help of hammer, anvil and stirrup bones in the middle ear, vibrations caused by sound waves are carried to the inner ear.
The inner ear is composed of a liquid-filled snail tube. This tube contains very fine sensitively sensitive strands and yarn cells as well as sensitized cells dispersed in the liquid. When the sound waves coming to the inner ear are carried to the hearing center of our brain with the help of these strands, we perceive the sounds (Picture.2).
Picture.2- Spreading sound in one ear. The cochlea transmits the sound that it receives from 35,000 sensitive hair cells within the cortical organ to the brain through 18,000 nerve fibers.
The sound is not only collected by the scoop of the ear, but is carried to the strands in the inner ear with the help of the skull bones just behind our auricle.
Sound waves are generated by the activation of air from mechanical events.
Sound waves enter the ear canal and vibrate the eardrum.
The vibrations pass through three ossicles (hammer, anvil, stirrup) connected to each other in the middle ear.
This action activates the fluid in the inner ear.
The moving fluid waves thousands of fluffy cells, causing vibrations to become neural stimuli.
The hearing nerves deliver these neural impulses to the brain.
The brain transforms these warnings into the sound (senses) we hear.
Healthy Ear: The following image (Figure 3), taken with an electron microscope, shows the image of the hair cells (cilia) on the surface of the snail (cohlea) in the inner ear. As a result of the sound, the movements of the hairs turn into electrical signals and reach the brain. This is how hearing works. In a healthy ear, the hairs are upright and dense as shown.
Image.3- Image of hair cells on snail surface in a healthy ear.
Damaged Ear: The image of the inner ear of a person with hearing loss as a result of noise, taken with an electron microscope (Figure 4). The hair cells are very thin, the existing ones are oblique and incapable.
Image.4- Image of hair cells on the surface of the snail in a damaged ear.
SOUND PHYSIOLOGY
Human ear vibration 16 Hz. and 20,000 Hz. Therefore, this kind of sound is called “hearing sound”. Sea waves, frost, earthquakes, wind sounds, such as 20 Hz. sounds below the "infrases" (infrases), the most recently used in the diagnosis and treatment of diseases, "above 20,000 Hz sounds" ultrasound "is called. Human voices are located at frequencies of approximately 250-500-1000-2000 Hz. Male voices are at lower frequencies (250-500 Hz) and female voices are at higher frequencies (1000-2000Hz).
In order to hear the sound, its intensity needs to reach a certain level. Moreover, the human ear does not show the same sensitivity to sound at all frequencies.
That is, the human ear has different thresholds of hearing at different frequencies.
At this point, we can see some examples of the noise levels we hear or experience in daily life.
Hearing Limit (Threshold) 0 dB
Recording Studio, Forest, whispering speech at 120 cm 0-20 dB
Bedroom 20-30 dB
Library, Quiet office, Living room 30-40 dB
General office, Conversation 40-60 dB
Working office (Typewriter, etc.) 60-70 dB
Average Traffic Noise, Noisy Restaurant, Printing House 70-90 dB
Pneumatic Hammer, Machine Tools, Automatic Drill, Textile Fab. 90-100 dB
Hydraulic Press, Pop Group, Circular saw, Air gun 100-120 dB
Jet engine, (Pain or Threshold Threshold) 130 dB
City alarm siren 140 dB
Rocket launcher 180 dB
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