What are the Health Effects of Noise in relation to ill health?
Health Effects of Noise.
Moving on from the previous artice on Health Effects of Noise, it would probably be helpful to discuss the effects of Ill Health caused by noise in the workplace.
There are 3-distinct section to the human ear starting with the external ear (outer ear), the middle ear and the internal ear.
Hearing is based upon sound pressure waves being captured and funnelled by the outer ear down towards the middle ear. The pressure waves then strike the drum which is positioned approximately 25mm inside the head.
Set inside the middle ear is a delicate array of 3 small bones which transfer the vibration from the drum to the inner ear (or cochlea).
The cochlea contains a fluid that in turn creates movement in a membrane causing connected hair cells to bend.
The bending of these hair cells create a tiny electrical impulse which is transmitted to the brain along the auditory nerve which the brain then scrambles into the sensation we know as sound.
There are about 30,000 or so of these hair cells, and damage to them causes irreversible hearing loss.
Ill Health Effects of Noise
Ear damage can have two classifications. Acute effects and Chronic effects.
Acute damage can be classed as temporary where some sort of regain will occur, while chronic is generally classed as irreversible.
In addition, there are 3 classifications of both acute and chronic effects.
Temporary threshold shift.
This can be caused by short excessive exposure to noise and creates a disturbance within the inner ear by reducing the impulses sent to the brain. This results in a slight deafness, but is reversed when the noise subsides.
Acute acoustic trauma.
This can be caused by extreme sudden noises such as gunshot or explosion. It affects the ear drum and tiny bones in the inner ear, and again usually reverses itself after a period of time. (Although sudden loud noises can also cause permanent damage).
Usually caused by an intense noise over a period of time over stimulating the tiny hair cells created a perceived ringing noise in the ear. Often it subsides over 24 hours, but it can become a lifelong debilitating condition.
There are also 3 classifications of chronic effects of hearing loss.
Permanent threshold shift.
This condition is in response to the permanently unprotected or insufficiently protected loud sustained noise levels. The damage created is the irreversible reduction in nerve impulses sent to the brain which leads to the inability to hear at certain frequency levels, typically 4000hz.
Noise Induced hearing loss.
Although not total deafness, the ability to hear clearly is significantly reduced due to irreversible damage to the hair cells within the cochlear.
The same as the acute Tinnitus but permanent and very unpleasant, often leading to mental health instability and conditions such as depression or even suicide.
It’s also important to remember that repeated uncontrolled exposure can lead to gradual hearing loss that often goes unnoticed into older age. This is often classified as Presbycusis, or deafness in old age which could have been completely avoidable if appropriate ear protection had been worn at an earlier stage, or sufficient measures were put in place by the employer.