In the last few days, results of a recent US study were reported extensively in the press. It established that people with long-term exposure to loud noise at work or in leisure activities may be at increased risk of heart disease. Researchers found the strongest link in working-age people with high-frequency hearing loss, which is typically the result of chronic noise exposure to loud noise over time.
This is not new. Previous research had already linked noise exposure, especially in workplaces, to coronary heart disease, high blood pressure and other illnesses by looking at decibel levels in the person’s environment. This latest study concentrates on participants’ recollections about their work and leisure-time noise exposure. We agree that both are important considerations when assessing and controlling noise exposure in the workplace. Here we take another look at noise specifically and the many different ways it can affect our health and productivity.
Noise and the ear
The ear is extremely sensitive. It has three main sections – the outer ear, middle ear and inner ear. The sound pressure wave passes into and through the outer ear and hits the eardrum causing it to vibrate. The vibration causes the three auditory ossicles (malleus, incus and stapes) in the inner ear to move and transmit the sound to the fluid in the cochlea. The movements in the fluid are sensed there by hair cells. This is what allows us to differentiate between frequencies. Hair cells nearest to the middle ear respond to high frequency and those at the tip of the cochlea respond to lower frequencies. There are around 30,000 hair cells within the ear. When noise is too loud, it begins to kill hair cells in the inner ear. As the exposure time to loud noise increases, more and more hair cells are destroyed. There are plenty of videos to view on YouTube about how our hearing works.
Noise is a nuisance
Noise describes loud, sudden, harsh or irritating sounds. If it is not controlled correctly, it can lead to ear damage on a temporary (acute) or permanent (chronic) basis. We have listed below the three main temporary effects:
- Temporary threshold shift – caused by short excessive noise exposures such as firecrackers. Leads to mild deafness after the event which is reversible once the noise is removed.
- Tinnitus – a ringing or buzzing in the ears caused by an intense and sustained high noise level which can last for up to 24 hours even after the noise has stopped.
- Acute acoustic trauma – caused by a very loud bang such as an explosion. This is reversible unless the eardrum has been permanently damaged.
The three permanent hearing effects resulting from occupational noise are:
- Noise-induced hearing loss (NIHL) – affects the ability to hear speech clearly
- Permanent threshold shift – most marked at or above 4000 Hz frequency and a difficulty in hearing words that contain certain consonants e.g S, F, SH, CH, H, or soft C.
- Tinnitus – in its permanent form. This can develop without any warning.
Other health issues caused by noise
Noise is a nuisance but does not always result in hearing loss. It can make life difficult, unpleasant and restrictive through:
- Loss of concentration
- Tension and headaches
- High blood pressure
- Insomnia, tiredness and stress
- Social isolation
Action to prevent noise becoming a nuisance at work
Noise at work can be, and should be, controlled. As an employer, you should not disregard or underestimate the harm a noisy workplace can cause. In the UK and around the world, legislation exists and indeed specifies mandatory action levels at which the hearing of employees must be protected.
Here at Pulsar Instruments, we spend a lot time advising safety professionals about the legislation and how to prevent a company being sued for noise-induced hearing loss. We provide guidance on the different types of instrumentation available from us to measure noise correctly and how to apply any measurements to the current noise legislation. We will be happy to respond to any questions you may have on this subject – get in touch using our contact form.
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