Hearing loss is categorised into four common levels of sensory hearing impairment based on an algorithmic unit called ‘decibel’ which is used to measure the ratio between two values of a physical intensity. Using this measurement unit it is possible to measure the spectrum of hearing of an individual against a threshold of what the health industry deems as normal levels of hearing.
To establish the degree of hearing loss and to place it in the correct category, a hearing test called an audiogram is performed. The test plays sounds at different frequencies of high pitch, medium pitch and low pitch to establish the degree of hearing loss at different frequencies. Hearing loss should not be confused with deafness because unlike deafness certain frequencies can still be heard.
Hearing loss is linked to various causes, most notably age related and noise induced. In fact a research by the RNID (The Royal National Institute for Deaf People) in 2005 found that over 9 million UK residents display the telltale signs of hearing loss. By far the most common is the age related type known as presbyacusis which if found to a vary degree in individuals from the age of 40s, but extremely common in the over 70s.
To aid in our hearing, the inner ear contains many thousands of miniature hair cell structures visible only under the microscope. These tiny structures are paramount to our ability to hear as they capture sound in the form of vibrations and waves in the air. From the hair cells the information in passed to the brain using the hearing nerve where the information in processed to a language we can understand. As the body matures, the number of these hair cells will decline and their quality will diminish resulting in a growing difficulty to hear certain frequencies. Most commonly individuals experience an inability to hear high-pitched sounds such as “s” and “th” and in conversation people’s voices may sound mumbled or slurred.
The second biggest cause of hearing loss can be directly linked to work and lifestyle choices. Individuals often place their hearing in harms way, which can potentially lead to hearing loss. The human threshold for noise is 70dB, after which sound can become painful and damage to the same hair structures within the inner ear can occur. It is why in the UK, there is clear legislation in place when it comes to protecting workers in working conditions where sounds exceed 85dB. In our personal lives, there are no mandatory laws to adhere to and individuals are expected to avoid noisy situations.
In both cases of hearing loss, the damage to the tiny hair cells within the inner ear is the same and long lasting. These structures cannot regenerate so any ‘cure’ is in fact a treatment plan designed to reduce the impact of hearing loss on day-to-day life. Researches worldwide and in the UK are working on stem cell technology to help regrow the hair cells, though for now the most common treatment depends on a group of amplified devices in the form of hearing aids. These tiny devices reside inside or behind the ear and do wonders to capture external sounds instead of the inner ear hair cells. Hearing aids are available at no cost from the NHS, however in taking this route you will be subject to a short waiting list. An alternative is to take the private route in which high street and web vendors offer a wide range of hearing solutions at a cost. Another popular group are the ALDs which stands for ‘Assistive Listening Devices’ and it comprises of personal amplification devices from hard of hearing telephone to amplified doorbells.
The most suitable solution for treatment will be offered following a hearing test. The test will determine the level of hearing loss based on four categories:
- Mild Hearing Loss is defined as a loss of 20-39 dB
- Moderate Hearing Loss is defined as a loss of 40-69 dB
- Severe Hearing Loss is defined as a loss of 70-90 dB
- Profound Hearing Loss is defined as a loss of greater than 90 dB
Mild and moderate hearing loss can be managed using amplified aids, while severe and profound hearing loss will often include amplified aids in the form of cochlear implants as well as lip-reading and even sign language. If you are concerned about your hearing, you should book a hearing test (often free and never painful) or at least talk it over with your GP.
Information courtesy of Hearing Direct.
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