In both cases the contributing factor that leads to reduced hearing is linked to the inner ear tiny hair cells that either die or diminish in quality. The inner ear contains up to 20000 microscopic hair-like cells that are tasked with capturing waves in the air across a wide spectrum of frequencies. Once these waves are captured the information is passed to the brain via the hearing nerve, where the information is made into tangible language that we simply categorise as ‘sound’.
In the case of age related hearing loss, the demise of the inner ear hair cells is natural and is likely to affect individuals from as early as their 40s, though more common in the over 60s. It is simply one of the challenges that growing older brings with it and individuals cannot hold back this natural process. In the case of noise induced hearing loss, the picture is completely different. The cause is directly linked to work and lifestyle choices that individuals actively take, often while well aware of the risks. It is widely believed that sounds exceeding 85dB can damage the inner ear hair cells and because these cannot regrow, the damage is permanent. For example, working a chain saw without hearing protection can expose the ear to 120db leading to possible inner ear hair damage (contributing factors: distance from the noise source and duration of exposure). While on the other hand, enjoying bird song will only expose the ear to 44dB well below the human pain threshold (70dB) and when damage may happen (85dB).
Treatment options for hearing loss to date revolve around managing the condition rather than curing it. In humans (as opposed to other species), the inner ear hair cells cannot regenerate so any treatment option aims to help manage the condition. However, it is worth noting that researchers are actively working on ways using stem cell technology to regenerate hair cells. Such treatment is many years away, though promising for the completely deaf. For now, the most widely effective treatment options rely on amplified devices to send sounds to the hair nerve. Common devices include digital hearing aids, hearing impaired telephones, personal alerting devices and recreational headphones for TV watching and music listening. Such aids are effective in the case of mild (defined as a loss of 20-39dB) to moderate (defined as a loss of 40-69dB) hearing loss. Some devices are even able to help in the case of severe hearing loss (defined as a loss of 70dB and beyond) but in the case of profound hearing loss individuals will have to use lip-reading and even sign language.
If you suspect that your hearing is impaired, you should consult with your doctor for an initial check or visit your local hearing centre for a hearing test. The test is pain free and can help determine long-term hearing loss causes from age related and noise induced reasons as well as less common reasons ranging from mild inner ear infection to prescribed medication.
Article by Joan McKechnie, BSc Hons Audiology & Speech Pathology.
Joan works for hearing company Hearing Direct brand of deaf and hard of hearing ALDs (assistive listening devices) and their accessories from batteries to alarms.