Hearing 

Hearing is a complex process. Sound waves are transmitted through the external auditory canal to the eardrum, which vibrates. The ossicles - hammer, anvil, stirrup - in the middle ear amplify the vibrations and transmit them to the cochlea in the inner ear. There, they are converted into electrical signals by the hair cells and transmitted via the nerve pathways of the auditory nerve to the auditory centre in the brain, where they are finally translated into sounds and information.

From about the age of 50, the performance of the hearing in both ears decreases. In most cases, this is triggered by the natural wear and tear of the hair cells in the inner ear, sometimes the auditory nerve or the auditory centre are also affected by the ageing process. In addition, exposure to noise from leisure activities leaves its mark over the course of a lifetime.

Age-related hearing loss develops gradually and can often be compensated so well over a long period of time that those affected do not notice it. Especially at the beginning, the hearing loss initially only becomes apparent under acoustically difficult conditions, such as situations with a lot of background noise, a great distance to the speaker or in rooms with reverberation. Moreover, since the high frequency ranges are affected first, the impression may arise that women and children speak unclearly or mumble. It is only in the advanced stages that sensorineural hearing loss also becomes apparent in quiet surroundings, in one-to-one conversations, when watching television or using the telephone.

In Germany, about 14 million people are affected by age-related hearing loss. Yet only one in two uses a hearing aid to compensate for the hearing loss. The fact that this can have drastic consequences has become increasingly clear in recent years. If the understanding of conversation content is limited, those affected first try to compensate for this by asking questions or increasing the volume. Later, what is not understood is supplemented by association and guessing mechanisms based on the assumed meaning. The latter in particular requires a great deal of additional cognitive work and is exhausting. As the hearing loss progresses, many affected people withdraw more and more frequently in order to regain their composure, or they avoid activities that require good hearing from the outset.

Increasing social isolation and loneliness are known companions of old-age hearing loss and can in turn promote the development of depression.

Scientists at Columbia University investigated how close this connection is using data from more than 5,000 people aged 50 and over. Each study participant underwent a hearing test and was tested for depressive symptoms. They found that study participants with mild hearing loss were almost twice as likely to suffer from depressive symptoms as participants without hearing impairment. Participants with severe hearing loss were four times more likely to experience depressive symptoms than those with good hearing. Statistically, the risk of depression increased one and a half times for every 20 decibels (dB) of hearing loss.

In addition to social components, many researchers now also suspect a cognitive component that could favour the development of not only depression, but also anxiety and suicidal notions in untreated hearing loss. For example, it is known that untreated hearing loss alters the frontal brain region. This affects the ability to react appropriately to emotionally challenging or stressful situations and to regulate emotions as they arise.

Poor hearing also plays an important role in dementia. If acoustic and social stimuli are permanently missing, the brain is underchallenged. This can accelerate cognitive decline. At the same time, processing poorly perceived sounds and voices involves much more cognitive effort and creates stress in the brain that negatively affects the speech centre and working memory. All together, this appears to be a significant risk factor for the development of dementia.

Unlike with glasses, many people with age-related hearing loss are difficult to convince to wear hearing Aids. However, a study conducted by Shandong University in China, which analysed the data of about 430,000 people between the ages of 40 and 69, was able to prove how important this is in terms of dementia prevention. It showed that wearing a hearing aid reduces the risk of dementia in people with hearing loss to that of people with full hearing. Even in the case of profound hearing loss that was compensated for with a cochlear implant, an improvement in individual cognitive abilities could be demonstrated just a few months after hearing rehabilitation. Hearing Aids are also important for people with age-related hearing loss in order to remain as independent as possible and to receive good medical care.