There are many reasons why people who were born with hearing can lose it in later life. The most common is wear and tear and is a normal part of the ageing process. It's usually gradual and you might put up with it for years before accepting that you need help. Another cause is noise exposure at work or at leisure. This can be from a short burst of sound (like a firework), or from longer exposure, for example, working in a noisy factory or standing next to the speakers in a nightclub. Illness, injury and medication are other reasons why your hearing might deteriorate.