His resulting hearing impairment over the past few years is most likely the result of listening to loud music for for long periods of time. Studies show that you can lose your hearing by listening to loud music for a long time, or even listening to music with earphones or headphones for long periods of time.
Just like nerve cells recieve signals in the skin inside the auditory cochlea of the ear there are sensory hair cells that sense vibrations in the cochlea fluid and convert them into signals. Excessive listening of loud music causes an excessive vibration of these hair cells damaging them hence they will not recieve the signals from the oval window dissipated into the cochlea fluid. They convert the vibrations into electrical signals that are recieved by the auditory nerve to be taken to the brain for interpretation. The brain then interprets the signals as sound. The intensity of vibration and its pitch is what is determined as either loudness of lowness of a particular sound.
