You know you have a hearing loss because every single person you know complains that you can’t hear. You know you need to get it checked and you know you shouldn’t put it off. But what doesn’t make any sense to you is if you have a hearing loss then why do loud sounds bother you?
What you’re experiencing is a condition called “recruitment”.
Recruitment is an abnormal growth of loudness, in other words, a tone cannot be heard due to hearing loss until it reaches a certain loudness, then it becomes a loud sound, very quickly rather than the gradual increase in loudness experienced by people with normal hearing.
Recruitment causes your perception of sound to be exaggerated. Even though there is only a small increase in the noise levels, sound may seem much louder and it can distort and cause discomfort. Someone with recruitment can have problems only with specific sounds and frequencies or may have problems with all sound in general.
The theory of recruitment is that as the hair cells in your cochlea become ineffective, they get help or “recruit” their (still working) neighbor hair cells to “hear” the frequency (think pitch) the damaged hair cell was supposed to hear. In addition to the frequency the still working hair cell was supposed to hear. This increases the signal from the still working hair cells making the sounds reaching our brains appear to be much very loud sound, much louder than they’re perceived by people normal hearing.
The net effect is that people who have recruitment along with their hearing loss will experience an increasingly narrow range between the softest sound they can hear (caused by the hearing loss) and the loudest sound they can comfortably tolerate (caused by the recruitment).
Not everyone with hearing loss is also bothered by loud sounds. It’s a condition of the hair cells and their nerve endings in the cochlea. So, people whose hearing loss comes from other sources (such as conductive losses or nerve losses not involving the cochlea may not experience recruitment.
Recruitment is a condition that must be managed when fitting and programming a hearing aid. The best news of all, recruitment levels can be increased over time as hearing aid use increases and re-stimulates the hearing system.