Loudness Recruitment

Loudness recruitment is a phenomenon associated with sensorineural hearing loss in which sounds grow in perceived loudness much faster than normal once they become audible. A person with loudness recruitment may need a sound to be louder than typical before they can hear it at all (due to elevated thresholds), but once that threshold is crossed, the sound rapidly becomes uncomfortable as the volume increases further.

This happens because the cochlea's outer hair cells, which normally fine-tune and expand the range of comfortable hearing, are damaged or missing. The dynamic range of comfortable listening (the range between the softest audible sound and the loudest tolerable sound) becomes compressed. Someone might say "don't shout, I'm not deaf" despite having a significant hearing loss, which reflects loudness recruitment rather than contradiction.

Loudness recruitment is an important factor in hearing aid fitting. Wide dynamic range compression (WDRC) in hearing aids is specifically designed to address this by amplifying soft sounds more aggressively while limiting the amplification of sounds that are already loud enough to be comfortable.