Definitions of impairment:

• noun:   damage that results in a reduction of strength or quality
• noun:   a symptom of reduced quality or strength
• noun:   the act of making something futile and useless (as by routine)
• noun:   the occurrence of a change for the worse
• noun:   the condition of being unable to perform as a consequence of physical or mental unfitness

  Example: "Hearing impairment"