Severity	Degree of hearing loss in better ear (dB)			Examples of sounds that can or cannot be heard
	Clark model19	Centers for Disease Control and Prevention model20	World Health Organization model21
Normal	10 to 15	≤ 25	≤ 25	Can hear normal breathing
Slight	16 to 25	—	—	Infrequent difficulty in some situations; can hear whispering from 5 ft (1.5 m) away
Mild	26 to 40	26 to 40	26 to 40	Difficulty hearing soft speech, quiet library sounds, or speech from a distance or over background noise
Moderate	41 to 55	41 to 55	41 to 60	Difficulty hearing regular speech, even at close distances, or sound of a refrigerator
Moderately severe	56 to 70	56 to 70	—	Extreme difficulty hearing normal conversation; can hear electric toothbrush
Severe	71 to 90	71 to 90	61 to 80	Cannot hear most conversational speech, only loud speech or sounds (e.g., an alarm clock)
Profound	≥ 91	≥ 91	≥ 81	May perceive loud sounds (e.g., factory machinery, car horn) as vibrations