The four degrees of hearing loss are mild, moderate, severe and profound hearing loss, according to WebMD. Doctors sometimes diagnose the degree of hearing loss a patient is suffering through a test called an audiogram.
Normal hearing typically involves hearing sounds as low as 10 decibels, which is approximately the volume of human breathing, according to WebMD. The clinical threshold for mild hearing loss starts at 26 decibels and ends at 40 decibels; patients with mild hearing loss are typically able to hold normal conversations but may struggle if there is background noise. Moderate hearing loss, which affects the 41- to 55-decibel range, can make normal conversation more difficult both in person and over the telephone. Sufferers may have to ask the people they're talking with to repeat themselves.
Severe hearing loss starts at 56 decibels and ends at 70 decibels, states WebMD. Those with severe hearing loss typically need a hearing aid for normal conversation, as the range covers even loud human speech. Profound hearing loss begins at 90 decibels, and those who suffer from it find normal conversation impossible without a hearing aid or cochlear implant. People with profound hearing loss may be able to make out sounds such as nearby jets or car engines backfiring.