Today hearing loss is referred to by degree rather than by a percentage. Hearing loss can be mild, moderate, moderately-severe, severe, or profound, and it can vary across pitches, which range from low to high, like the notes on a piano.
A hearing assessment is needed to determine the degree of hearing loss.
The intensity (volume) of sounds you hear is measured in decibels (dB), with 0 dB being equivalent to the softest whisper and 120 dB being equivalent to a jet engine.
The softest sound that a person can hear is referred to as a threshold. Normal hearing thresholds for adults are considered to be between 0 dB and 25 dB; anything outside of that range indicates a hearing loss.
Different Types of Hearing Loss
Sensorineural Hearing Loss
A sensorineural hearing loss occurs when there is damage to either the tiny hair-like cells in the cochlea of the inner ear, or the auditory nerve itself, which prevents or weakens the transfer of nerve signals to the brain. These blocked nerve signals carry information about the loudness and clarity of sounds and when this information can’t be transmitted to the brain normally, it results in hearing loss.
Sensorineural hearing loss is the most common type of hearing loss, and is generally considered permanent. This loss may stay stable or may continue to deteriorate over time.
The type of damage that results in a sensorineural hearing loss may be caused by: genetics, infection, medications, trauma, exposure to loud noise, or aging. Amplification by way of hearing devices is the most common treatment.
Conductive Hearing Loss
A conductive loss occurs when there is an obstruction or damage to the outer or middle ear that prevents sound from travelling to the inner ear. Conductive hearing loss may be temporary or permanent, depending on the cause. The inner ear remains unaffected with this type of loss.
A conductive loss may be caused by: outer or middle ear infections, earwax blockage, deterioration of the middle ear bones (ossicles), otosclerosis – fixation of the ossicles, a perforated eardrum, or a deformity.
Medical intervention and treatment can correct some cases of conductive losses, and amplification by way of hearing devices may be a recommended treatment option for others.
Mixed Hearing Loss
A mixed hearing loss occurs when there is a combination of a sensorineural hearing loss and a conductive hearing loss.