Different Types of Hearing Loss
There are three primary types of hearing loss: Conductive, Sensorineural and Mixed
Hearing loss is described by varying degrees at various pitches and is classified as mild, moderate, moderately-severe, severe, or profound. The volume (or intensity) of sounds you hear is measured in decibels (dB), with 0 dB being the softest whisper and 120 dB being a jet engine. The softest sounds a person can hear are called thresholds. Normal hearing thresholds for adults are considered 0 to 25 dB.
Conductive Hearing Loss
Conductive hearing loss occurs when there is a problem with the way sound is conducted to the inner ear and the cochlea. The problem may lie in the ear canal, eardrum (tympanic membrane), or the middle ear (ossicles and Eustachian tube). The inner ear remains unaffected in this type of hearing loss.
Symptoms of Conductive Hearing Loss
Individuals with conductive hearing loss may report that sounds are muffled, low or quiet and may describe a plugged or fullness sensation in the ear or head.
Causes of Conductive Hearing Loss
Some causes of conductive hearing loss can include: Outer or middle ear infections, earwax blockage, deterioration of the middle ear bones (ossicles), otosclerosis (fixation of the ossicles), and perforated tympanic membrane (hole in the eardrum).
Conductive hearing loss may be temporary or permanent, depending on the source of the problem. Medical management can correct some cases of conductive hearing loss, while amplification may be a recommended treatment option in long-standing or permanent cases.
Sensorineural Hearing Loss
Sensorineural (sen-sor-ee-nuhral) hearing loss occurs when there is a problem with the sensory receptors of the hearing system, specifically in the cochlea of the inner ear, typically called a nerve loss. The majority of sensorineural hearing loss occurs as a result of an abnormality or damage to the hair cells in the cochlea. This abnormality prevents sound from being transmitted to the brain normally, which results in a hearing loss.
Symptoms of Sensorineural Hearing Loss
Individuals with sensorineural hearing loss may report muffled speech, ringing in the ears (tinnitus), difficulty hearing in background noise, and/or complain that others do not speak clearly.
Causes of Sensorineural Hearing Loss
Some causes of sensorineural hearing loss are congenital (abnormal since birth), damage to hair cells (as a result of genetics, infection, prescription drugs, trauma, or over-exposure to noise), presbycusis (damaged as a result of the aging process).
Sensorineural hearing losses are generally permanent and may stay stable or worsen over time. Routine hearing tests are needed to monitor the hearing loss. Amplification is the most common treatment, which includes hearing aids or cochlear implants in the most severe cases.
Mixed Hearing Loss
Mixed hearing loss occurs when a person has an existing sensorineural hearing loss in combination with a conductive hearing loss. This type of hearing deficit is considered a mix of sensorineural and conductive hearing losses, which means there is a problem in the inner ear as well as in the outer and/or middle ear.
Treatment for a mixed hearing loss may be a combination of medical treatment and amplification (hearing aids).
Contact Dr. Coughlin at Hearing Care Professionals if you have questions about types of hearing loss.