Conductive Hearing Loss:
This type of hearing loss is caused by problems in the ear canal and/or the structures in the middle ear. It occurs when sounds from the outside world cannot be transmitted normally through the ear canal and/or middle ear to the inner ear. The most common causes of conductive hearing loss can be a buildup of wax in the ear canal, a perforated eardrum, fluid in the middle ear (common in children), or damaged or defective ossicles (middle ear bones). A person with conductive hearing loss may notice their ears seem to be full or plugged. Most conductive hearing losses can be medically or surgically treated. If for some reason the hearing loss cannot be corrected, hearing instruments can provide benefit.
Sensorineural Hearing Loss:
This type of hearing loss is the most common type of hearing loss. More than 90 percent of all hearing instrument wearers have sensorineural hearing loss, resulting from problems in the inner ear or the auditory nerve. Inner ear hair cell damage is the most common reason for sensorineural hearing loss. These tiny hair cells, once damaged or destroyed, become unable to convert sound vibrations in to the electrical signals needed by the auditory nerve. Sensorineural hearing loss can be attributed to long-term occupational or recreational exposure to loud noise. It also commonly occurs in the later decades of life. People with sensorineural hearing loss typically report they can hear people speak, but can’t understand what they’re saying. It often seems to them that people are “mumbling.” Usually there is no medical way to correct this, but hearing devices often help.
Mixed Hearing Loss:
This kind of hearing loss is caused by a combination of problems in the middle and the inner ear or the auditory nerve. For example, the person may have a noise induced hearing loss from noise exposure and a perforation in the eardrum. The combination of sensorineural and conductive hearing loss is therefore, mixed.
Is there an explanation for why a high frequency hearing loss can be momentarily restored, repeatedly, simply by pressurizing the middle ear? I am interested to know if this restoration can be established permanently.
Hello Graham,
Thank you for your interest and question. Changes in middle ear pressure can both enhance or diminish auditory sensitivity depending on the effect it has on the tympanic membrane and ossicular chain. Ideal function with best result across the majority of frequencies we hear will be achieved at pressure equalization to outside air pressure. Over or under pressurization will have a small effect on high or low frequencies and will be temporary. Despite the perception of a “noticeable” improvement in clarity or hearing, actual measurements reveal a change of less than 5 dB in practice (less than the resolution of the average audiogram which is measured in 5 dB increments).