What is the difference between conduction deafness and nerve deafness?

Answer 1

partial or total inability to hear. The two principal types of deafness are conduction deafness and nerve deafness. In conduction deafness, there is interruption of the sound vibrations in their passage from the outer world to the nerve cells in the inner ear. The obstacle may be earwax that blocks the external auditory channel, or stapes fixation, which prevents the stapes (one of the minute bones in the middle ear) from transmitting sound vibrations to the inner ear. In nerve deafness, some defect in the sensory cells of the inner ear (e.g., their injury by excessive noise) or in the vestibulocochlear nerve prevents transmission of sound impulses from the inner ear to the auditory centre in the brain. Deafness at birth is nearly always of the nerve type and cannot be improved by medical means.

Answer 2

To understand this difference, you first must have a basic knowledge of the human ear, and how it is organized. There are 3 main parts of the human ear: the outer ear (or ear canal), the middle ear, and the inner ear (or the cochlea). The outer ear is responsible for catching sound, and funneling it into the middle ear space. The middle ear is the space with 3 tiny bones that move back and forth together to send vibrations of sound to the inner ear. The inner ear is a snail shaped organ filled with fluid. When the middle ear transfers energy caused by sound to the inner ear, it creates waves in the inner ear’s fluid. The waves in the fluid move cause movement in tiny hair cells (found inside this fluid) that are connected to our auditory nerve. When these hair cells are moved around, they signal our brain to sound.

A conductive hearing loss is one that blocks conduction of auditory signal. This could be caused by any disease or disorder that blocks sound at the level of the outer or middle ear, and essentially acts as an ear plug. Ear infections, fluid in the ear, tumors, growths, scarring, or ear malformations are all different things that can cause conductive hearing loss.

A sensorineural hearing loss on the other hand is a hearing loss caused by damage to the cells within the cochlea (inner ear). In the case of sensorineural hearing loss, the sound may be conducted appropriately from the environment, to the outer, middle and inner ear, but the hair cells are not appropriately triggered. This is usually a result of death or damage to the hair cells of the cochlea, and may be caused by ototoxicity (chemical/drug damage to the cells), loud noise exposure, or simply cell death due to hearing loss (presbycusis).