The hearing anatomy is composed, at a high level, of outer ear, middle ear, and inner ear. Between your ear drum and your inner ear (aka cochlea) is a set of 3 bones that conduct the sound waves mechanically. They are called
the malleus, incus and stapes. These bones are meant to transmit the sound as faithfully as possible, and they are responsible for the "conductive" part of the hearing. Sometimes there is a pathology in these bones. In that case, there is a chance surgery can help. A stapedotomy is essentially a replacement of the stapes bone (the smallest bone in the human body) with a prosthesis (nowadays often made of titanium). There are more complicated surgeries where the whole ossicular chain is reconstructed. The goal is the same though: re-create the mechanical linkage between the ear drum and the inner ear.
Once the mechanical wave hits the inner ear, it is transformed into electrical impulses through the whole cochlea processing (organ of corti). That area is responsible for the "sensorineural" part of the hearing. As of today, we don't really know how to fix those, or even how to pinpoint with accuracy where the issues lie.
When you get a hearing test, you get sound from 2 sources: a small speaker into your ear, and some kind of buzzer on a head bone (often mastoid). The former tests "air conduction" (going through the middle ear bones), and the latter bypasses that. A difference between an Air and Bone measurements is called an "air bone gap", and is indicative of conductive losses (since bypassing the middle ear bones yields better results).
If you have conductive losses, there is a chance that something can be done for you (some of these surgeries have been performed for about a century). Another easy way to test for conductive losses is to do a
Rinne test. In general, you want multiple tests run to get more confidence in the results, because the only way to truly confirm is to "go in and check", which involves opening up your eardrum to "see what's behind" (which is quite invasive).
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