by Neil Bauman, Ph.D.

A lady wrote:

My hearing loss has been described as “an air gap in the bone.” Whatever do they mean by that?

What you really mean to ask is, “What is an air/bone gap?”

When your audiologist does the pure tone hearing testing (the series of beeps at different frequencies and intensities), the “air” refers to “air conduction” testing using earphones, and the “bone” refers to the “bone conduction” testing using a bone oscillator (vibrator) placed behind your ear on the mastoid bone.

If you have a sensorineural hearing loss (meaning inner ear loss) both the air conduction and the bone conduction results will be similar.

However, if you have a conductive loss (meaning a middle ear loss) then your bone conduction testing results will be better than the air conduction results on your audiogram. This difference between the two lines or your audiogram is called the “air/bone gap”. Thus, the gap is only on your audiogram; it is not a physical gap in some bones in your head.

You could also have both a conductive and a sensorineural hearing loss at the same time. They call this a mixed loss. In this case, you will also have an air/bone gap on your audiogram.