Iíve noticed that if I have earplugs or ear bud style headphones in my ears that chewing food sounds incredibly loud, but when my ears are unplugged itís much more quiet. Why is that?
Trevor Cox, Professor of Acoustic Engineering, University of Salford:
This phenomena is well-known to audiologists and hearing-aid providers. It is called the "occlusion effect".
I have noticed people singing in groups using this effect to adantage by sticking a finger in their ear so they can hear their own voice better. See Steeleye Span.
Could it be because our sinuses are in the same distance/region
Quoting from the link I gave earlier...
The Ear is an incredibly sophisticated system for getting sounds in without suffering from interference from internally generated sounds. The cochlea, which contains the actual sound sensing cells is fed with two sound signals - not just one. The 'oval window' is vibrated by the three tiny bones (the ossicles) which link it to the ear drum. It and the Ear drum are also subject to vibration of air in the Eustacean tube - this tube joins to the other cavities inside the head (nose, mouth and sinuses). So if you blow your nose or sniff etc., you would hear a very loud noise. To avoid this, there is another window - the 'round window' which also takes sound from inside the middle ear. The Cochlea senses the DIFFERENCE between signals from the two windows - which is the sound from the drum, via the ossicles. Any other internal sounds are canceled out because both windows are moved in the same direction.
That's a really nice answer SC. It's also the way "balanced" audio electrical equipment works to miminise noise in lines and mic leads. In this situation the signal is applied to one of three leads, the other two being a ground and a neutral line.
Thanks for the kind comments.