A common experience is to hear faint beat of your own heart, normally after a vigorous workout. However for Stephen Mabbut, the noise of his own eyeballs moving in his head was so loud and audible it was driving him mad. This frightening experience was later attributed to a rare condition, superior canal dehiscence syndrome.
http://www.news.com.au/weird-true-freaky/stephen-mabbutt-hears-own-eyeballs-diagnosed-with-superior-canal-dehiscence-syndrome/story-e6frflri-1226106232464
He added, "The first symptoms appeared around 2005. I found if I raised my voice, I'd get a vibration in my head. If I was eating a bag of crisps, the crunching noise drowned out people speaking. Then I found I would be hearing my heartbeat."
But this year, a CT scan showed a tiny hole in the temporal bone in Mr Mabbutt's skull, which meant that fluid from the semicircular canals of the inner ear was leaking into his brain and conducting internal sounds.
http://www.news.com.au/weird-true-freaky/stephen-mabbutt-hears-own-eyeballs-diagnosed-with-superior-canal-dehiscence-syndrome/story-e6frflri-1226106232464
@Gnarls, block both your ears while eating chips and then you'll know what it sounds like for him.
@Gauldar, unforch only internal sounds are amplified. People with SSCD may experience hyperacusis - an oversensitivity to sounds - which may cause them to percieve more environmental sounds as uncomfortably loud, but that doesn't mean their hearing is actually improved. In fact, they generally have conductive hearing losses.