This is the sound of my diabetes. When I was diagnosed in 2007 this came along for free and has been my constant companion 24hrs per day. Various foods will boost the volume for a while, particularly apples. No-one seems to be able to explain how this came about or how it works, so I made this using a waveform generator and audacity, to create an overlay to capture the 'swish' or shift (move your head around near the speakers). 
I am posting this for British tinnitus awareness week - see http://www.tinnitus.org.uk/ and http://www.jisctechdis.ac.uk/techdis/userneeds for info. 

terrymc