I came across this on the RICKA BBS. Interesting reading, especially for the rolling afficionados among us.

http://www.nrsweb.com/safety_tips/what_is_kayakers_ear.asp?roi=echo4-17213050365-14323836-4fc1684a00683a1da019686cb48ac34e&fc_c=3825507x14323836x118025598&utm_campaign=newsletter&utm_medium=email&utm_source=rtn0112b&utm_term=nl_safety_tips_kayakers_ear