check out this thread from a long time ago... I only have this trouble now down around 80 or 90' when the going gets a little tough.
http://forums.deeperblue.net/showthr...ighlight=heard
AND you can hear it hear as I near 90' in this video...
http://www.zippyvideos.com/901329870...eediving30fps/
I have less trouble the more air I can keep in my mouth to use for equalizing... but when that air gets used up, it's tough.. have to bring more up from the lungs and concentrate on the equalization.