i can hear it while under acceleration sometimes, it sounds like water leaked out into something under the dash, i have no idea, i think i seen a thread about this before but didnt read about it, anyone else notice this,
do you notice any coolant under the car (behind front passanger side wheel?) if so its your heater core ..i was hearing the same noise and i was leaking a little coolant ,,replaced it and is back to normal...does your heat smell kinda like anti freeze?
i think it might need bled out, cuz when the car heats up above normal while sitting, becuz the fan doesnt turn on till i hit the a/c, and when i rev it up a little i can hear bubbles, soo i might just bleed it off and see how that works.
THis happened to me when I flushed the fluid on my old Camry... It sounds like there is just excess pressure in the cooling system... I alleviated it simply by openning the valve once it got warm (not adviseable) but a simple bleed will most likely fix this.