A320 Captain describes loud static in the radios while deviating around thunderstorms; making communication impossible.

Narrative

Enroute we deviated east of two Level 4-5 thunderstorms downwind by 45 NM. As we entered some remaining moisture from a dying downwind cell (looked like a thumb print on radar; not fully colored in and only green spotty); we began to see St. Elmo's fire and the radios got loud with static. In about a minute the radios were completely unreadable. We advised ATC of static and that they were very unreadable. We could faintly hear their reply. We were on a heading of about 130 and advised in the blind. We also broadcast on 121.5 and sent a text to Dispatch. The loss of radios lasted about 5 minutes or so where the radios were severely loud and unreadable! There was another aircraft; I believe an A340 that was 1;000 FT below us within a few miles that ATC had alerted us on. The concern is that radios should not fail so badly in moisture and conditions we were in as I have been in similar conditions hundreds of times without any failures or such static. I have also been in light moisture (green return no cells) conditions and experienced static and wrote the radios up to maintenance. They advise the antenna casing gets cracks and allows moisture to get in thus static is created. Note both radios (Captain/First Officer) had the same problem on different frequencies. This was a very disconcerting and unsafe event; especially with multiple airplanes deviating; vectoring; and switching altitudes for thunderstorm avoidance.