its humurous how ignorant people like you can be. first of all consider what words are- representations of an object. i say table and that correlates with a table. yet deaf people do not have this connection. they SIGN table, which correlates to table. they may spell and know words, but as far as sounds, they do not know this. so i pose this question to you, how can they think in sound? which is what the original question is. they cannot think in words or letters, for htis is impossible. therefore they must think in sign.
by the way caps was unnecisary, we can see how stupid you are without them