Hallel

As long as one is sure he'll be able to hear all of the chazzan's words, he should be youtzei from the chazzan Youmru No etc. and should say only Houdu after every paragraph. If one may not here everything, he should say quietly and together with the chazzan his parts, and then say out loud (after the chazzan finishes) Houdu. In any case one should not hurry and say Youmar No etc. before the chazzan.

Michael FRBSH