I was once in a shul which had both a chazan and a choir. When it came to modim on Shabbos mussaf, the chazan sang the first few words of modim and this was followed by the choir singing the first few words of modim d’rabbonon. The chazan then sang the next few words of modim and the choir then followed with the next few words of modim d’rabbonon. This then went on throughout modim and modim d’rabbonon. I must say that it was cleverly arranged musically. However what the congregation in fact heard was a “jumble” of words. Is such a musical rendering problematic halachically?