For a discussion on kol isha, see the Mishneh Berurah (75:17) where he initially states that kol isha of a p’nuyah (single girl) is muttar. He then modifies that to exclude Jewish girls (because of chezkas niddah) and non-Jewish girls (because of ervah). So only a Jewish single girl who is tahor would be permissible, and even then only without any thoughts of arayos. Basically, kol isha is assur.
So a kallah the day of the wedding before the chuppah would not be assur?