My children have cd’s of kids’ songs that also have a woman singing. Am I permitted to listen to these songs with them? What about in general? I have heard that if you do not know the singer or what she looks like, it is OK. Is this true?

According to some authorities a man may listen to a woman singing on tape if the music is not provacative and he doesn't know her. I assume the childrens' songs are not provocative.