Some people's voices (male or female) seem to have a clarity and sincerity that makes me, at least, take notice of them.

I think ladies that sound happy, confident and maybe just a little flirtatious (sp) are very sexy, even if the relationship itself is only that of being friends.

Going the other way, my wife loves how Tom Selleck, James Garner and Sean Connery sound and thinks they are very sexy. I can understand that and think it's neat for her to share that with me.