Fast and soft

I have a friend who is kind of new. By that I mean we've been friends
only for about 6 months. I really like this friend and we get along
quite well, and I'm sure we would get along even better if only I could
understand what the hell she was saying half the damn time!! Not only
is this person a soft talker, but she is also a fast talker. Fast and
soft. Soft and fast. All the time. I get pretty sick of repeating myself
(What was that? Sorry what?) and so often I don't bother and just end up
making non-committal noises (yeah, mmm mmm) without even knowing what was said.

Now obviously I have two options here. I can continue the way it's been,
not say anything to her, and watch as our friendship sort of drifts along
and probably peters out somewhere down the track. Or I can gently and
tactfully raise the issue with her in the hopes that her condition then
improves and we might become closer friends because of it. I know this is
the decent thing to do, but the question is how.
Do I casually drop it in the conversation, like 'Yes, I love carrot cake too.
Hey, has anyone ever told you you talk very soft and fast?'
Or perhaps after a serious of whats from me, I could say 'Sorry about this.
I'm not sure if it's my hearing, but I always seem to have trouble trying to understand you. Isn't that funny?'
To which she would either get highly offended, or say 'Oh don't worry, that's
just me - I'm a notoriously fast and soft talker!'
To which I would reply 'Well will you please do something about it!'