> We don't have to scream but if we don't speak 'clearly', she misses a lot, especially when we are with a larger group (say 10 people at a dinner). She says she has some friends that she understands very clearly, in contrast to others (admittedly, me and one of my sisters are not the best examples of how to speak crystal clear).

This is where my normal hearing is now. My assumption is the "some I understand clearly" is base very much on what frequency their speech is in.

I'm meeting with a hearing aid doctor this week, actually.