I assign my inability to properly pronounce the sound represented by 'll.'
This may seem unimportant for someone living in Pennsylvania, but it's actually significant hereabouts because a lot of place/street names incorporate the sound.
For instance, if I scan my regional street map I find:
Llanerch
Llandaff
Llanwellyn
Llewellyn
Llanfair
I know it's not correct, but the ll tends to be treated as a lengthened single l. Just as the place named Bala Cynwyd is misprounced here as Bala C
in-wid. I have a feeling I've been misprouncing Bryn Mawr, Bryn Athyn and Gwynedd too.