Brittany- BRITT-ney. Two syllables.
Alana- uh-LAH-nuh.
Alanna- same.
Alannah- same.
Alyssa- uh-LISS-suh. Elissa- It's nearly the same, just the first syllable is very slightly different.
Erin and Aaron are both the same.
Carrie and Kerry are the same as well.
I'm from the US, northeast.