The Byron BY301 & 302 wirefree portable door chime kits have a choice of 8 extra loud melodies (90-94dB rating on the sound). They have volume control & self learning.
Chime requires 3 x C batteries (NOT included).
Push requires 1 x CR2032 battery (included).
The Byron BY301 has the following features:
Operating distance: 100m
Flashing light alert for the hard of hearing