When entering the End via an End Portal, the travel.ogg sound effect can be heard, but it sounds really quiet - like it's either behind something or rather far away. The sound can be heard correctly when entering the End in vanilla 1.12, or on the wiki here (although it's pitched down a little in-game).

This was due to the sound being converted to mono. This should be fixed in the next release, here is a preview build in the meantime.

EDIT: The build posted has a bug with Dynamic Surroundings that doesn't lower the volume properly of some sounds, here is a fixed build.