The Steam version of Titanfall has an audio bug, but there's a fix for it

Titanfall, Respawn’s multiplayer-only mech FPS from 2014, arrived on Steam out of the blue yesterday. Its user reviews are mixed right now, with some of the negative feedback coming from players who are having server issues, and others who have encountered an “unexpected parameter” error during installation that results in sound effects being replaced with a hissing noise.

Fortunately there’s a fix for that, as explained by Dj Sonic on the Steam forum. Find the file cam_list in your SteamsteamappscommonTitanfallvpk directory, then drag it onto the audio_installer in SteamsteamappscommonTitanfallbinx64. That should extract the audio files you’re missing, and although you’ll still see the error message, you should be able to hear actual sounds instead of static. Thanks, Dj Sonic.

source: gamezpot.com