Simple... If ur game is currently in English, just firstly download these 3 files;
http://www.filedropper.com/ofcorespeechenglish
http://www.filedropper.com/offullspeechenglish
http://www.filedropper.com/ww2axisspeechenglish
Then just go to ur already installed 'CoH New Steam Version' folder directory inside ur Steam system folder usually found on most computers at the desk called "C" where u will find all the original game files listed! Open the folder called "WW2" and then the one called "Archive" as that u should be at this point seeing 17 '.sga' files.. all what u will have to do is to copy the following 3 files:-
OFCoreSpeechEnglish.sga
OFFullSpeechEnglish.sga
WW2AxisSpeechEnglish.sga
Plz save or back them up to a safe place on ur pc just in case!
Now, copy the ones of which u have downloaded in replace of them but watch out, it's much more highly recommended if u firstly remove the already existing ones and not to overwrite them by the new downloaded ones

I guess I don't have to explain how to do it if ur game wasn't primarily in English because u will then clearly just have to rename the last part of the downloaded files to the same language name that the game is currently using ^^
Thanks to the player Danjel.. he did a great effort uploading those files!
Also btw... u can change any of ur Steam games whole operating language by just right clicking on the game at ur Steam library then choosing ur favored language but u have to keep in mind that this will require the game to suddenly update about 1GB or more.
Enjoy

Note:- it's worth to mention that we actually don't know who created this idea in first place so credits are honestly 'unknown' after anyone...