Alright, this tutorial will be extremely easy to follow, no sound alias needed or anything else.
First of all you are going to need a black ops converter tool, literally get the black ops sound transcoder from here [You are not allowed to view external links.
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and get all of your sounds convert them same as you would do in cod waw(.wav) and then just open the tool and and drag your .wav files there, and the sound transcodcer will convert your files in the bo1 format.
I will start with round sounds. To change round sounds you need to have your sounds ready and converted, and after that you go to black ops 1directory, mods/mapname/sound , if the sound folder doesn't exist, then just create it. After that open the sounds folder from there and make a new folder called "mus", open that folder and inside of it again make a new folder called "zombie". Once again you open that folder and make a new one called "zombie_global" and there you can put your round sounds together with the dog round sounds. You have to rename your sounds in a specific way.
round start - mus_zombie_round_start
round end - mus_zombie_round_over
dog round start - mus_zombie_dog_start
dog round end - mus_doground_end
So literally this is the location Call of Duty Black Ops\mods\YOUR MAPNAME\sound\mus\zombie\zombie_global and you paste your converted and renamed sounds there.
Now to change the perk jingle and sting sounds you need to sill make these new folders(unless you already have them) and go to this location
Call of Duty Black Ops\mods\YOUR MAPNAME \sound\mus\zombie and at the folder called zombie, make a new folder and name it "perksacola" and there you have to paste your sounds and rename them in a specific way.
So, literally in this location Call of Duty Black Ops\mods\YOUR MAP NAME\sound\mus\zombie\perksacola you paste your own sounds and just rename them.
And finally, to change the game over sound same as for the round sounds and perk sounds, you go to the same location Call of Duty Black Ops\mods\YOUR MAP NAME\sound\mus\zombie and make a new folder called "game_over" , and inside there get your sound and rename it to "mus_gameover_abracadavre" and paste it in the "game_over" folder. And that's literally it. I am pretty sure that there are other ways to change these sounds, through sound aliases but this process is really quick tbh.