Newbie's guide on how to be quiet before you get us all killed (expert input from community welcome).

OK I promise to limit ranting in this post because people say I am too mean, lol. I did limited tests on a lot of the contents so please reply if you spot any error and I can do additional testing and edit this. Any content I might have missed is welcome.

This is very long, is there a TL:DR version?

No, silence is a complicated mechanic in this game, so it will loses valuable information if it's too short. There's a lot of weird mechanic going on, so you gotta pay attention to what you do. In extreme mode, one casual mistake can leads to a wipe.

But I don't wanna....I just want easy answers.....

Sorry, then this guide is not for you if you don't like reading. Maybe Britney can make one with pictures :)

What's the consequence when breaking silence/Stealth?

Once you break silence, the AI director will spawn group of zekes and specials that comes your way, and it keeps doing that at interval until you start the finale fight. On normal/hard, those few extra wave isn't too big a deal, and you get few specials that spawn. But on Insane/Extreme, it's one sure way to get everyone killed (Yes, 4 veterans can battle through that with minor scuff sustained, but this guide ain't for them. Newbies WILL DIE when they break silence, especially in small area with little room to maneuver). I've seen wipe outs often as early as hard mode, especially when they don't take care of those specials quickly. I finish killing my side and find all 3 teammates on the ground getting beat up by bulls.

If you can maintain silence though, the non-horde fights will be a lot easier, and you can save all your heavy weapon/med kit/equipment for the finale battle, where one extra heavy weapon can make or break the game (just ask all those people who failed on Tokyo 2).

Do I have to be silent all the time?

No, this game has a silence phase and loud phase. Loud phases are those big scripted horde/swarm battles where you get large fixed waves coming at you. It's only during silence phase where you need to remain silent to avoid additional spawns.

When do I know when silent phase ends and when it starts again

Each map is a bit different, usually loud phase starts when you enter the horde battle area and the count down clock starts. On maps without count-down, it's when the on-screen prompted to start the event appear (note that on horde battle without count-down clock, AI director will send you waves if you stand around doing nothing for TOO long). If you have bot teammates, you can tell when loud phase starts or if you broke silence since they will immediately whip out their primary weapons instead of sticking to their pistols.

Loud phase only end for mid-chapter finales (duh) when you leave the battle area, usually through a locked door, gate, etc that was previously blocking your progress. For example, in Jerusalem2, the loud phase ends when you leave the dam through that locked door onto the inside of the dam. In Tokyo2, the mid-chapter loud phase actually starts when you start escorting the bus and ends when it finally goes through the gate and you exit through the metal gate to the left.

Silence can be "Reset" after broken:

If you break silence in earlier part of the game, it doesn't mean it will continue the whole map. Most noticeably, you are reset back to silent status after the mid-chapter horde fight, and I suspect that silence is restored each time you enter a new area (i.e. areas that were previously locked off to you) after you leave the "loud" zone. I haven't been able to test each map though. Your best practice is to stick to silent except in those horde fights.

So exactly what break silence?

1. Primary/secondary guns: Check your weapon customization to see if your currently selected primary/secondary weapons are silent (weapon characteristics are display to the left of the weapon 3D model). Read CAREFULLY because some weapon looks like it's got a silencer, but it's actually a muzzle suppressor that's loud. I see this newbie mistake a lot. Firing a loud gun few times will immediately break silence.
2. Unlisted secondary weapons: revolver, saw-off shotgun, and flare are loud. But strangely, the grenade launcher + its variant is QUIET. (Yes that's weird, and it has been tested before).
3. Equipment: Gunslinger's grenade, claymore, and C4 breaks silence. But fixer's explosive ammo is not considered loud if you fire it using a silent weapon (although it does attract zekes in the immediate area of the shot). Stun gun, gas mask, molotov, and stim pistol are quiet.
4. Heavy weapon: RPG, MGL, Machine gun, assault shotty, explosive sniper, and chainsaw are all loud. I haven't been able to test flame thrower since it's not a starter weapon.
5. Breach charge: Breach charge are definitely loud and they will trigger a wave when used. The best thing to do is don't breach when outside of finale battle. Since most breach-able doors are in the finale area, do those instead. After the door breaches, kill any spawn zekes first. I see this mistake a lot, people just run in and start browsing, and then find themselves boxed into the container of death with 10 zekes + bull waiting outside.
6. NPC soldiers: Their rifles are not silenced. For Example in Tokyo2 before you get to the bridge, you will hear soldiers shooting coming from the bridge and that always breaks silence. The one that really kills you is Tokyo3 after the engine room. You can come up to the main deck with some soldier shooting (it's random spawn). It breaks the silence for you and can spawn screamer immediately, that one hurt because the waves are big and you could already be low on ammo.
7. Other environmental items: Red turrets breaks silence when they start shooting at you or the zekes. Some cars also have alarms. One shot to the car will set the alarms off and break silence. Those red gas tanks you see everywhere also break silence if you shoot it. (Yes I am looking at you people who shoot at those tanks under the museum in NY3. Stick to melee only under there for god's sakes. It's only like 5 fucking zekes in that hallway, stop shooting)
8. Running: Best advice about running is: Don't. I haven't fully tested it myself but running long distance will alert zekes in your immediate area but doesn't break silence (at least not in hard and below). I will have to test on insane/extreme later. Others experience horde spawn right away. It's highly possible that devs implemented the running rule differently according to difficulty and area of the map, so by default you should not sprint.

Ha! You are wrong! I just made a bunch of loud noise and nothing happened.

One of the following could be in effect:

1. You are still in the "loud" zone.
2. Someone already broke silence but new wave hasn't been spawned yet. (AI director does not send new waves non-stop. There are cool down periods).
3. You are in a "safe" zone. Besides the maps starting zone, there are certain area where no zeke spawn point are present (like the locked room after you climb the stair of raining zombies in NY2). Once you exit the safe area though, you will immediately see zekes starting to drop on you.
4. You are in a scripted spawn zone. Some areas, like the Tokyo 2's fuel depot, has fixed zeke wave spawn pattern based on your action or timer. So even if you go loud, the director will not spawn waves of specials.

Ha! You are wrong! I am silent but zekes waves are still spawning.

1. Someone else on your team fucked up and broke silence. Yup it's one of your teammates (it's never your fault right?)
2. You are in a scripted spawn zone.
3. See Running from previous section.

Shit, I just broke silence, are we screwed?

Well it's not great, but shit happens, stick to these points below and you just might make it.

1. Don't panic. I can't stress this enough. WWZ works just like any zombie movie you've ever watched. The first guy that panic and start running away from the group ALWAYS dies a gruesome death.
2. Do not whip out your heavy/explosive weapons and start going Rambo on everything while yelling "Leeroy Jenkins!" Using more loud weapons will attract more and more zekes, stick to your silent strategy. Only use more loud weapons if you absolutely have to.
3. Don't rush forward even if you are near a finale area, those zeke will just follow you in. They don't automatically disappear you know. Setup defensive positions on or near you current location, and kill any zekes that spawn before moving on. Do not engage them in a running battle, it's not going to end well because you are not trained soldiers. (OK few of you might be, but your teammates won't be).
4. There are few exception to rule #3 when you are expected to run towards a safe area. In that case just run but don't forget to cover your teammates.
5. The worst thing that can happen is when 4 guys split up into 2x2 groups or scatter everywhere. Re-group ASAP if that happens and follow rule #3 above.
6. If you are alone and lagging behind or too far ahead, rejoin your teammates ASAP. Tag the area where the zekes are coming from so they look/shoot that way. Don't just run pass them and leave them to deal with the mess you just made (In the movie, that's the guy everyone hates and dies badly towards the end)