• CustomSwitchData - stores information about custom switches.
• SoundManager - the core class of SoundAPI that allows you to add custom switches, load soundbanks and register stop audio events.
• StopEventType - an enum with all types of global stop audio events.
• SwitchedEvent - stores an event name, a switch group and a switch.

There are four methods to load custom soundbanks - SoundManager.LoadBankFromModFolderOrZip(module, fileName), SoundManager.LoadBanksFromModFolderOrZip(module), SoundManager.LoadBankFromModProject(path) and SoundManager.LoadBanksFromModProject()
All of them are best called in the Init() method of your module.
All of them in detail:

• SoundManager.LoadBankFromModFolderOrZip(module, fileName) loads a soundbank with the file name of fileName (fileName doesn't need the .bnk at the end) from your mod's folder/zip. You can use it in your module like that: this.LoadBankFromModFolderOrZip("name of your soundbank file here")
• SoundManager.LoadBanksFromModFolderOrZip(module) loads all soundbanks from your mod's folder/zip. You can use it in your module like that: this.LoadBanksFromModFolderOrZip()
• SoundManager.LoadBankFromModProject(path) loads a soundbank with the path of path (again, doesn't need the .bnk at the end) from your mod's visual studio project. The bank file NEEDS to be an Embedded Resource, OTHERWISE, IT WILL NOT LOAD. You can use it in your module like that: SoundManager.LoadBankFromModProject("path to your soundbank file in your project here")
• SoundManager.LoadBanksFromModProject() loads all soundbanks from your mod's visual studio project. Again, the bank files NEED to be Embedded Resources, OTHERWISE, THEY WILL NOT LOAD. You can use it in your module like that: SoundManager.LoadBanksFromModProject()

If you have a custom event that stops a certain sound/music you can register it so other "global" stop audio events stop that custom sound as well.
You can do it like this: SoundManager.RegisterStopEvent("name of your stop audio event here", (optional) stopEventTypes). You can add the optional stopEventTypes if you want it to be stopped by "global" stop audio events other than the universal "Stop_SND_all". Example: SoundManager.RegisterStopEvent("name of your stop audio event here", StopEventType.Music (it will be stopped by "Stop_MUS_All"), StopEventType.Weapon (it will be stopped by "Stop_WPN_All"))

You can add custom switches to switch groups with SoundAPI. If you don't know what switch groups are, they are basically groups of switches. You can set a switch for a certain object and basically that will change certain sounds played by that object. There are various switch groups, like "WPN_Guns" (used by guns to have unique sounds), "CHR_Enemy" (used by enemies to have unique sounds). Examples of switches for "WPN_Guns": "Baseball" (used by casey), "Magnum" (used by magnum). Examples of switches for "CHR_Enemy": "Bullet_Bat" (used by bullat), "Tarnisher" (used by tarnisher).

Ok enough talking about switches and switch groups, now onto the point: you can add custom switches to switch groups by using SoundManager.AddCustomSwitchData(switchGroup, switchValue, originalEventName, replacementEvents)
What the arguments mean:

• switchGroup - the switch group to add the switch too.
• switchValue - the name of the custom switch.
• originalEventName - the name of the original event that will be replaced.
• replacementEvents - events that will be played in place of the original event. They can be either string (example: "Play_WPN_kthulu_blast_01") or SwitchedEvent (example: new SwitchedEvent("Play_WPN_Gun_Shot_01" (the event's name), "WPN_Guns" (the switch group), "jk47" (the switch that will temporarily be turned on to play the event))). You don't have to make a new array to add the replacement events, you can include them as individual arguments and they will all be recognised and grouped. You don't have to worry about making them all the same type (all string or all SwitchedEvent), you can mix the two types.

There's a file in the Examples folder called ExampleModule.cs. It shows how to use various SoundAPI methods and their arguments. You shouldn't add it to your project, but you can look at it when you need an example of how to use a method or it's argument.