UPDATE: This post is partially irrelevant. As of Version 10.4.4 disabling (Muting) Roles in the Timeline Index now disables them in exports as well. Consistency! 🙂 But if you were wondering what it used to work like in the olden days… Read on….
As this is a topic that seems to cause some confusion, I thought I’d write a little post about it. It confuses me sometimes too, so this post is also for me… to refer to when my brain freezes up. I’ve included the obligatory video below. It’s too long for a Gif-Tip™, but I’ve tried to be uncharacteristically concise. 🙂
So… there are 3 main ways to mute or disable audio in FCP X, all of which have different results. If you know what’s what, it’ll make your life easier, particularly when exporting movies, audio, or fcpxml to send to translation apps such as X2Pro. Here they is:
Timeline Index
-Turning off the Role in the Timeline Index mutes it for playback, but it will still play if and when you export the Project with a comp mix. You can of course exclude Roles if you export a multitrack Quicktime (for stems, mix minus etc). **Update… as with the Inspector, disabled Roles will not appear in fcpxml exports.
Timeline
-Disabling (Muting) an audio clip or component (multichannel track) in the Timeline (V key) will do what you’d expect, you won’t hear it, and it won’t play in an export. However, it will be shown as enabled in an fcpxml export, and will appear, muted, in anything that uses that xml for translation.
Inspector
-Disabling a clip or component in the Inspector makes it inaudible during Playback and export, it will not be shown in the timeline, and the fcpxml will indicate that it is disabled and it shouldn’t be included in any translations. **There is a preference in X2Pro (and other translation apps) that lets you choose to exclude or include disabled items the AAF.
With multichannel clips, the only way to not have all the components appear in an AAF, is to disable individual components in the Inspector. If you only want CH-1 & 3, you need to uncheck all the others.
** In X2Pro’s preferences, you can choose whether you want disabled clips/components to excluded, or included but muted. Make sure you set it for what you want!
For an exciting moving pictorial version of this post, see below. Hope it helps!
Final Cut Pro X Babbling 
My question is in FCP X 10.3.2 in the audio inspector you have two check boxes for a componant. One check box seems to darken the audio clip, but you can still scrub it and here the audio, and the other will remove from view. What exactly is it doing?