I have experienced allot of audio issue's regarding volume.
Meaning that when i set the volume of a soundfx "lower" then its normal volume, the sound first plays full and then drops down.
In my game (a mini strategy game on the Iphon4) i have allot of gunsounds and explosions running at the same time.
So u can understand that i need a perfect balance in the audio.
When using the CocoonJS Launcher, the volume(drop)issue is not resolved, mainly because (what i have read in other posts)the audio api for html5 is just not perfect yet.
So i came to the conclusion to delete all my volume settings within the game project.
And then try running it again in CocoonJS.
This time the audio worked perfectly..
I still need to manage the audio differences (as written bellow) but at least the audio volume does not drop after first hearing a full peak.
So the tip here is to just open your favorite wave-file editor and "process" your soundfx with the volume "gain" u intend to use in the game.
Then import the file into Construct2 and use it without any volume settings.
It may take u a while to orchistrate the perfect balance but its worth it.
And best of all!!!
I got 7 FPS back when not using the set volume option.
So my game runs even better.
Just a Tip.
Maybe its usefull to u