In the iOS 8 web view, HTML5 audio does not play, even in a user input event. (Safari on iOS requires a user gesture for HTML5 audio playback to begin; this does not work in the web view.) The Web Audio API works, but HTML5 audio does not, even if routed through the Web Audio API with createMediaElementSource(). This is important so apps using PhoneGap can play audio.
Do you have a sample test page that shows the issue?
This may have been fixed by http://trac.webkit.org/changeset/169867, but we need an example app to make certain.
To repro, point a web view at this URL: http://www.scirra.com/labs/spaceblaster/ In Safari, it should play music on both the title screen and in-game (after a touch). In the web view on iOS 8 beta 2, I never hear any music, although I hear sound effects (which are played with the Web Audio API instead of HTML5 audio).
Additional minimal repro: https://dl.dropboxusercontent.com/u/15217362/webviewaudiotest.zip That should be directly uploadable to PhoneGap Build. iOS doesn't show the buttons properly: the top button plays HTML5 audio with a local (package) source, and the bottom with a HTTP server source. Neither works.
Appears fixed in iOS 8 beta 3. Thanks!