OK, I found a hack that works. It stops the iOS device going into standby, and shutting off audio. Not ideal, but it works.
This is for Phonegap CLI with XCode, not for Phonegap Build.
Edit Appdelegate.m in APP_FOLDER\platforms\ios\YOUR_APP_NAME\Classes\
Add the line application.idleTimerDisabled = YES; in the location below. This stops the device from going to standby when the screen is not being touched.
This is also useful for tilt based games where there is no screen contact.
#pragma mark UIApplicationDelegate implementation
* This is main kick off after the app inits, the views and Settings are setup here. (preferred - iOS4 and up)
CGRect screenBounds = [[UIScreen mainScreen] bounds];
application.idleTimerDisabled = YES;[/code:iuhfr04t]