In my hybrid Cordova Android app targeting API 23+ I want to use a custom sound for notifications. To that end I have done the following
plugin.xml
You are accessing the sound in a subfolder in the resources
change the source of your uri to
Uri uri = Uri.parse("android.resource://" + context.getPackageName() + "/" + R.raw.siren);
For the default sound, use:
notification.defaults |= Notification.DEFAULT_SOUND;