On my Sony Xperia M2, running Android 4.4.2,, two or three times a day, the sound volume of the ringtone and notification alert drops to a barely audible level. When this happens, calls can be missed as the ringing may not be heard.
The volume setting does not change, just the volume itself. If the phone is powered off and back on, then the volume is restored to normal. No earphones / headset is connected to the phone at any time, either by pluggin in or by bluetooth.
It is possible that the volume drop occurs because the ringtone is being diverted to the internal, i.e. in-call, speaker.
I am trying to work through all the installed apps to see if I can isolate one which is hijacking the sound but without success. Is there a known issue here? A known faulty app?