No sound with calling from topspeaker

REPRODUCIBILITY (% or how often):
BUILD ID = OS VERSION (Settings > About product): 4.3.0.12
HARDWARE (XA2, X10, X10 II, …): x 10 II
UI LANGUAGE: engglisch
REGRESSION: (compared to previous public release: Yes, No, ?):

DESCRIPTION:

no phone audio anymore. Tried severall solutions form the forum like rebooting, kill adsprpcd
nothing works/giving results.

PRECONDITIONS:

Yesterday in around 12 I got a phonecall. Then there was still sound out of the topspeaker.
Around 16:30 another phonecall no sound from top speaker only possible to call was using the loudspeaker.
Tried to call someone no sound either from the topspeaker.

STEPS TO REPRODUCE:

EXPECTED RESULT:

working audio with topspeaker

ACTUAL RESULT:

ADDITIONAL INFORMATION:

(Please ALWAYS attach relevant data such as logs, screenshots, etc…)