I think that there may be a sound bug with 8.1.2. I had problems, noted elsewhere here, with sound and the 8.1.2 upgrade and I have since noticed a loss of sound at times, including just now, for no apparent reason. This is most noticeable (to me) by the lack of the battery charging sound when I connect the mains charger. (So, with the most recent problem, I checked for sound from an internet radio station I access at times and clicking when I type- both silent. Previously they had been working.)
My cure (at present) is to power off completely and then power up again when sound returns in my 'expected areas'. (I have not adjusted anything else.)