Is it normal, that sounds when you right click on building or voices when you right click on citizen are repeating constantly?

So far my solution was to right click on something not so annoying or on water/ground (this seems not to repeat).

Another thng is that sometimes the narrates in campaing stops and repeat from beginning.

And the sound of the popu-up event messages (´working colloseum, hippodrome, god effects) is not respecting the soud settings and play at 100% which is extremely irritating when that heppens...

Are these usual C3 issues or can this be perhaps result of drivers/OS and can it be fixed?

I've heard about the repeating sound issue, but I've never suffered that or any of the other problems you mention here. I'm playing on a 64 bit win7 system.

I have the same problem, is not only the sound, but the music too. It's a minor problem, but a problem nevertheless.
One way i could solve it is by going to the game folder, right click in the game (C3.exe) and in the compatibility tab run it for windows vista, and check the "Run this program as an administrator" box.
Either way, when i try to launch it from the galaxy client it doesn't work, only by opening "C3.exe" directly.
Hope this helps, regards.

see if this solves your problem (it did work for me):

https://www.gog.com/forum/caesar_series/sound_keeps_repeating/post12