I'm sure that by now you've noticed that basically all of the sound-bugs have been fixed with the latest update of the TruckersMP client. More information about the exact changes and fixes can be found here:
Due to the fact this would've belonged in the Help-Section (not your fault though this time) and that the bugs listed by you have now been fixed, this topic will now be locked and archived. If you have any questions or concerns, do not hesitate to get in contact with me :)!
TruckersMP GM + FM