Yes - I agree with what others have said .
Although I am using Grid 2019 , issue seems the same . Like digital stammering - like you are trying to play a cd with lots of scratches.
Forum on steam suggests to change the bitrate on sounds settings -> additional settings -> advanced .
This has not worked for me .
Generally , sound is bearable on a qualifying lap with just myself on track . But add in the other cars and it soon deteriorates .
It may be to do with the mixing of sounds .