The volume level for sound effects when riding on cobbles and near waterfalls is far, far louder than any other sounds in Zwift to the point where I’d consider it a defect. I understand the need for it to stand out a bit, but the current setup is crazy loud.
This is a problem for everyone trying not to disturb their surroundings, trying to listen to music, using headphones, etc. This is also a common complaint for Youtube/Twitch streamers - the people promoting Zwift. It is bad both on worlds with short cobble sections and worlds like Paris with constant cobbles. The sound is simply far overwhelming anything else going on.