I first noticed intermittent sounds when walking around, but finally figured it was the direction I was looking that made the difference. While descending a long ladder, I took a moment to look up instead of down as I always do, and the clunk-clunk "Ladder" sound stopped. When I looked back down it started again. It appears to effect the terrain sounds also ie; walking on gravel, sand, dirt, etc. I have found no way to resolve this issue so have chosen to list it as a "Bug".