I noticed the auto-playing audio too, and I think it may have caused lag in how quickly focus was given to the search field on page load. On typing my search query, the first two or so letters of what I was typing would not appear, and I think their google doodle was causing this bug. The problem went away when they changed the artwork.
Yes, I had a love affair with DDG for years but switched for good about 6 months ago. The only thing I went to Google for was a better image search with non-specific search terms. This move will prevent me from doing that any longer.
(ddg is grand btw, ive barely noticed)