“One of our more surprising findings was the discovery of two apparent attempts to use the HTML5 Audio API for fingerprinting.”

https://freedom-to-tinker.com/blog/englehardt/the-princeton-web-census-a-1-million-site-measurement-and-analysis-of-web-privacy/

The findings suggest that “the number of third parties that a regular user will encounter on a daily basis is relatively small.” 

“The effect is accentuated when we consider that different third parties may be owned by the same entity. All of the top 5 third parties, as well as 12 of the top 20, are Google-owned domains. In fact, Google, Facebook, and Twitter are the only third-party entities present on more than 10% of sites. ”

https://webtransparency.cs.princeton.edu/webcensus/index.html