Update August 19, 2016:
The folks at EasyList aren't able to reproduce this. Since they can't hear these ads, they're unable to figure out a way to block them. For now, try the filter below anyway. It's still working for some people at least some of the time.
Update August 12, 2016:
We're getting reports that the filter below no longer blocks these audio ads. We have reported this to EasyList and are waiting for an update.
If you're suddenly hearing audio ads on Tumblr.com, this post on the EasyList forum provides a filter that should block them.
- Click the AdBlock button and select Options, then click the CUSTOMIZE tab.
- Click Edit to open the custom filters box.
- Paste the filter below exactly as given.
- Click Save.
- Reload the page you're trying to view.
Copy this filter: