Audio-Technica’s ATH-ANC3 QuietPoint™ Active Noise-Cancelling In-Ear Headphones reduce distracting background noise by 85%..
Bought a pair of these to play around with since they were on sale last week. The active cancellation is actually very good, damps the lower midrange down without smothering the top end clarity of the outside world. They cut out car rumble nicely. They are in-ears with the little rubber sealing flange. I prefer using punched -33db blue foam earplugs on my Etymotics and need to play with replacing the minimally isolating rubber seals on these for even better isolation, but the general idea of using these as active ear-plugs seems valid after last weekend's festival. They worked really, really well for lower volume acoustic music through the FOH, but can't handle the higher SPL bass and clip with audible distortion. Needs a stronger headphone amp circuit for sure, perhaps better drivers will be needed at that point too.
Before the clipping point though, the sound was the best I have ever heard using any other ear protection. In fact, I preferred the subjectively cleaner sound with the cancellation 'on' over no hearing protection at all.