Does exactly what it claims, but I had some issues with my pair
The sound quality and function of this piece of ear protection is great. It does exactly what it claims to do - it provides close to normal hearing at low volumes, and then protects your ears at higher volumes. However, I had some issues with my pair.
I might just have gotten a bad pair, but the two pieces were uneven in protection level and quality. One of them seemed to dampen less, and got all weird and crackly at very loud volumes, while the other one dampened more and didn't have that crackling issue. When the higher volumes stopped, the one that dampened less would be back at normal hearing much quicker than the other, resulting in a very uncomfortable feeling where it feels like you have an air pocket or something in one ear. It got pretty uncomfortable after a while, so I decided to send them back. Might just have been a bad pair, who knows. Still loved the functionality of these ear protectors, but something just wasn't quite right with mine. I tried everything to rule out what the problem could be, but nothing seemed to work - neither with nor without batteries, the problem wouldn't go away. One ear was dampening more than the other. Terribly frustrating.
It should also be mentioned that these don't handle extreme sound volumes very well. They simply don't reduce the sound level enough to provide enough protection. Also, they have issues with drums. The many different frequencies and sound volumes going on at the same time behind or in front of a drumkit make them go crazy. If you're a drummer and nothing else, don't get these. I got them since I play the saxophone too, and in those settings, they offered enough protection.
Those ear protections are the best I never tried: because of an accident (ear injury), I must play always with plugs. With standard ones, balance was difficult, I heard too much my sound coming by inside of my head, and there was no easy adaptation to the real level of sound: sound reduction was too heavy in pianissimo passages or too weak in fortissimo moments (no suitable for symphonic). But these ones, with the electronic filtration are much better, really adaptative and reactive to the actual sound level. In pianissimo time, you can hear every little details, and the conductor speaking, and in case of brutal percussion or brass intervention, the protection is immediate. Many different shapes an materials plugs are furnished with this item, to fit everybody's ears. As a trumpet player, I can work only with foam plugs and can not play with silicon or hard material, because emissions in high register cause some static wave between the plug and tympanum, so the Etymotic foam adaptators are really welcome !