[willryu]

I own a pair of the ER4XR and the isolation is very good. However I get better isolation from my Ultimate Ears Reference Remastered CIEMs. 2 cents.

 

[Infoseeker]

I was hoping for some hypothesis on why this might be so. Is it because the ETY body is so much narrower than other IEMs, maybe? Less noise transmitted thru the IEM body...?

There is no special technology. It simply goes in deep in your ears and plugs things closed.

Since they use self enclosed BA drivers, they don't need air and can be fully sealed.

There won't be a new wave of technology to replace the way it plugs into your ears. They are future proof in the noise isolating sense.

 

[WilcoRoger]

I have a couple of etymotics and the klipsch x12 - with the same tips both isolate very similarly (ie darned good) Both are tiny, so you can (an must) insert them deep.