I would say that there is no sibilance when used with a decent recording. I have not heard any sibilance even with ATrac - type R. And treble is crystal clear when applied to Digital Recordings.
We'll agree to disagree on the sibilance then
You will need to wear the correct plugs that come with these so that there is no sound leakage. If you have the correct plugs then most background noise will be cancelled out.
You will get blustery noise's with any in-ear or headphones if you use them in windy conditions.
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I agree they get tangled up easily and they need running in too. But for the money nothing at the £25 priced point for that style of headphone/earphone beats them.
Audition - you wont be dissapointed.