Mine have been doing this for months now - it is only the left earbud and it drives me INSANE. Every time I move I hear the swoosh tone. I happened to be looking at the app one day when it was doing this and noticed that the ambient sound was going on and off. I seriously can not take it any more. This is my second pair (I had the first gen) and I love them, but I can't go on like this. I've been looking at other models and brands because nothing I do seems to fix this issue. I've reset a million times. This is really unfortunate.
I'm having the exact same problem. The right earbud's volume is attenuated significantly. Also, when I open my mouth to yawn or move my head side to side, I get the "WOONG" sound. Frustrated with these earbuds.