Hi, I've bought a L510B and it omits a high pitched sound which is audible up to 10 feet away.  The sound is present even when the bulb is off so I guess it is related to the wifi components.  I'm just about to return it as its unusable, I certainly couldn't use it in a bedroom and even in the front room it is distracting.

Just wondering if this is a faulty unit or whether they all do this?  I got it from amazon (£6.99 currently) and there's 3 reviews out of a few thousand that mention the high pitched noise.

It sounds like coil whine to me.  Noise is at approx 6600hz: