front end whine

[Andrei Kogan <abk@phy.duke.edu>]

Hello,

my 4k has developed a curious noise which seems to be coming from the left
fron wheel. It is a barely audible high-pitch whining which strangely
disappears if I lightly depress the brake pedal. In fact, this is how I
noticed it --- otherwise it is not readily distinguishable from the wind
noise.

It doesn't change with load and it sounds the same when going through
curves. Could this be a sign of a dying wheel bearing? I am surprised that
it responds to the brakes, even a slightest push on the pedal makes the
noise disappear, before  any noticeable braking takes effect. Any ideas? 

I tried to spray the brake caliper and it didn't make a difference. I
haven't had a check to remove the wheels and look at it carefully, I will
do so tomorrow.