High pitched sound when releasing the brake

Out of curiosity, does anyone notice a faint, yet high-pitched sound - almost like a beep - when releasing the brakes?

It's not the buzzing of the brake accumulator pump.

Here's how I duplicate it:

Park somewhere, put parking brake on, put car in neutral, press firmly on brake pedal. Now, when I release the pedal, I hear a high pitched sound that lasts no more then a second.

I took it in to the dealer to look at and the mechanic said it was pressure releasing or something like that...

Just making sure I'm not the only one that hears it...

 

No, I don't think it's related to the accumulator pump unless that tsb is referring to a separate noise. Since I also hear the normal buzzing of the accumulator pump after a few brake presses.

I haven't been able to get any sort of sound recording from anyone that is more familiar with the issue. I wouldn't describe the sound a seal barking though.

I'd say this high pitched sound is much more frequent (happens like every release of the brake recently) then the brake accumulator pump going on.