Whining/Whistle Sound

2000 S10 Blazer 2 wheel drive 

When accelerating the whining sound is high and then seems decrees when slowing down. The sound also happens when in park while pressing down the gas peddle.   Any ideas?   I’m thinking vacuum leak but I am not a mechanic?

Can you give a guess as to where the whinning sound seems to be coming from???

First thing I think when people say whining is Alternator.  But Whistling would sound more like an air leak somewhere.

It may possibly be the brake booster.
My booster is making a rattling sound that I hear through the dashboard. While researching the problem I ran across many owners who are hearing a whining or whistling sound from the booster.

mine whirs slightly but i don't mind it it seems to be coming from the front of the engine like a belt or pulley but hey could be my alternator cause its going out.

EDIT also I have the rattle from the brake booster which is annoying! any solution?

It makes sence too.
I was also told that the belt tensioner may be a cause of a whining sound. It would be a rapid sound that would change during different driving canditions. The booster may remain constant with the vacume.

As for fixing the rattling. You really can't. You have to change the booster or the valves may fail soon and leave you with no brake boost. This seems to be a problem for many of the GM SUVs and trucks. The failure occures long enough after the original warranty and since it does not trigger a code the extended warranty companies don't cover it.

meh ill let both go no sence in fixing what isn't broken 

ok i feel pretty good cause now heres a problem i think i can use my limited mechanical knowledge and experience to help fix. i'm having the same problem with my truck. the sound is coming through my speakers. from what i've been able to gather it's feedback or somesuch thing and it's being caused by the alternator. so now i get to spend $70 on a new alternator. my problem aside that should be your solution. also check your battery charge guage meterie thingie (thats a technical term by the way) mine is spending most of the time in the red but if yours is up then theres some corroborating evidence.
good luck

I also had a whining sound which was coming from the front of the car. I had also noticed my interior lights dimming on and off when coming to stops and when using the brakes. I tested the alternator and it was going bad. Replaced it and the whining problem went away.

well my alternator is fine for the most part but every so often, it wont charge at idle. 

I also have a whining noise that occured when my truck is between 2500-3500 RPM then it will shift. It is a noise that almost sounds like a supercharger. Any ideas?