air in brakes??

I have a 94 3.4 v6 camaro with drums on the rear and disks on the front.Whenever i push in on the brakes and let up it sounds like there is air in them.This just started recently and my brake pads still have a lot of life on them,but are starting to glaze.I dont have a soft brake pedal or any other problems other than this noise.It is really annoying and I would be very appreciative if anyone has had this problem or knows what it might be would post what they know.
Thanks in advance for any help.

Not sure what you are hearing. Air in the lines dosn't make any noise.

What does it sound like?

It sounds like air is relieving from something.It makes kind of chh sound like air is letting out of something.But it still has a stiff pedal and only does it when I let off the brakes.If I let off the brakes real slow it will not make the sound.Could it be the master cylinder making the noise.I know this isnt the best description but im not sure how else to put it.Could it have something to do with the booster.
Thanks for the help.

Your power brakes are activated by engine vacuum acting in the big round "booster" that sits between the firewall and the brake master cylinder. What you are hearing is the vacuum acting on the diaphragm that helps apply the brakes. If you think it sounds louder than it used to, it might be worth having the booster checked to insure its still working correctly. But if it wasn't working correctly, you would have noticed an increase in the pressure required to stop. The pedal would still be "firm", but you would have to press harder if the booster wasn't helping out.

The brake pedal isnt any harder than it was before but this is probably it.Since the brake pedal isnt harder than it was before what else might it be.
Thanks for the help ill check out the booster.

its definetly the booster, you need a new one.