brakes

I had the master cylinder replaced and when they were bleeding the brakes they needed to replace a brakeline cost me 500 bucks. Now there is still a noise on the left front of the car like a swooshing. when i apply the brakes it stops. apply the gas hissiing or swishing. I was told it may be the power brakes booster.

Thoughts idea's please help...............olds 88, 1994 140, 000 km on it