I have noticed a sound that's like air being let out of a tire, when I'm driving my car. The sound seems to stop when I either put my foot on the brake or sometimes when I put my foot on the accelerator. Separately sometimes when I take my foot off the brake and I'm coasting, I hear a sound that's a cross between a high pitched ping and squeal. It's not terribly loud but it is loud enough to hear. This happens from time to time. Any help would be appreciated.