1999 Subaru Forester: Is this a pressure relief valve?

I noticed something while riding as a passenger in my 1999 Subaru Forester lately. I was riding in the front passenger seat with the window down, and noticed a strange “spritzing” noise coming from the passenger side front of the vehicle. The sound is very brief, about a second in duration. I heard this repeat several times as we went down the road, and decided to time it. It turns out that this sound occurs exactly every 33 seconds while the car is in gear going down the road! It sounds like a pressure relief valve going off…but what could it be? I have no idea…maybe somebody knows…

Was the A/C on? Could it be the compressor cycling on and off?

Nope, not anything to do with the air conditioner! You won’t believe ho this puzzled me until I finally figured it out! The alternator belt was making the noise in that cycle. I guess the belt has a certain spot in it that when it gets to that place it makes the noise that sounds like a spfffff when it comes around! I tightened the belt and the noise went away! Jeeze that’d make a good puzzler!