The noise is most lilkely coming from the brake booster. It is what provides power assist to the brakes and is run by engine vacuum. If it is bad or leaking, you will hear the sound you described.
You can test it with a vacuum tester. Basically, you create vacuum in the unit and see if it can maintain the pressure. If it drops, then replace the it.
Also I have seen the pedal carriage break causing both pedal to be pushed when just one is. The instructions to change it are in the diagrams below. Let me know if you have other questions.
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Wednesday, April 14th, 2021 AT 10:37 AM