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2007 Civic Buzzing/Whirring Noise From Behind Dash

On a 2 hour drive this evening near the last 15 minutes of it I noticed a strange noise coming from behind the dash from what seemed like the driver side. It is difficult to describe this noise besides saying it sounded exactly to me like it sounds like when a computer fan is going bad. That grinding/buzzing/whirring noise is what I heard. The frequency of this noise occuring is random, I was unable to find a specific pattern of accessories being on to make it start.

On the way home I started testing some things, here is what I know so far. AC was off, fan was also off, noise occurred regardless of Cruise Control. Pitch and frequency remained the same regardless of speed. Now here is the key clue, when the sound would start up and get going steady if I pressed on the brake it would disappear for several minutes (sometimes as long as 15-20) before returning again. This brake thing seemed to work 100% of the time, everytime it would make the noise stop. It also seemed like if I just lightly pressed on the pedal, not quite enough to slow the car down the noise would go away and then if I let off the brake pedal it would come right back. It definitely needed to have the brakes activate for the noise to stop.

Now the noise was very focused, it sounded to be coming from within the engine compartment roughly in front of the driver seat. This would make some sense with the whole braking thing since right there if you open the hood against the back wall is the master cylinder for the brakes. Is the master cylinder even capable of making noises like this?