I have a 2006 Nissan Altima 2.5S that has been making a metallic shh-shh noise. I've replaced the front brake pads and rotors, but the noise continues and is now becoming a distinct grinding noise.
It's difficult to tell, but it seems that the noise is coming from the front of the vehicle and when brakes are applied comes more so on the passenger side of the car. Today I noticed the noise has become louder and more of a grinding sound. The grinding sound becomes more noticable when I turn to the left, with some noise when driving straight and none when turning left.
I've linked to some recordings of the sound. They're both faint, but you can hear it better on the first one.