2005 w/ 60k miles auto
I hear a knock, front of car, some of the time when driving, does not seem to be speed related as sound does not change pitch much with speed. Knock goes away with a very light touch on brake pedal and typically stops for a few seconds. After driving for a while it will disappear. Is not always evident.
What could this be?
Note that the sound is not loud, just concerning.

 

Hard to tell with that description, but it could be the brake pads rattling around. Could also be a joint in the front suspension that knocks when unloaded. Lower control arm bushing to chassis or ball joint is possible too.

Get the car on a lift and check for play in the joints.