I attached the audio. Between 1:42 and 1:56 you can hear a pretty good run, from acceleration, to the knocking sound, to deceleration when the sound fades. The only way to reliably reproduce the noise is to let off the accelerator just a bit. If I let all the way off or accelerate the noise goes away or reduces to a soft clicking. I will pull the wheel off and check the clearance on the brake dust cover tomorrow.
The audio didn’t seem to attach, so here is a link:
[audio src="https://www.dropbox.com/s/qwf0m1j8bbsgheb/Front%20end%20noise.wav" /]