I have read in a number of places that as your ride your bike, your cog and chainring "ramp" as they get older. Basically each tooth side becomes steeper thus creating an uneven mountain shape for each tooth. However, you mentioned you replaced your chainring. With that being said, im guessing your cog may be old and thus only really "fit" with your old chainring and chain. If your cog is not worn, you may have just purchased a noisy chain. Wipperman makes a noisy chain from what I hear.

Sometimes the grinding sound can also be from dirt or sand on your chain. I gave mine a bath in WD-40 to degrease it and clean it off, then re-lubed it. It was 10x quieter after that.

Again, check the tooth shape of your cog and compare it to the shape of you new chainring. Good Luck