Hi Jake. I was trolling youtube not so long ago and watched a guy doing a instructional video and he kept placing something in his mouth each time he went to play. Whatever it was it was small and seemed to sit in the front of his mouth. I will try and find it again and post. Very curious and i wonder if it was for a particular sound effect?
No I didn’t hear it. From what I took from it was it was a soft piece of metal fitted to be placed inside the mouthpiece. It would roughen up the sound make it grittier I guess. It seemed like it would vibrate inside the mouthpiece that would give the harshness. Maybe I will go back and ask him to demo it for me.