That's an interesting term "clearing" I like it. I equate this term with a piano tuning term "beats" and try to eliminate as many "beats" in the tone to have as pure of sound as possible.
Bingo. That's exactly it. Back when I was in my "tuna" phase a while back, I remembered "clearing" timp heads in college, and decided to try that basic approach, and it has worked for me. My toms sound better than they ever have in their own right, and the diminished sympathetic vibrations was a pleasant side-effect.
Subsequently, I've found with my Tama tension watch that your head tension can vary and your pitch be the same between Trod to Trod and vice versa! Just thought you guys might find that interesting and I was wondering if you (or any of you other guys) noticed this phenomenon when you tuned timpani or any other kinda drum
I haven't cleared a timp head in years, but I've definitely noticed this phenomenon, especially on snare drum heads/hoops.