[Lowboy]

Well, I was playing my melodicas tonight and started to think about this thread. Then I remembered I have a Marine Band harp in the key of C. So I played some notes on the harp and ran my fingers in various ways over the outlet slots on the back, sometimes covering most of the slot. Wow, it produces a huge variation in tonality and harmonic content; much like I get by choking the back of my melodicas. And much like harp players get by cupping and uncupping their harps. Then I started looking around on YouTube to watch other harp players. I did not see one of them doing what Sonny Boy did, at least not yet anyway.

So based on all of that, I would suggest Sonny Boy is manipulating the sound. You can’t really put the visual and sound manipulation together because the timbre and harmonics never stop changing as he plays so expressively. But, I would also suggest, as Kevin points out, he is probably using this unorthodox method of sound manipulation for “show.”

I would speculate that this technique (direct blocking of the outlet slots) is not commonplace among harp players because they can get more variation in sound by cupping and uncupping the instrument. Cupping/uncupping basically produces the same changes in harmonic content and timbre as blocking the outlet slots. But cupping/uncupping provides more expressiveness.

Lowboy