[Harp-L] Comb Material Experiment

[David Wilson]

I'm so stoked to see this topic come up again!!!  I was standing on the sidelines eating popcorn during the great comb material debates of decades past, and always enjoyed the fireworks that inevitably followed.  I will not be at SPAH this year, but I hope this experiment will happen.

About methodology, my recommendations would be:


  1.
Don't use a human player for the comb testing - too many potentially confounding variables there.

  2.
Also don't use a bellows as that does not allow for a note to be held long enough for listeners to discern the subtle differences in tonal quality.

  3.
I'd recommend finding a way to get a hose/tube or other apparatus to continuously blow/draw air through a single hole at constant air pressure/vacuum pressure.  With this setup, you could play/record long-ish samples for each comb material (say, 15 seconds each) to allow the listener to listen carefully and hone in on any differences in tonal quality.  Also, you probably want to select a lower hole on the harp that would have better potential to get the comb material resonating (if there is such an effect).  I think both a 3-blow and 2-draw would be optimal as it would give you the same note, and this would allow for the testing to detect any differences in comb material tone between blow notes and draw notes.  Also, to calibrate the volume level created by the testing apparatus, I would recommend setting up a sound meter at the testing location; having a human harp player play long tones on the test harmonica on the test holes; record the decibel readings for those long tones; then adjust the pressure/vacuum of the comb testing apparatus to approximately match the volume created by the human player.

Good luck!!