[Harp-L] Comb Material Experiment

[meagher@xxxxx]

Thanks David! I have already observed - not surprisingly - that there are
some VERY strong opinions on the matter. The complexity of designing the
experiment is not lost on me, and it seems that no matter WHAT I do, certain
people will reject the conclusion if it doesn't match their preconceptions.
Not really my concern, but I'm eyes wide open on that. 

 

I have gone back and forth on the human player vs. bellows topic, and I
think your suggestion of another apparatus - to isolate things absolutely as
much as possible - is clever. That may be the right way to go! 

 

I appreciate your thoughts here, and if you don't mind, I'd love to chat
further as I go about the design process, get your perspective on things. 

 

Evan 

 

From: David Wilson <harpoon_man at xxxxx> 
Sent: Monday, February 24, 2025 10:05 AM
To: harp-l at xxxxx; meagher at xxxxx
Subject: Re: Comb Material Experiment

 

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!!