Re: OT:Singing bowl measurements

[Matthias Grob <matthias@grob.org>]

>My son Eli and I studied the output of his singing bowl with a
>spectrogram.

great! Thank you Bret and Eli!

>I overstated the bowls size in my earlier post.  It is 117 mm outside
>diameter (about 4 9/16"), about 63mm high, rounded, and about 2mm thick
>at the top edge.
>
>The spectrogram allows us to see, in a scrolling chart, over time in
>the horizontal axis, the frequency components in the vertical axis,
>with the amplitude of each component indicated by shading.  The lowest
>tone recorded was about 390 hz, approximately a G.  The first overtone
>was at about 1070 hz, the next at about 1950 hz.  These measurements
>are +/5.4 hz with the scale and tool used.

hm,,, for me overtones are multiples...

>We attempted to match the tone by ear, to a synth patch that had
>fundamental and 2 harmonics (390hz,1170hz, 1950hz , fund, 3rd and 5th
>harmonics).  We compared the audibly matched synth tone to the bowls
>tone in the spectrogram.  The fundamentals matched in frequency.  What
>we heard as tones in the bowl, matched what we heard on a minimal
>overtone synth oscillator.  These sounds differ by the first overtone
>frequency.  The synth has 1170hz (3rd harmonic) and the bowl has about
>1070hz which is about 2.74 times the fundamental (390hz).

may this mean that 390 is not the fundamental?
Then again, I cannot find a fundamental with overtones 390 and 1070...
I can easily imagine several fundamentals, so 390 and 1070 could be 
independent vibrations (axial-radial, for esample).
But why is the third harmonic 1170 present? Did the 1070 "eat" it?

More even I wonder now how they select the bowls: Could yours be a 
good one because the 5th harmonic appears cleanly... or a cheap one 
because the 3rd does not?  :-)

>We found no illusion between perceived pitch, and measure pitch with
>the 2 types of sounds.  The beats in the rubbed bowl do change the
>character of the sound dramatically, however.

I am not sure I understand what the beating sounds like...
Is it a subharmonic maybe?
Interference between the stick movement and some fundamental?


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