Loose Ribs

[Larry Trischetta]

Hi Clark,
If I understand you correctly, the buzzing is vibrating at the same
frequency of C#5 and/or D5 and that would make sense. Buzzes from two
materials hitting or vibrating against each other are set in motion by
physical vibrations i.e. transference of energy along a path, whether it is
a solid (wood) or a gas (air). With lower frequencies, the wavelengths are
very long... a few feet, and as the frequencies rise, the wavelengths get
shorter, a few inches or less. The longer wavelengths from the source
frequencies just move the two materials together (rib and SB) but the rib
and SB don't create long wavelengths (too much energy required). So you then
only hear random vibrations of the materials, not at a given pitch.  But
when the rib and SB are vibrating at higher frequencies (shorter
wavelengths) they now have enough energy to recreate the short wavelengths
and they are transferred through the air. Then you hear the rib and SB
vibrating and producing very short and audible frequencies. The natural
resonant frequency of the material picking up the vibration will determine
whether or not it will "match" the source and vibrate accordingly,
therefore, only materials with the same resonant frequency as the source
frequency will vibrate.

(As I was writing this, I realized that I understand what's happening MUCH
more clearly than I can explain it... maybe someone can explain it better
than I can). The sound on the recording of the buzzes simulates the idea
behind what makes a Kazoo sound "musical".

Larry Trischetta

-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Clark Sprague
Sent: Thursday, February 07, 2008 11:38 PM
To: Pianotech List
Subject: Loose Ribs

Hi, all.  I was trying to tune a Shoninger spinet tonight (what a horrible 
thing), and when I got to C#5, and to a lesser extent, D5, I heard the 
weirdest sounds.  I knew that the thing had loose ribs, and they were 
buzzing most of the way up the piano, but at that point, they began to buzz 
"harmonically".  I have never heard this before.
    I have attached a recording made on my Dell pocket PC, on which I run 
Tunelab.  It is a .wav file, and can be opened with Windows Media Player.  I

turned the volume up, and it comes through clearly.  And it is different the

second time I hit C#, from the first time.
    Anyone heard this kind of vibe coming from loose ribs before?
Clark A. Sprague, RPT