Sympathetic Vibrations

This is a second attempt to post to the list in response to posts in
January about sympathetic vibrations (I'm trying to catch up with a
lot of old tuning posts):

>> I believe that sympathetic strings do indeed work by transferring
>> the energy through the air. As a simple experiment, sing into a string
>> on a guitar, and you can easily set the string to vibrating
>> (sympathetically) with your voice.

> In that particular case I'm almost certain that what gets the guitar
>string to vibrate is the sound waves from your voice vibrating the
>soundboard, which vibrates the strings. FAR less, I believe you'll find is
>a result of the air directly exciting the strings themselves.

The justly-tuned aluminum tubes of my Woodstock Gamelan will vibrate
sympathetically whenever a pitch is soundeded at the same frequency as
one or more of them. This works not only when pitches are played on the
flute or sung, but even when I cough! Coughing gets quite a few of the
tubes to sound, and sometimes even when the cough is in a different room!
There is no sounding board on the "gamelan," so this phenomenon is
definitely transmitted through the air directly to the tubes.

An interesting feature of sympathetic vibrations in strings or tubes is
that they lack the characteristic attack, and often have timbres closer
to sine waves than the timbres produced by "normal" playing techniques,
such as struck, plucked or bowed.

Lydia Ayers

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