Warbling piano wire

[Ron Nossaman]

This is a slightly updated copy of my August 1995 newsletter article that
sort of fits in the category.

FWIW


'The beat goes on'
  
 Hi ladies, gents,and any other alternative genders being represented by
this assembled gathering. Today I would like to discuss something that I
have noticed for many years but haven't seen or heard any discussion on.
It's time that changed. The session starts with me going into a church
sanctuary to tune the piano (most likely on an emergency basis). My
instructions are to tune the piano to the organ. So far, I'm already not
overly thrilled by this provision of employment (four star emergency status
alone should be enough for anyone), but I struggle past the electric
guitars, drum machines and keyboards and through the fifty furlong tangle of
power cords to get to the piano. Arriving at the piano, I dig out my tuning
implementia and lay it on whatever part of the instrument is flat enough to
serve as a shelf, grab my fork, and start hacking a trail through the
electrical jungle in the general direction of the organ. 
  
It occurs to me that I should radio my position back to camp so they would
know where to start looking for the body if I were not to make it back, but
I had already lost sight of the bivouac . 
  
Arriving at what I took to be the organ, I read the name on the front. Not a
Hammond, gotta check it. I sat down among the crumpled kleenexes, reams of
music, and mountains of hymnals to try to figure out how to fire the sucker
up.  I found the power switch and, rocking the volume pedal back all the
way, switched it on. A whole lot of lights came on at once accompanied by a
low evil hum. Fire in the hole, I thought, at least I won't have to go back
for coal!  Yup, that's an organ, probably given to them by an organ donor.
Cheered by the relief of not having to stoke for the tuning, I began to
explore the stop setup.  I've always been curious as to how one was to tune
a piano to an organ with every tremolo, vibrato, vox, quiver, quaver and
quake function money can buy engaged, locked in semi-permanent mode at the
console. Maybe some day I'll do it and let them try to convince ME that the
piano's not in tune. I indulged that little fantasy a bit as I shut down all
but the cleanest stop I could find that worked. Taking a deep breath, I
struck the fork. Impossible! It's dead on pitch.  Well, anyway, that
particular note is and that's good enough for me. I checked around the
temperament a bit satisfying myself that this was worth the trouble and ,
wedging my key down with a rubber mute, started back toward on the now
fairly cleared trail to the piano. I'm walking along thinking how
uncharacteristically lucky I was this time in not having to try to explain
to the secretary, Pastor, Custodian and passing UPS man about the
inadvisability of knocking a piano out of tune to accommodate a neglected
organ just because they were too disorganized to get the organ tuned since
Edison plugged the thing in. Imparting this information is easy enough to
do, it's just tough to do it gently enough that they don't send you to their
competition in a fit of pique. Anyway, such were my thoughts when I became
aware of a strong beat in the organ note. Alarmed, I stopped. So did the
beat. When I started up again the beat did too! Wow! Too cool. What makes it
do that? Thinking about it while tuning (you have to come up with SOMETHING
entertaining, after all) I decided it was a Doppler effect of some sort, but
what made it work? An approaching siren lowers in pitch abruptly as it
passes you just like radar modulation frequency shifts as it bounces off
moving objects. This is how meteorologists can see high winds in storm cells
and Smokey nails you from a moving unmarked revenue patrol wagon. If this
was the mechanism, wouldn't the pitch get lower as you walked away and rise
as you approached? Well, it does, but not a lot from the amount of speed you
can work up flailing through Patch Cord National Monument across the length
of the platform.  Besides, the noise of falling MIDI enhancements tends to
drown out the critical observations and obfuscate the results. I really hate
it when my results get obfuscated, so I try not to do too many high speed
Doppler experiments among and through expensive electronics. This is
interesting and all that, but it still doesn't quite explain the beat. I
decided to take the experiment home where I had some traveling room. I
shouldn't have to tell you this, but I didn't drag their organ home to test
the principal. Besides, that wasn't the stop I chose anyway. I have my
father in law's old Accu Fork, and it seemed like a reasonable substitute. 
  
The first thing I did back home was try to reproduce the results I got in
the church. I turned on the Accu-Fork, sat it on a handy flat spot and
walked away.  Wa-wa-wa-wa. So far so good. Coming, going, same thing.
Wa-wa-wa-wa. About then my kids swarmed through and stopped to watch. I've
always suspected that they are secretly taking notes for a possible future
competence hearing when they do this, but I decided to try to lure them into
a little live scientific endeavor just on principal. I might need some
testimony ammunition of my own some day. They thought it looked pretty
harmless and considerably more entertaining than most of my forays into
basic research, or beatings, so they agreed to help. When I explained what I
was doing and demonstrated the beat, they were hooked. I tried carrying it
around the room. Beats. I waved it around without walking. Beats. We decided
to go outside and try it. Holding it, I walked around the yard. NO BEATS! I
waved it around. No beats. Going back inside, beats appeared as I approached
the building. We tried the walking around trick, followed by the under the
paddle fan trick, followed by the holding the pitch source while someone
else walks around trick. This last one is like the walking toward the
building trick in that you get an echo beat as someone moves toward you even
though you are stationary. That, we decided was the answer. It's an echo
effect. The beat rate increases with the speed of convergence or divergence,
not distance. The reason would be that the Doppler shift changes the
frequency of the echo off a moving object so that it no longer matches that
of the generator. The greater the difference, the faster the beat. That's
why there isn't a detectable beat outside on the lawn. There aren't any
sound reflective surfaces close enough to generate a strong enough echo to
produce a noticeable beat. Ha! That would appear to wrap up the case of the
beating organ, but does it? If anyone has any counter logic or experiments ,
I'd like to see the show. 

 Ron N