Global -
The 161st
Meeting of the Acoustical Society of
America takes place in Seattle,
Washington at the Sheraton Seattle
Hotel later this month, May 23-27,
2011. And why is this of interest,
one may ask? Well, two of the
invited presentations/papers focus
on the Steelpan instrument.
In a May 25
session devoted to: “Musical
Acoustics: Materials in Musical
Instruments” chaired by Uwe J.
Hansen, of Indiana State University,
Department of Physics - an Invited
Paper titled Material properties of
steel in the steelpan is the
subject of interest. This paper
comes from Andrew C. Morrison,
currently a Visiting Assistant
Professor at DePaul University,
Department of Physics in Chicago.
From 2000–2005 NIU (Northern
Illinois University) was ‘home’ to
Morrison where he was a Teaching
Assistant.
The following is
the Program Abstract extract from
Morrison’s paper:
The Caribbean steelpan is one of the
most recently developed tuned
percussion instruments and has been
the subject of much scientific study
in recent years. The tuning of a
steelpan is a complex process
involving sinking the bowl of the
pan, marking the note areas, heating
the pan to relieve stress, and
hammering notes into tune.
Throughout the tuning process the
material properties of the steel
change measurably. After the pan is
tuned, it will need periodic
retuning on roughly an annual basis,
depending on how often the
instrument is played. A process of
enriching the steel with nitrogen
has been developed which increases
the surface hardness of the steel
significantly more than traditional
methods of tuning. This nitriding
process lengthens the time needed
between retuning the instrument.
Original abstract can be found
here.
On the afternoon
of the following day May 26,
Morrison partners with two other
authors for another Invited Paper in
the “Musical Acoustics and
Engineering Acoustics: Optical
Methods for Studying Musical
Instruments” session - Thomas R.
Moore, Professor of Physics, Rollins
College and CIRES (Cooperative
Institute for Research in
Environmental Sciences) student
Daniel Zietlow - for the
presentation High speed electronic
speckle pattern interferometry as a
method for studying the strike on a
steelpan. Electronic speckle
pattern interferometry or ESPI can
be used via a laser beam upon the
surface, to calculate among other
things, the stress and strain
(fatigue testing) measurement upon
particular materials.
Program abstract:
Electronic speckle pattern
interferometry (ESPI) is a useful
method for characterizing the
operating deflection shapes and
modes of vibration of musical
instruments. Using ESPI in
conjunction with a high speed
camera, capable of capturing images
at rates of several thousand frames
per second, allows for time-resolved
examinations of transient motion.
High speed ESPI movies of note
strikes of a low tenor (also called
a soprano) steelpan were acquired
while simultaneously recording the
sound of the strike. The comparison
of the time resolved interferometry
data with the analysis of the sound
recordings allows for insights into
the evolution of coupling between
note areas.
This abstract can
be found
here.
