The Steelpan Vibrations Team thanks all the volunteers who contributed to this project since we have gotten many great classifications so far. We believe that you should get to know what this project is and how it came to be, so you can understand more of what we are doing.
WHAT IS THE STEELPAN?
The steelpan originated in Trinidad and Tobago and is essentially a 55-gallon barrel that was carefully hammered on the bottom for tuning. The unique nature of the Steelpan comes from the vibrations of different notes that are all coupled together since the notes are all embedded in the same piece of steel.
While we have a limited understanding of this vibrational coupling, we do know how the individual notes behave.
To understand how to interpret images made by electronic speckle pattern interferometry you can look for the concentric rings which indicate where the steelpan is vibrating. These sets of concentric rings are also known as antinode regions. The numbers or rings, or fringes, measures the amplitude of the note’s displacement. The first image below shows a single note vibrating at the frequency of its first resonance (the lowest frequency resonance.) on a tenor steelpan.
In the image above, we see the same note in its second resonance. This resonance has two antinode regions, separated by a nodal line running between them as seen in the image above.
HOW THIS PROJECT CAME TO BE
It has been long suspected in the musical acoustics community that the sound of the steelpan has a time-dependent nature related to the transfer of energy between different components of the sound spectrum. It is not well understood how it works and historically has not been easy to observe the motion of the steelpan in the short time after a strike has occurred. In 2009, the Physics Department at Rollins College acquired a high-speed camera to use with their electronic speckle pattern interferometry system. Professor Morrison was intrigued by this and wanted to see if they would help him make those observations. When he went there, they were fortunate enough to help with his measurements.
The Caribbean Steelpans were chosen because Professor Morrison liked how it was a recently invented tuned instrument which is prominently used in the world. He also enjoys its deceptively complex mechanical system–meaning it looks simple enough as it is just a bunch of notes hammered into the bottom of an oil barrel, but the complexity of its rich sound grows deeper it is studied.
Through getting this research off the ground, there have been various failures. Such an early failure was that Professor Morrison looked exclusively at the first 100 or 200 frames after the mallet strike happens. He thought that was enough to analyze it, but he realized that he was looking for what happens in the first 2000 frames and would need a different approach. On the flip side, some successes were in the Summer of 2017 where the previous research team helped Professor Morrison develop this project into an official Zooniverse project. They chose Zooniverse since it was the best platform for a crowd-sourced volunteer to classify and analyze data that cannot be easily processed by software. A python code was written and developed last year, and they learned enough of the project to present their work to the acoustical society of America in December of 2017.
WHAT WE NEED
What we want to know is how do the vibrations propagate in different areas of the steelpan’s surface? It leads to a better understanding of how coupling vibrations may occur in other surfaces and how the mechanical energy is transferred.
That’s why we are asking you as a volunteer for help, so we can track the motion of vibrations as it travels through the steelpan when they develop and decay. So please, continue making classifications as it will continue to help our understanding of the vibrations!