So often we listen to music without thinking how the sound is actually made.  The sounds, the notes, and the melodies seem to simply radiate from the instrument.  Scientists have also overlooked the production of sound in many unique instruments like the steel drum.  Recently the director of the University of Texas at El Paso’s Materials Research Institute, Lawrence E. Murr, encountered his first set of steel drums while visiting the Caribbean.  He was so intrigued by the noises produced from an upside down steel oil drum that he decided the Research Institute must complete a study on the composition and structure.  Murr realized the steel drums’ ability to resonate multiple notes from each strike of the drum had never been thoroughly researched or understood.  These drums had remained largely unstudied and puzzling because of their surprisingly simplistic design. Murr and his team of engineers, chemists, and physicists set out to provide greater insight into the two main components of steel drums, the complicated metal composition and the physical structure of the hammered surface.  The steel drum’s distinctive composition is what turns otherwise random noise into harmonious music.

            Engineers have not determined how the chemical composition of steel (a mixture of carbon and iron) affects sound, but they do know that the atomic composition and structure play an important role in producing the distinct variances in sound.  During manufacturing, the steel drums are first hammered out to create the individual notes.  This hammering knocks the carbon atom’s bonds out of alignment causing further variances in the notes.  Later in the construction of the steel drum, through a process called “strain aging”, heat displaces the carbon atoms at different rates causing more changes in the notes.  The implication of this process, engineers speculate, is the production of up to 30 percent more variance in a note’s frequency.  Engineers are reluctant however, to attribute the huge range of notes solely on the displacement and arrangement of the carbon and iron atoms.

            The other important aspect of steel drum production is the microscopic structure of the hammered surface.  Each note is separated from its neighboring note by grooves or a line of holes.  Even though these painstaking measures are taken to isolate each note, striking one note causes some resonance in neighboring notes.  This factor gives the steel drum part of it’s unique and intricate sound. To see what extent neighboring notes were influenced by the resonance of a single note, Thomas D. Rossing, a physicist at Northern Illinois University in DeKalb, used a process where one note would be struck at a fundamental frequency and then determine which areas on the rest of the playing surface reverberated.  This technique is called holographic interferometry.  He found that, “At amplitudes typical of a performance, almost the entire drum vibrates and radiates sound.”  Thus, when one note is struck during a performance, every other note on the drum reverberates causing a new combination of sounds which is extremely unusual in musical instruments.

            In conclusion, this extensive research has provided great insight into the influence of the two main components of steel drums.  Both the complicated metal composition and the physical structure of the hammered surface have a significant role is the steel drums’ production of music.  Although scientists cannot currently determine the exact amount of influence they have on the music, Murr and his team have undoubtedly proven the metal composition and physical structure play a vital role in the production of the melodious and harmonic sounds of the steel drum.  Without it, the sounds from the steel drum would surely not be pleasing to the ear.  In time this instrument will be thoroughly analyzed and understood but currently the steel drum still puzzles some acoustics experts because of its extremely unique atomic composition and structural design.  As Kaethe George, the manager of the University Tuning Project, said, “As any lover of Caribbean music can tell, though, steelpan makers haven’t done so badly on their own.”

 

Bibliography

Corinna, Wu. "Science catches up with the shimmering sound of steel drums." Science News 154, no. 15 (1998): 27.

Murr, L.E., Ferreyra, E., Maldonado, J.G., Trillo, E.A., Pappu S., Kennedy C., De Alba, J., Posada, M., Russell, D.P., White, J.L. "Materials Science and Metallurgy." Journal of Material Science 34 (1998).