Monday, January 30, 2012

Ear of the Beholder--Part 2


So the students and I faced an ongoing struggle that is created when an objective scientist is trying to reach a group of subjective musicians. They often were skeptical of the scientific material in our text. Luckily, I was teaching a laboratory course, so I was able to introduce them to the experimental method, wherein they could prove to themselves the truth of the physical properties of their musical instruments.

I ran into stiff resistance when we studied acoustic properties of their instruments that sometimes countered the message they were given by the conservatory staff. For example, brass players had been taught that the specific metal alloy of their instrument had a defining role in its sound quality. Woodwind players had been taught that the quality of sound they made was strongly dependent on whether the clarinet or oboe was made of an exotic tropical wood or a good grade of plastic. In fact, tests have shown that the material of a musical instrument has minimal influence on its tone. It’s much more a function of the shape of the instrument’s inner air column and the qualities of the player’s embouchure (the way that the player applies her lips and tongue to the mouthpiece). Unfortunately, there are no unequivocal tests that we could conduct in a college lab that would unambiguously evaluate sound quality, so our credibility gap in that area remained.

I did manage to come up with one lab test that was able to refute one of their main beliefs. We were studying in our text the subject of what distinguishes the sound of one musical instrument from another. How does one tell the sound of a violin from a trombone, or a clarinet from a trumpet? The answer seems obvious to anyone who has listened to music. They are very distinctive. The author of our text described that the main distinguishing characteristic was not the nature of the tone of an instrument, but unique qualities that can be heard at the very beginning and ending of a note. It’s not the steady tone that is distinctive, it’s the transient sounds on each end of a note.

This result seems to go against the experience of anyone who is at all familiar with music. As expected, the students were very resistant to the message. So, together we designed an experiment to test it out in our next lab. They all brought their instruments—clarinet, trombone, flute, trumpet, guitar, violin, cello, French horn, oboe, saxophone, and even voice. We picked a note that every instrument could play at the same pitch—I think it was A above middle C.

Each student stepped to the microphone and played that note for about 30 seconds, as we recorded it on tape. We chose one student to go alone into another room and erase the first and last couple of seconds from each recording—leaving only the steady, middle part of the note. He then scrambled the order of the recordings—making his secret notes as to the new sequence.

He then came back into the lab and played the 20-second samples, as the students listened and made their choices of which instrument made which tone. It surprised me at how similar the notes sounded, as I watched looks of consternation and perplexity cross their faces. They were clearly taken aback. When all tones had been played, I asked them if they wanted to listen to them again, before making their final choices. All heads nodded approvingly, brows knitted.

At the end of the second round, we tallied the scores. It was quite astonishing: on average, the class had correctly identified only one-third of the instruments. Their response to the test was somewhere between being awestruck and disbelief. I don’t think they became instant converts to the scientific principle, but it sure made an impression on them. They had proved to themselves something about the physics of sound that countered their subjective experience. For the rest of the course, the communication gap between us seemed a bit narrower.


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