To help students understand why every instrument sounds different, you might try using a synthesizer in your music class.
Free or inexpensive software emulations of hardware synthesizers can be easily found online.
The sound of a synthesizer begins with the oscillator — acoustically, this has its equivalent in an instrument’s sound source. In orchestra class, sound is created by friction between a bow and a string. But why does a string bass sound different from a bass clarinet, even when it plays the same note?
The answer is harmonics. Each partial of the overtone series is accounted for in stringed instruments (the same holds true for the human voice, which is essentially a stringed instrument), whereas reed instruments only include every other harmonic. On a synthesizer, this contrast can be shown by switching between a sawtooth and a square wave in the oscillator section.
Another basic piece of synthesis is envelopes, also called ADSRs. ADSR stands for Attack, Decay, Sustain, and Release. Have your students help you adjust each parameter to best match the sounds of familiar instruments.
Vibraphones will have a sharp attack, very little sustain and a long release, while a bowed violin will have slightly longer attack, a long sustain and not much of a release.
Try it for yourself, or even better, have your students take turns experimenting with the synthesizer software.
To find other ideas for your orchestra class, head over to the Orchestra forum.
—Gregory Reinfeld, September 14, 2011, © National Association for Music Education (www.nafme.org)