Large groups of cymbals also have the same effect. A drum set could be put in this category. This allows for a larger variety of sound. Glockenspiel Variable Pitch Some of the most interesting instruments to hear are the variable pitch instruments. The biggest physics concept of these is tension.
Tension decides the frequency an object vibrates.
The bigger the tension, the faster vibrations and the higher the pitch. A common example of this are the kettle drums, or the timpani. The timpani are large drums hit with mallets to produce a tuned pitch. There are pedals on the bottom of the drums controlling the sound. The pedals can decrease or increase the tension in the head of the drum, the part the drummer strikes.