PURPOSE: To demonstrate second order or quality beats.
DESCRIPTION: One oscillator is set at about 200-500 Hz sine wave, and the other set to the second harmonic (an octave higher) but with about half the amplitude of the fundamental. If the octave is slightly mistuned, the phase of the second harmonic will be continuously changing with respect to that of the fundamental. The slight change in tone quality or timbre is known as "quality beats" or "second order beats." Inasmuch as quality beats are significant, this experiment provides a counterexample to the general statement of Ohm's Law of Hearing.
SUGGESTIONS: Set amplifier to monaural.
REFERENCES: (PIRA unavailable.)
EQUIPMENT: Two oscillators with audio amplifier and loudspeakers on Audio Cart.
SETUP TIME: 5 min.
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