PURPOSE: To demonstrate the effect of the critical band on the sound of two simultaneous sine waves.
DESCRIPTION: Set the two oscillators to equal amplitudes and the amplifier in monaural, with one at 500 Hz. Starting at less than 100 Hz, sweep the frequency of the second oscillator slowly past that of the first oscillator. When the two oscillators come within about 20 percent in frequency, a coarseness can be heard. This coarseness arises from the overlap of the critical bands of the two tones. Moving the two frequencies closer creates beats.
REFERENCES: (PIRA 3C55.35)
EQUIPMENT: Two oscillators with amplifier and loudspeakers on Audio Cart.
SETUP TIME: 5 min.
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