Educational data logger

Introduction

The ear can not distinguishing between two sound waves with a small frequency difference and equal amplitude, the result is that a high frequency and a lower frequency sound is heard. This low frequency sound is known as beating.
The microphone on DrDAQ will enable us to see the beat effect of sound waves.

Equipment required

Experiment set up

  • Connect each signal generator to one of the loudspeakers and point them into the room placing DrDAQ in the centre, as shown in figure 1.
  • Both signal generators should be set to a frequency of approximately 500 Hz.
  • PicoScope should now be setup to detect sound (not level) from the speakers, using a timebase of 10 ms/div.
  • Switch each of the signal generators on independently, making sure that the amplitude of each soundwave at the microphone is almost identical.
  • The equipment is now set up for the experiment.
Equipment set up

Figure 1: picture showing the set up of the equipment.

Carrying out the experiment

  • Switch on both signal generators.
  • Adjust the frequency on one of the signal generators until beating can be heard.
  • Capture the waveform seen on PicoScope of the waveform.
  • Using the frequency meter in PicoScope make a note of each of the individual frequencies f1 and f2 for the two signal generators by turning each generator off in turn.

Questions

  1. Estimate the beat frequency of the sound wave.
  2. Estimate the two frequencies of the sound waves from the signal generators.
  3. What would happen if the amplitudes of the two sound sources were not equal?

Results >