What quantity did you change?
Labs / Physics
Sound Beats
Two pure tones that are close in pitch don't just blur together — their waves drift in and out of step, so the combined sound swells and fades. Slide the two frequencies and watch the throb of the waveform, and the loudness meter, speed up as the tones separate and freeze when they lock into unison.
Sound Beats
Two pure tones that are close in pitch don't just blur together — their waves drift in and out of step, so the combined sound swells and fades. Slide the two frequencies and watch the throb of the waveform, and the loudness meter, speed up as the tones separate and freeze when they lock into unison.
Why it matters
Why explore this?
Physics explains how changes in forces, energy, motion, and matter produce results we can measure. This model lets you test one part of that relationship at a time.
Explore
Try the model
fA 220.0 HzfB 223.0 Hzbeat 3.0 Hzloud 100%
Investigate
Questions to test
Predict first, try it in the model, then use what you observe to answer.
What to try
- Slide Tone B toward Tone A. What happens to the throb as the two pitches meet?
- The beat readout says 3 Hz — how many loudness pulses do you count each second?
- What frequency difference makes the beat too fast to hear as a throb, and starts to sound rough instead?
- Turn Amp A and Amp B to equal values. Does the sound ever fade to complete silence between beats?
- If the beat rate is always the difference of the two frequencies, does it matter whether you move Tone A up or Tone B down by the same amount?
Explain
Make sense of what happened
Name the quantity you changed, the quantity that responded, and the physical rule connecting them. Use a readout or visible change as evidence.
Check
Before you leave
What measurable result changed?
Which physical idea connects them?
If you can answer all three using evidence from the model, you understand the main idea. If not, return to Explore and change one setting at a time.