What is an acoustic beat?
Alain Bonardi - Christophe Chazot
The study of acoustic beats allows students to easily understand the phenomena of interference on sound waves. The resulting volume oscillation effect produces an effect similar to those used by modern artists in electronic music.
Téléchargez l'activité dans l'application FizziQ.
Onglet "Activités", puis "+", et sélectionner "Scanne un QR Code"
Détails de l'activité
1. Do you know Flume, the electronic music composer. Did you know that it uses a particular effect, the LFO, which you can easily reproduce with your cell phone?
2. Use the Synthesizer in the Tools menu to produce two simultaneous sounds, one at a frequency of 440 Hz, and the other at a frequency of 441 Hz
3. What do you see?
4. The variations in sound intensity seem regular, what is their period? This phenomenon is called a beat
5. Which FizziQ measuring instrument can you use to check the beat period? Record the data produced by this instrument in your notebook and check the beat frequency
6.Use a 2 Hz difference between frequencies, what is the beat period?
7. Try different deviations and deduce the relationship between the beat frequency and the difference in signal frequencies.
8. If the difference is greater than 20 Hz, can you still hear the beat? Why ?
9. By tracing the two waves on a piece of paper, try to understand the origin of this phenomenon.
10. Can you explain how this effect is used to tune instruments in an orchestra?
11. In electronic music the LFO (low frequency oscillations) effect is used by many composers like Flume