ハウリングの仕組み／The Mechanism of Audio Feedbac

DENJIRO: Have you ever experienced something like this? I have here a microphone and speaker. When I put the mic up to the speaker... GIRL: That’s an unpleasant sound! DENJIRO: As you all know, this is audio feedback. But why are these sounds produced? The reason lies in the mic, amp, and speaker. First, sound picked up by the mic is sent to a device called an amp. An amp uses electricity to change the volume of sound. The sound sent from the mic is amplified by the amp. The sound then comes out of the speaker as a loud noise. However, if you bring the mic up to the speaker, the amplified sound is picked up by the mic, the amp amplifies that sound, and the speaker plays it. Then, the mic picks up that sound again. You basically have sound going around in a circle in the setup. As a result, if the mic picks up even a slight sound, the amp amplifies it over and over again, creating this screeching sound. When you get feedback, take the mic away from the speaker. Then you can prevent feedback. Actually, there’s something interesting we can do with feedback. I have here five tubes with different height. What happens if you produce feedback inside the tubes? You can produce sounds of a certain pitch. Now, let me perform a song. GIRL: How interesting! DENJIRO: The pitch is determined by the length of the tube. By bringing the mic up to a tube, I can produce feedback that has a certain pitch. I hope energy will bring you all happiness. Our magic word is "Happy Energy!"