電子楽器の仕組み／The Mechanism of Electronic Instruments

DENJIRO: Can you guess what this is? GIRL: What is that? DENJIRO: Let me show you. GIRL: What a strange sound! DENJIRO: This is an instrument called a “theremin.” It’s the world’s first electronic musical instrument. With a normal instrument, you touch it with your hands to produce sound. But with a theremin, you can electronically control sound through an antenna without touching it. You create vibrations with electricity by adjusting the distance between your hand and antenna, and that is how the sound is created. A famous electronic instrument that we all know is the electric guitar. So how does it produce sound? I’ve prepared a model here to recreate the mechanism of an electric guitar. The model has a steel string and a copper string. A guitar produces sound by vibrating strings like these. Let me pluck the strings as is. It’s very quiet. In order to produce a loud sound, you need a coil that has a metal rod and a magnet attached to it. This is called a “pickup.” I’m going to connect the pickup to an amp, bring it up to the steel string, and pluck it. GIRL: The sound is louder! DENJIRO: That’s right, the sound got louder. The magnet on the metal rod magnetizes the steel string. And when this magnetized string vibrates, electricity runs through the coil. This means that the pickup is converting the steel string’s vibration into an electrical signal. Now, let’s try it with the copper string. We only get a quiet sound. Since a copper wire cannot become magnetized, the vibration cannot be converted into an electrical signal. NARRATOR: This is where the pickup of an electric guitar is attached. DENJIRO: I hope energy will bring you all happiness. Our magic word is "Happy Energy!”