Here's how it works:
* Air is pumped into the harmonium: You use the bellows to force air into the instrument.
* Air flows through the reeds: The air then passes through small metal reeds, which are similar to those in a mouth organ.
* Reeds vibrate: The pressure of the air causes the reeds to vibrate. The frequency of this vibration determines the pitch of the note.
* Sound is amplified: The vibrations of the reed create sound waves which resonate within the harmonium's body, amplifying the sound.
So, the reed is the essential component that vibrates to produce sound in a harmonium.
