… Musical instruments, the sound of which is produced, or must be amplified, electrically (for example, organs, guitars, …
Explanatory notes
… instruments, the sound of which is produced, or must be amplified, electrically (for example, organs, guitars, … struck by a hammer, give rise to variations in capacitance between the wire and metal parts (studs) adjacent to it. The … others may be adapted to an ordinary piano, the instrument being played with the right hand while the piano …