How does electromagnetic induction work in a large audio speaker?
In an audio speaker we do use a permanent magnet and a light copper coil. Like a motor electric current forces the coil to move, but not in a rotational manner. The audio speaker moves in a very limited forward and backward direction. Werner von Siemens was one of the first to conceptualize a loudspeaker, but the details of how to accurately and powerfully reproduce frequencies... and have it sound like something was a trick that was finally figured out in 1921 in Schenectady, NY by CW Rice and EW Kellogg.
How does it work?
The modern speaker uses an electromagnet to turn electric signals of varying strength into movement. The coil of copper wire moves as the magnet energizes. This works using induction. The coil is connected to a cardboard/paper/vinyl "cone". The cone is a diaphragm that vibrates along with the coil. Sound is created and amplified by the diaphragm. There are variations on how to build the speaker. A given speaker is designed to produce a specific frequency range. Not all materials and construction designs produce all sounds the same