The Turnplayer and the Gramophone Records
They're back all the way, the record players! (For a while:)
It used to be that you could only hear a sound at the moment itself. If the sound waves were gone, you could never hear the sound again. Fortunately, then came the invention of the record player and the tape recorder. Suddenly people could hear everything, and as often as you wanted.
The music that was played converted the microphone (in the recording studios) into electrical signals. Those signals were amplified and recorded on a tape. Some more work was done and then the vibrations were put on a plastic plate. The wave-shaped grooves were made in them by a vibrating needle. Metal dies were made of that plastic sheet (molds). So they could make the plastic plates, which you could buy from all kinds of music in the store.
