Once upon a time, there was no recorded music.
To hear music you needed to go to a live performance. Eventually sheet music was printed and available to buy. If you liked the song, you bought the sheet music … if you were lucky enough to have an instrument and could play you could actually hear the song.
The piano (or other musical instrument) was an important part of home entertainment.
In the late 1800s, Thomas Edison developed the idea of moving a piece of tin foil under a needle that was attached to something like a stretched out balloon. When he spoke into the piece of balloon, the attached needle vibrated and those vibrations were stored in the sheet of tin that he moved under the needle. He invented the Phonograph and in 1887 formed the first record label, selling records that were cylinders with sound scratched along the outside, played on a hand-cranked device.
Emile Berliner (who had a hand in the invention of the microphone) patented a flat disk system that was better than the tube, called the Gramophone. His system eventually incorporated a spinning flat disk with sound scratched in a spiral played back on systems with needles connected to stretched-balloon type membranes that were themselves connected to large open flaring horns (like a tuba) to help the sound waves radiate out in a single direction with extra resonance from the horn itself. The system was crank-wound, and elaborate springs and gears would then spin the disc at a constant speed.
Eventually, sound was being captured by microphones and stored magnetically on steel wire magnetic recorders, which used spools of wire that would follow a path from a “supply” spool to a “take up” spool, passing a record head that stored the magnetic sounds onto the wire and a play head that could read the magnetic signals back from the wire. This was accomplished using electro-magnetic transducers rather than early technologies that utilized physical transfer of sound energy.
Steel wire recorders were developed using technology that was first proposed in the late 1870s, and were used at times to send secret messages (for example, in a shipment of piano wire).
In the 1950s, oxide-based magnetic tape replace steel wire as the material to store magnetic signals onto. Tape used magnetically sensitive particles glued to a wide piece of plastic, which allowed for more focused and controllable recording and eventually the ability to record multiple bands (tracks) rather than a single sound.
Magnetic tape recorders utilized many of the same features as steel wire recorders, including supply reel, take-up reel, record head, playback head, and tape path.
Magnetic tape can be saturated, which means that if the tape is overloaded it will compress the sound. Magnetic tape has a “hiss” on playback. Different methods used to reduce the noise include dbx and Dolby, which crank up the hiss while recording and then drop it back down when playing back (reducing the tape hiss along with the “cranked” hiss). “Single-ended noise reduction” devices do not change the recorded sound, but rather will gate the high frequencies on playback.
Les Paul (yes, the Les Paul) created a magnetic tape recorder with a sync head (a record head with limited playback abilities).
This was the invention of sound on sound recording.
Previously, if you were listening back to something that was playing back and recorded something new, the new would not be at the same physical point along the tape because the playback head and the record head were in two different physical locations. The sync head meant that you could listen back to sound and record new sounds at exactly the same point along the tape.
Suddenly, we have multi-track recording, allowing people to record up to eight different tracks individually and listen to the tracks on newly developed equipment called mixers that controlled the volume of the tracks both going into and out of the machine, and also mixed those sounds together at those controlled volumes.
Suddenly, you could re-perform one part on one instrument rather than be forced to re-perform the entire song with all the musicians. You could even erase and replace small parts of individual tracks rather than have to re-do everything, as long as the sounds were separated enough when you recorded them that each track contained only the sound of one instrument. Replacing small parts involved going into and out of record at specific times, which was called punching in and punching out.