Audio has been stored on many mediums over the years. From analog methods like Vinyl, 8-Track, Cassette to digital ones like CD, MP3 and FLAC. Vinyl is a bit of an exception in the general newer-is-better progression that tends to come with technological advancements. The way that audio is recorded onto a Vinyl record is by etching an extremely small groove into the surface of the disc that is a physical representation of the sound waveform. The groove is recorded cylindrically, typically from the outside of the disc inward. You then play the recorded sound back on a turntable where you place a needle inside the groove and when the disc is rotated at the right speed the needle running along the groove picks up all the microscopic impressions and are turned into sound.
Turntable Needle "In the Groove"
The advantage of Vinyl is it is a literal representation of the sound, meaning that when you play it back you are getting as close as possible to the original sound as possible. It can be described as “warmer” and more natural sounding than its digital counterpart the CD. It of course has its downsides like the fact that you are scraping a metal needle against the play surface you physically degrade the record every time you listen to it. Regardless of downsides it is the only analog medium that has stuck around purely because of the way it sounds.
Digital media changed things up in that it samples the audio being recorded at a certain bitrate and frequency (16-bit and 44.1Khz is the standard for a CD). This means that it isn’t a constant stream of information being recorded like in analog, it is just checking for changes very very quickly and storing the sample which is then stitched together to form a digital audio file. Now that the information is digital it can be transferred, copied and modified.
The biggest change from going from analog to digital can be seen when you look at the waveform:
Analog vs Digital Waveform
See how the digital signal looks like a staircase? That's the sampling I was referring to. Now this makes it look like a huge difference, but the sampling is being done as I said "very very quickly" so your brain shouldn't know the difference. Now that is only the first step towards creating something like an MP3, as a CD is stored in an uncompressed state. This isn't a problem when you are playing back the disc itself but what about when you want to take all the songs off that CD and save them to your computer or play it on your phone? For that we need compression... which I will explain in Part 2.