First, Analog Audio…
As you know, computers can only work with binary data, or “0’s and 1’s”. The zeroes and ones represent two states, either “off” or “on”. This is like having lots of tiny switches that form a sort of super-fast Morse Code, which a computer uses to represent real world events (such as musical sounds) in what is known as binary code.
The audio we hear from our stereos and home entertainment systems is ‘analog audio’. This means that oscillating voltages are used to represent the original sounds. Here’s how this works:
A saxophonist plays a note in a smoky basement jazz club. The vibrating air coming from the horn moves the air in the smoky room, and your eardrums vibrate back and forth along with the vibration of the air molecules. We experience these vibrations as “sound”.
A microphone and an analog tape recorder are set up in the room. The saxophone vibrates the air around it, setting up a series of pressure changes that radiate through the air in the room. When these pressure changes reach the microphone’s diaphragm, it shakes back and forth with the vibrations, much like the tympanic membranes in our ears. The microphone “hears” these vibrations and converts them into electrical voltages that are an “analogy” of the air pressure changes that made the original sounds. The tape recorder’s record head then stores these electrical voltages (“analog audio signal”) on magnetic tape as magnetic fluctuations.
After the set is over, we take the tape recorder home and hook it up to our stereo system. Now we can play the recording back. We play the tape, the magnetic fluctuations on the analog tape are converted to electrical voltage changes (analog audio signal) by the tape playback head and the resulting voltages are sent to our stereo amplifier. The amplifier changes those fluctuating voltages into current fluctuations which move our stereo speakers back and forth, far and fast enough to create disturbances in the air of our listening room that are almost exactly the same as the original vibrations caused by the saxophone playing in the jazz club. That’s High Fidelity analog audio!
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