I’ve always wondered how audio can be recorded to electricity then played back as perfect audio.
In: Technology
Digital audio is made up of a sequence of samples. Each sample is a loudness and if they are played back fast enough, you can recreate the recreate the original sound waves. In math, there is a theorem which describes how many samples you need to create waves: Nyquist–Shannon sampling theorem. In order to fully recreate the waves, you need to sample twice as fast as the highest frequency in the signal. Human hearing can detect sound waves from frequencies from about 20 Hz to 20 kHz, so if the digital audio samples at 40 kHz with enough precision in the loudness levels it can fully recreate the sound.
Now, this doesn’t mean that the digital audio is going to sound the same as playback from a non-digital audio device. Digital audio is almost exclusively done using electronics, while non-digital audio was done mechanically, and the mechanical reproduction usually acts as a low-pass filter, removing some of the high frequency noise. This is why the sound for a record player doesn’t sound the same as from an electronic speaker.
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