Nyquist Frequency

Here I am at the beach. Instead of frolicking in the water and skipping rocks, I’m thinking about the Nyquist frequency. When we sample something, we’re recording the air pressure as it fluctuates quickly.

You can think of it like these waves lapping at the shore. If the waves occur every two seconds or so, we can’t just take a picture of them every two seconds. If we do, what we get is this.

The idea behind the Nyquist concept, we need to take twice as many samples in order to be able to see or hear what actually happened. Humans can, in theory, hear up to about 20,000 cycles per second. That’s probably generous.

But the implication is that we need to take 40,000 samples in order to document the highest sounds that we can hear. That’s where we come up with the sample rate of 44.1 and 48k. What’s the extra 4,100 samples for?

Well, that’s to build in some smooth filtering so we don’t get jagged edges that create turbulence in those upper frequencies where the cutoff happens. 48k is effectively no different. Musically, it’s almost the same note.

For film and TV, the standard is 24 frames per second. And so we prefer a sample rate that divides evenly into that format. Even the difference between high sample rates and 44k aren’t probably as great as you might think.

If you do the math, you’ll come to the conclusion that the difference between 44.1 and 88.2, it’s literally just an octave higher. If someone who belongs in a beach… If someone in a beach…