Nyquist Theory Explained Simply

Digital audio is based on capturing sound waves as a series of samples. To do this correctly, we rely on a principle called the Nyquist Theory, which defines the minimum sample rate required for accurate sound reproduction.

What Is the Nyquist Theory?

The Nyquist Theory states that to record a sound wave accurately, the sampling rate must be at least twice the highest frequency you want to capture.

The upper limit of human hearing is about 20 kHz. Twice that is 40 kHz. This is why CD-quality audio uses a 44.1 kHz sampling rate. It safely covers the entire audible range with a margin above 20 kHz.

Why It Matters

If the sampling rate is too low, high frequencies are recorded incorrectly as lower ones. This error is called aliasing, and it produces distortion and an unnatural sound.

By using a sample rate at or above the Nyquist limit, the waveform can be reconstructed cleanly during playback.

What About Higher Sample Rates?

Formats like 96 kHz or 192 kHz go well beyond the range needed to reproduce human hearing. These higher rates may be useful in professional recording and processing, but they are not required to capture the full audible spectrum since everything up to 20 kHz is already covered by 44.1 or 48 kHz audio.

The Nyquist Theory explains why standard digital audio already captures the entire range of human hearing. A sample rate just above twice the top of the audible range is enough to ensure accurate, distortion-free playback.