About Nyquist Frequency Calculator
Digital audio is a game of compromise. We chop up continuous sound waves into discrete "samples". But how fast do we need to sample to capture the music accurately? The Nyquist Formula Calculator helps you understand the frequency limits of your digital system, based on the fundamental theorem of Digital Signal Processing (DSP).
The Nyquist-Shannon Theorem
This theorem states that to perfectly reconstruct a waveform, you must sample it at least twice as fast as the highest frequency component present in the signal. This "highest frequency" is known as the Nyquist Frequency.
Nyquist Frequency = Sample Rate / 2
Real World Impications
- Why 44.1 kHz? Humans hear up to roughly 20 kHz. To capture 20 kHz, we need a sample rate of at least 40 kHz. The extra 4.1 kHz allows room for an "Anti-Aliasing Filter" to gently cut off frequencies above 20 kHz without distorting the audible band.
- Aliasing - The Enemy: If you try to record a frequency higher than the Nyquist limit (e.g., a 25 kHz ultrasonic sound on a 44.1 kHz system), it doesn't just disappear. It "folds back" into the audible range as a nasty, dissonant metallic noise. This is called Aliasing.
- Why go higher? Recording at 96 kHz (Nyquist = 48 kHz) pushes this filtering process far away from human hearing, resulting in a cleaner, more phase-accurate high end. It also allows for extreme pitch-shifting/slow-motion effects without dulling the sound.