Mondo Knows Facts
You must sample at least twice as fast as the highest note
Below that rate, frequencies fold back and appear as false tones Harry Nyquist and others described the limit in the 1920s, before digital audio existed. Engineers use filters to remove anything above half the sample rate before conversion. The rule governs every digital recording and video capture. It sits in Mondo's music collection, one of 200 facts that each trace back to the reference below.
Where this comes from
Facts that can change over time are reviewed and updated. If something here looks wrong, Mondo would rather know than be confidently incorrect.
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More facts like this
The blues runs on twelve barsThree chords, one per four bar phrase, with the fifth bar turning the cornerThe circle of fifths orders every keyMoving one step adds a sharp or removes a flatSome instruments sound at a different pitch from the notes writtenA written C on a B flat clarinet comes out as B flatSonata form sets two ideas against each otherExposition, development and recapitulation is the usual patternA single note already contains a whole chordThe harmonic series stacks octave, fifth, fourth and third above the fundamentalA minor key lowers the thirdFlattening one note changes the whole emotional colour of a scale
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Tags: digital, theory, physics
You must sample at least twice as fast as the highest note: the short answers
- Where does this come from, and can I check it?
- Below that rate, frequencies fold back and appear as false tones. The figure is taken from Britannica, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.
- Is this really a music fact?
- Yes. It sits on the Music shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.
- What else can I read about it?
- The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.