Understanding MIDI and Frequency
In digital music, pitch is categorized into 128 discrete numbers called MIDI Note Numbers. While these numbers are convenient for software and DAW sequencing, they don't directly describe the physical vibration of air. To understand how a synth or sample resonates in a mix, we must convert these numbers into Hertz (Hz).
The Conversion Logic
Modern musical tuning centers around A4 = 440 Hz, which is MIDI number 69. The relationship is logarithmic, meaning every octave (12 notes) doubles or halves the frequency. The standard formula is:
Frequency = 440 × 2^((MIDI - 69) / 12)
Production Reference Points
- Typical Sub Bass: MIDI 24 (C1) to MIDI 36 (C2), spanning approximately 32 Hz to 65 Hz.
- Lead Melodies: Usually occupy the MIDI 60 (C4) to 84 (C6) range.
- Human Hearing: Stretches from MIDI 0 (8 Hz, though below hearing) up to the highest notes of MIDI 127 (12.5 kHz).