Audio Frequency Converter
Bidirectional conversion between physical frequency (Hz), musical note pitches, MIDI numbers, acoustic air wavelength, and studio delay times.
| Musical Note Value | Delay Time (Milliseconds) | Dotted Note ms (+50%) | Triplet Note ms (× 2/3) | Modulation LFO Rate (Hz) |
|---|
How to Convert Frequency (Hz) to Notes and Delay Times
In audio production and musical performance, the same sound event can be described in multiple units: a physicist measures physical cycles per second (Hertz), a keyboard player reads musical note names (A4) or MIDI numbers (69), a studio engineer sets echo delay times in milliseconds, and an acoustician calculates physical sound wave lengths in meters or feet.
| Frequency (Hz) | Musical Pitch Reference | Wavelength in Air | Practical Studio & Room Implication |
|---|---|---|---|
| 30 Hz | Sub-Bass (Low B on a 5-string bass) | 11.4 meters (37.5 ft) | Massive waves; builds heavy bass pressure in room corners |
| 100 Hz | Bass Punch (Kick drum fundamental) | 3.4 meters (11.2 ft) | Creates strong standing waves and boomy room resonance |
| 440 Hz | Concert Pitch A4 | 78 cm (30.7 in) | Easily absorbed by standard 2-inch to 4-inch acoustic foam or fiberglass |
| 1,000 Hz (1 kHz) | Vocal Midrange clarity | 34 cm (13.5 in) | Primary speech intelligibility zone; absorbed by wall drapes and panels |
| 10,000 Hz (10 kHz) | Treble Air & Cymbal shimmer | 3.4 cm (1.3 in) | Tiny ripples; easily scattered by diffusers, furniture, and curtains |
When a bass wave strikes a solid wall, the air motion right at the wall surface slows to a stop. Standard porous acoustic panels absorb sound best where air particles are moving fastest — about a quarter of a wavelength away from the wall. Leaving a 5 to 10 cm (2 to 4 inch) air gap behind your acoustic panels doubles their low-frequency absorption without needing thicker fiberglass.
Setting Delay and Reverb Times to Match Your Song BPM
When adding delay or reverb in your digital audio workstation (DAW), matching echo repeats to the tempo of the song prevents muddiness and keeps the groove tight and punchy:
- Quarter Note (1/4): Divide 60,000 by your song's BPM. At 120 BPM, a quarter note is exactly 500 ms.
- Dotted Eighth Note (1/8d): Multiply the quarter-note delay by 0.75 (375 ms at 120 BPM). This creates the iconic rhythmic galloping echo made famous by U2 and modern ambient guitarists.
- Triplet Eighth Note (1/8t): Multiply by 0.333 to lock with swing beats and blues shuffles.
Frequently Asked Questions
When mixing songs, setting delay and reverb pre-delay times to exact musical subdivisions (like 1/4 or 1/8 notes in milliseconds) synchronizes your echoes to the song tempo so effects groove smoothly with the beat without muddying the mix.
Sound travels at about 343 meters per second in air. Deep bass notes produce massive physical waves (a 40 Hz kick drum wave is over 8 meters long), which is why bass frequencies easily pass through walls and pool in bedroom corners.