Free tool
Online Tone Generator
Play any frequency from 20 Hz to 20 kHz. Drag to change pitch and stereo position, switch waveforms, and watch the harmonics appear. Made for our classes, free for everyone.
Starts muted. Turn your device volume down first, then raise the level slowly. High tones and square waves get loud fast.
Protect your ears: start quiet, especially on headphones. On iPhone, if you hear nothing, check that the volume is up.
How to use it
Press start, unmute, and drag anywhere on the pad. Tap the big number to type an exact frequency.
Pitch
Drag up for higher, down for lower. The scale is logarithmic, so every octave takes the same space, just like your ears hear it.
Pan
Drag left and right to move the tone across the stereo field. Headphones make this obvious.
Level
Use the fader to set loudness. The dot grows with the level and the meter shows the output.
Waveform
Switch between sine, square, saw, and triangle. Anything but sine shows its harmonics stacked above the main note.
The frequency bands
The shaded rows on the pad are the bands engineers talk about when they mix. Park the tone in each one to learn what it sounds like.
Pitch, octaves, and A440
Frequency is how many times a sound wave repeats each second, measured in hertz (Hz). Higher frequency, higher pitch.
Doubling a frequency raises it one octave. A4 is 440 Hz, so 880 Hz is A5 and 220 Hz is A3. That is why the pad uses a log scale: each octave gets the same height.
Under the frequency, the readout shows the nearest note and how far off it is in cents. There are 100 cents in a semitone. Turn on Notes snapping to lock to exact pitches.
Waveforms and harmonics
Every waveform except a sine is a stack of sines: the main note (the fundamental) plus harmonics at 2×, 3×, 4× its frequency and up. Which ones are there, and how loud, is what gives a sound its character. Hover a dot on the pad to read each one.
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Sine: A pure tone with no harmonics. The building block of every other sound.
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Square: Odd harmonics only (3rd, 5th, 7th...), each one quieter by 1/n. Hollow and buzzy.
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Triangle: Odd harmonics too, but they fall off much faster (1/n²). Soft, close to a sine.
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Saw: Every harmonic, falling off by 1/n. Bright and rich, the classic synth lead and bass sound.
Keyboard shortcuts
Active once the generator is started and on screen.
| Space | Mute and unmute |
| ↑ ↓ | Nudge pitch (hold Shift for fine steps) |
| ← → | Nudge pan |
| Z / X | Level down / up |
| E / R | Down / up an octave |
| A S D F | Sine, square, saw, triangle |
| W | Cycle waveforms |
| G | Snap to notes |
| H | Snap to harmonics of the current tone |
| N | Open the note picker |
| T | Sweep 20 Hz to 20 kHz |
| Shift (hold) | Lock pitch while dragging |
| Option / Alt (hold) | Lock pan while dragging |
| C | Center pan |
| V | Back to A440 |
| Q | Reset everything |
Learn what to do with every frequency.
Our mixing and production courses teach you to hear these bands and shape them, in person at our Emeryville campus.