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Play a steady reference tone at any frequency between 20 Hz and 20 kHz with your choice of waveform. Useful for tuning, calibration, speaker tests, or simply learning what each waveform sounds like. The browser does the synthesis — no plugin or download needed.
Each waveform has a different harmonic structure and timbre.
Common reference pitches and calibration tones.
A tone generator produces a continuous sound at a specific frequency — a pure pitch, like the steady note from a tuning fork. Unlike music, which is usually a complex mix of harmonics and timbres, a generated tone has a clean, predictable shape. That makes tone generators the workhorse of every audio engineer's toolkit: you use them to tune instruments, calibrate microphones, test speaker frequency response, set channel levels in a studio, and verify that an audio chain isn't introducing artifacts. This tool runs entirely in your browser using the Web Audio API and supports the four classic waveforms — sine, square, sawtooth, and triangle — across the audible range from 20 Hz to 20 kHz.
Sine is the cleanest single-frequency signal — best for hearing tests and calibration. Square and sawtooth are bright and harsh because they contain many harmonics. Triangle is mellower than sawtooth but still has odd harmonics.
Use the log-scale slider for broad sweeps, the numeric input for exact values, or click a preset for common pitches like A4 (440 Hz) or 1 kHz.
Audio plays through your default output. Lower the volume slider to a comfortable level — high frequencies and square waves can sound piercing at high gain.
While the tone is playing, you can change the frequency, waveform, or volume — the changes are applied smoothly without restarting the oscillator.
Each waveform is the same fundamental frequency, but with a different set of overtones (Fourier components): Sine — the fundamental only, no harmonics Triangle — odd harmonics that fall off as 1/n^2 (mellow) Square — odd harmonics that fall off as 1/n (hollow) Sawtooth — all harmonics that fall off as 1/n (bright, buzzy) Concrete shapes at fundamental f: sine(t) = sin(2πft) square(t) = sign(sin(2πft)) triangle(t) = (2/π) · arcsin(sin(2πft)) saw(t) = 2(ft - floor(ft + 0.5))
Pitch — the perceived note — is determined by the fundamental frequency, not the waveform. A 440 Hz square wave and a 440 Hz sine wave are both an A4, but they sound different because the square wave includes loud upper harmonics. Sine is the only waveform that produces a single pitch with no overtones, which is why it's used for hearing tests and audio measurements: you know exactly what the speaker is being asked to reproduce. The other three waveforms are useful for testing how an audio chain handles harmonic content — clipping, distortion, and frequency response problems are much easier to spot in a sawtooth or square wave than in a sine.
Reference: MDN — OscillatorNode (Web Audio API)
| Setting | What it sounds like |
|---|---|
440 Hz sine | Tuning fork A above middle C The reference pitch used by orchestras worldwide. |
1 kHz sine at low volume | Standard test tone Used for level calibration in audio engineering. |
60 Hz sawtooth | Buzzy hum, like an electrical fault Mains-frequency reference (50 Hz in EU). |
10 kHz square at high volume | Piercing whistle Demonstrates how harmonics push energy into very high frequencies. |
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