How to use Online Tone Generator
A tone generator plays a pure audio signal at an exact frequency you choose, anywhere from a deep 20 Hz rumble to a 20 kHz whistle at the top of human hearing. This one offers four classic waveforms — sine, square, sawtooth, and triangle — plus a volume control, and synthesises the sound live in your browser with no files to download. It is a handy bench tool for testing speakers and headphones, checking your hearing range, tuning instruments, and exploring how different waveforms sound.
- Set the frequency with the slider or type an exact value in Hz.
- Choose a waveform.
- Lower the volume control before you start.
- Press Play Tone.
- Adjust frequency and volume live, then press Stop.
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Frequency, pitch, and waveform
Frequency, measured in hertz, is the number of cycles a sound wave completes each second, and it determines pitch: higher frequency means a higher note. A pure sine wave contains only its fundamental frequency, which is why it sounds smooth and is ideal for hearing tests and calibration. Other waveforms add overtones — a square wave contains only odd harmonics, a sawtooth contains all harmonics — which is why they sound richer and form the building blocks of classic synthesiser sounds. Switching waveforms at the same frequency is a clear way to hear how harmonic content changes timbre without changing pitch.
Testing audio gear and hearing
Sweeping through frequencies reveals a lot about audio equipment. If a speaker buzzes or goes silent at certain points, you have found a resonance or a limit of its range. Comparing how loud the same level sounds at different frequencies demonstrates that hearing is not flat — we are most sensitive in the mid-range and far less so at the extremes. For a rough hearing check, raise the frequency slowly and note where the tone fades; many adults stop hearing well before 17 to 18 kHz. Always keep levels moderate, since the goal is to test gear and ears, not to strain them.
Worked examples
Concert A
Inputs: 440 Hz · sine
Result: Standard tuning reference pitch
Hearing test
Inputs: Sweep to 18 kHz
Result: Tone fades near your hearing limit
Glossary
- Frequency
- Cycles per second of a sound wave, measured in hertz.
- Sine wave
- A pure tone containing a single frequency.
- Harmonic
- A frequency above the fundamental that enriches a waveform.
- Hertz (Hz)
- The unit of frequency: one cycle per second.
Related reading
Frequently Asked Questions
Why use Online Tone Generator?
- Plays any exact frequency across the full 20 Hz to 20 kHz audible range
- Four waveforms — sine, square, sawtooth, and triangle — for testing and synthesis
- Live frequency and volume control with instant response
- Generated locally in the browser with nothing to install or download
Common use cases
- Test the frequency response of speakers or headphones
- Check the upper and lower limits of your own hearing
- Tune an instrument against a reference pitch
- Produce a steady reference tone for audio equipment calibration
- Demonstrate how sine, square, and sawtooth waves differ in timbre
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