Tone Generator
Generate sine, square, sawtooth, and triangle waveforms at any frequency
The Tone Generator produces precise audio tones from 20 Hz to 20,000 Hz directly in your browser, with four waveforms, note presets from C2 to C6, and a live display of the nearest musical note. Musicians use it as a tuning reference, audio engineers sweep frequencies to find rattles and resonances, and teachers demonstrate pitch and octaves with an exact frequency rather than an approximation.
How to Use
- Set a frequency. Type a value in hertz or pick a note preset. The display shows the closest note name, so 442 Hz is labeled near A4.
- Choose a waveform — sine, square, sawtooth, or triangle. Sine is the default for tuning because it carries no harmonics to confuse the reference.
- Set a comfortable volume and press play. Adjust the slider rather than the system volume for finer control.
- Stop the tone before switching tasks; it keeps playing while the tab is in the background.
Choosing a Waveform
The waveform determines which harmonics ride on top of the fundamental frequency, and that is what gives each its character:
- Sine — one frequency, no harmonics. The purest reference for tuning and the least fatiguing to listen to.
- Square — odd harmonics only, hollow and buzzy. Useful for testing how a speaker handles strong high-frequency content, and as a retro-style sound source.
- Sawtooth — odd and even harmonics, bright and cutting. The richest of the four; good for stress-testing a full-range driver.
- Triangle — a gentler harmonic set, softer than a square. Occasionally used for subtle sound design and for tests where a square is too harsh.
For a hearing check or a speaker sweep, cycle through them: a driver that distorts on a square but not a sine is revealing its behavior, not the tone’s.
Worked Examples
Example 1 — tuning a guitar. Set 440 Hz with a sine wave and play it near the sound hole while tuning the A string. As the string approaches the reference, you hear a slow beating pulse that speeds up and then vanishes at unison. Stop when the pulse disappears — that is a finer cue than trying to judge pitch by ear.
Example 2 — finding a speaker rattle. A bookshelf speaker buzzes somewhere on certain notes. Play a sine tone and slowly sweep from 100 Hz upward until the buzz appears, then narrow the range a hertz at a time. The frequency where the rattle peaks tells you it is a mechanical resonance in the cabinet, a loose grille, or a damaged driver — each a different fix.
Example 3 — exploring your hearing range. Start at 8 kHz and raise the frequency slowly. Most adults hear up to 15–17 kHz, with the ceiling dropping with age; younger ears can reach 18–20 kHz. Doing this at a modest volume with a sine wave gives a rough personal map, though it is not a substitute for a clinical audiogram.
Frequency, Pitch, and Octaves
Frequency is measured in hertz — cycles per second — and higher frequency means higher pitch. Human hearing spans roughly 20 Hz to 20 kHz, though the top end fades with age and the bottom end needs a speaker capable of moving enough air to reproduce it.
Pitch is logarithmic, not linear. Doubling the frequency raises the note by exactly one octave, which is why A4 at 440 Hz and A5 at 880 Hz are the same note in different registers, and why 440 Hz to 441 Hz is a barely perceptible nudge while 440 to 880 is a leap. Western music divides each octave into twelve equal semitones, so moving up one semitone multiplies the frequency by about 1.0595 — a fact worth knowing when you need a tone between two presets.
Protecting Your Hearing and Your Speakers
This tool can produce sustained, full-scale tones — treat it like any other signal generator and respect the output. Keep the starting volume low, especially above 2 kHz where the ear is most sensitive. Avoid long stretches below 50 Hz at high level, because small drivers cannot dissipate that energy. If you hear distortion or the speaker rattles, stop and reduce the level; both are warnings. And keep tones away from sleeping pets and infants, who cannot tell you it is too loud.
Common Mistakes
- Using a square wave to tune. The added harmonics make the pitch harder to match; sine is the right choice.
- Judging level by eye. A half-volume slider position can be loud in one frequency range and quiet in another. Set it by ear, starting low.
- Leaving the tone running. It continues in the background; a forgotten 15 kHz tone playing unnoticed is a poor surprise for the next person in the room.
- Treating a hearing sweep as a diagnosis. It is an informal check, not a clinical test, and relies on uncalibrated hardware.
- Expecting laptop speakers to reproduce 30 Hz. They cannot. If a low tone seems inaudible, the speaker, not the generator, is the limitation.
Features
- Continuous tones from 20 Hz to 20,000 Hz with a numeric entry field
- Four waveforms: sine, square, sawtooth, triangle
- Note presets from C2 to C6, including A4 = 440 Hz
- Live display of the nearest musical note for any frequency
- Adjustable output volume with a safety-first default
- Runs entirely in the browser — nothing is uploaded
Use Cases
- Instrument tuning: A stable reference pitch for guitars, violins, and other strings.
- Speaker testing: Sweep for rattles, resonances, and distortion.
- Hearing checks: Explore the top of your audible range.
- Teaching: Demonstrate frequency, octaves, and harmonics precisely.
- Sound design: A clean tone source for layering and effects experiments.
Related Tools
Frequently Asked Questions
What does the waveform choice actually change?
The waveform changes the harmonic content, which is what you hear as timbre. A sine wave contains only the fundamental frequency and sounds pure and smooth. A square wave adds odd harmonics and sounds hollow and buzzy. A sawtooth includes both odd and even harmonics, giving a brighter edge. A triangle is close to a sine but slightly richer. For tuning, sine is the clearest; for testing a speaker across the spectrum, the richer waveforms expose more.
At what volume should I start?
Start below 50% and raise it only if you need to. High frequencies are more efficient at driving small drivers than low ones, so a level that seems quiet at 100 Hz can be painfully loud at 5 kHz. If a tone causes rattling, distortion, or discomfort, lower the volume immediately — that is the speaker or your ear telling you the level is wrong.
Can I damage my speakers with a tone generator?
Yes, if you play low frequencies at high volume for long periods. Small speakers cannot reproduce very low frequencies efficiently, and the amplifier can push more energy into them than the driver can dissipate, causing overheating or mechanical damage. Keep sustained tones below 50 Hz at low volume, and never use maximum output.
How do I use it to tune an instrument?
Pick the reference preset for the note you want — A4 is 440 Hz, the standard concert pitch — set the waveform to sine for the purest reference, and play the tone while adjusting the instrument until the beats between the two pitches disappear. When the instrument and the tone agree, the audible pulse stops, which is a more precise cue than trying to match pitch by ear alone.
Why does 440 Hz sound different on different devices?
Loudspeakers and headphones are not flat: small drivers emphasize some frequency ranges and roll off others, so the same 440 Hz tone can sound thin on a phone and full on studio monitors. The generated tone is precise; the reproduction is what varies. For calibration work, use known-good headphones rather than laptop speakers.
Does the tone keep playing when I switch tabs?
Yes. The tone is generated through the Web Audio API and continues while the page is in the background, as long as the tab is not closed. Stop it before walking away, both to protect your speakers and to avoid an unexpected tone playing in an empty room.
Reviewed by the HandyTools Hub team · Last updated