Tone Generator

How to use the tone generator

1. Set your frequency.

   Drag the slider, type a number directly, or pick a musical note from the dropdown — all three stay in sync.

2. Choose a waveform.

   Sine, square, sawtooth, and triangle each sound noticeably different — pick whichever suits what you're testing or listening for.

3. Press Play.

   The tone plays continuously until you press Pause — adjust the frequency or waveform freely while it's playing to hear the change live.

4. Use ×½ and ×2 to jump an octave.

   Handy for checking whether you've confused two tones that are actually an octave apart, which happens easily with pure tones.

5. Adjust balance for one-ear listening.

   Drag fully left or right to send the tone to only one ear or speaker — useful for hearing checks and the binaural beats experiment below.

What this tone generator is used for

Musicians and audio technicians use it to test audio equipment — checking a speaker or subwoofer's actual usable frequency range, or diagnosing a wiring or playback problem by ear. A sudden crackle, drop-out, or buzz at a specific frequency and nowhere else is a strong clue about exactly what's failing, in a way that music alone rarely reveals so cleanly. If a speaker turns out to have a genuine problem, our Sound Test is a faster next check for basic left/right channel and playback issues.

It doubles as a basic tuning reference too: pick the note you need, like A4 for a guitar's A string, and tune against it by ear. This is genuinely how tuning worked for most of musical history before electronic tuners existed, and plenty of experienced musicians still prefer it for a quick sanity check.

Plenty of people also use it to test their own hearing, sweeping through frequencies to find the highest and lowest tones they can perceive — healthy young ears typically span about 20 Hz to 20,000 Hz, though the top end fades with age, often starting in the mid-teens and continuing gradually from there. And if you experience pure-tone tinnitus — a persistent ringing or whining sound with no external source — matching its pitch here, a process audiologists call tinnitus frequency matching, is a common first step toward finding a masking sound that helps. It's worth repeating that this tool is not a medical device and can't replace an actual hearing test from an audiologist, but it's a reasonable starting point for curiosity or for preparing questions before a real appointment.

Choosing the right frequency for common tasks

If you're not sure where to start, this table covers the frequencies people reach for most often.

Understanding waveforms

All four waveforms here are "periodic" — they repeat in a steady loop, which is what makes them sound like a constant, unchanging tone rather than noise.

Every one of these can be built by combining sine waves at different frequencies and volumes — a sine wave is the basic building block that all the others are made from, which is also why it sounds the most "pure."

Try it yourself: acoustic and binaural beats

Acoustic beats. Open this page in two browser tabs. Set one to 600 Hz and the other to 602 Hz, then play both at once. Instead of hearing two separate pitches, you'll hear a single pulsing tone rising and falling a couple of times a second — a genuine physical phenomenon caused by the two close frequencies interfering with each other in the air, not an illusion of your ears.

Binaural beats. This one needs headphones. Open two tabs again — set one to 440 Hz with balance dragged fully left, and the other to 444 Hz with balance dragged fully right. Play both. Each ear now hears a slightly different pitch, and your brain itself perceives a third, pulsing tone that doesn't actually exist in the air at all. Some people use this while meditating or trying to fall asleep, though the research on any deeper benefit remains mixed.

Frequency ranges worth knowing

Tuning standards: why A4 is 440 Hz

The note A above middle C is set at 440 Hz by international agreement — a standard called A440, formally adopted in 1955 and still the default reference for orchestras, electronic tuners, and this tone generator today. Every other note's frequency in standard Western tuning is calculated from that single reference point using equal temperament, the system that divides each octave into twelve equal steps.

It wasn't always 440 Hz, and it still isn't everywhere. Orchestras drifted higher over the 19th and 20th centuries chasing a brighter sound, and some ensembles today — particularly in parts of Europe — tune slightly higher, to 442 or 443 Hz. A separate, smaller movement argues for retuning to A432 Hz instead, a figure sometimes associated with claims about resonance and wellbeing that don't hold up to acoustic scrutiny, but which persists online regardless. Both A440 and A432 are simply reference choices, not universal physical constants — the note dropdown on this page uses the A440 standard, which is what the overwhelming majority of instruments, recordings, and tuners are built around.

A short history of the tone generator

Before software made this instant, generating a precise, stable tone took dedicated hardware. Early electronic tone generators emerged alongside the telephone and radio industries in the early 20th century, built from vacuum tube oscillator circuits and used to calibrate equipment and test transmission lines. Physical audio oscillators remained standard test-bench equipment in electronics and audio engineering for decades, and dedicated hardware tone generators are still manufactured today for professional lab and broadcast use.

The Web Audio API — the browser technology this page runs on — brought that same core capability to any device with a browser, no hardware or installed software required. What used to need a dedicated oscillator circuit costing hundreds of dollars is now a few lines of JavaScript, which is exactly why tone generators like this one are free and instant rather than a paid professional tool.

What is tone, and how is it produced?

Every sound you hear starts as a vibration. A guitar string, a speaker cone, your own vocal cords — something physically moves back and forth, pushing the air around it into a wave that travels to your ear. How fast that vibration repeats is its frequency, measured in Hertz (one Hz means one full vibration per second), and frequency is what you perceive as pitch: faster vibrations sound higher, slower ones sound lower.

This tone generator produces a "pure" tone — a single, exact frequency with nothing else mixed in. That's actually unusual in the real world. A guitar note, a human voice, or a car horn is really a fundamental frequency plus a whole stack of quieter harmonics layered on top, and it's that specific mix of harmonics that gives an instrument or a voice its recognizable character. Stripping all of that away to a single frequency is exactly what makes a tone generator useful for testing — there's nothing to complicate the signal, so any problem you hear is coming from your equipment or your ears, not from the source.

Fixing common tone generator problems

No sound at all. Check your system volume and output device first, then confirm the volume slider on this page isn't at zero. Some browsers also block audio from playing until you've interacted with the page at least once — click anywhere on the page, then press Play again.

The tone cuts out or sounds distorted. This is almost always the volume set too high for your speakers or headphones at that particular frequency, especially at the low and high extremes. Lower the volume slider and see if it clears up.

You can't hear anything at a very low or very high frequency. This is often your hearing or your speakers reaching their natural limits rather than a fault — very few consumer speakers reproduce much below 40–50 Hz convincingly, and human hearing for very high frequencies fades with age. Try a mid-range frequency like 1,000 Hz to confirm everything else is working normally first.

More tools on ProDeviceTest

Troubleshooting a whole setup rather than just testing a frequency? These run the same way — instant, no download, right in your browser.

• Sound Test — check left/right channels and a full frequency sweep
• Mic Test — check your microphone with a live waveform
• Voice Recorder — record, trim, and download audio
• Webcam Test — verify your camera before a call
• All Audio Tools — the full category