You plug in new speakers, or a secondhand pair of headphones, and want to check both channels work and no particular frequency is missing. Playing a song doesn't help with that — you need a pure tone, a single exact controlled frequency, with nothing else mixed in.
What a pure tone is, and why songs don't work for this
A song is a mix of hundreds of simultaneous frequencies — voices, instruments, harmonics — constantly changing. It's impossible to isolate whether a speaker mishandles a specific frequency while listening to normal music. A pure tone, on the other hand, is a single constant frequency, mathematically generated by an oscillator. If something's wrong at that exact frequency (a damaged speaker, a hearing loss in that range), it's immediately noticeable because there's nothing else playing to mask it.
The four waveforms
- Sine: the purest possible wave, a single tone with no added harmonics. It's the standard reference for frequency testing.
- Square: alternates sharply between two levels. It sounds harsher because, mathematically, it contains a series of odd harmonics on top of the fundamental frequency.
- Sawtooth: rises linearly and drops abruptly, repeatedly. It contains every harmonic (odd and even), giving it a brighter, more metallic timbre typical of analog synthesizers.
- Triangle: similar to sawtooth but with a symmetric, smoother rise and fall. It sounds duller than square, with fewer high harmonics.
Practical uses for a tone generator
- Testing speakers or headphones channel by channel: a tone in a single ear or speaker immediately reveals a dead or distorted channel.
- Finding the range of your own hearing: healthy human hearing perceives between 20 Hz (low, almost a vibration) and 20,000 Hz (high, a thin whistle) — and that range narrows with age, especially at the high end. Sweeping the generator from 20 to 20,000 Hz gives a quick sense of where it stops being audible.
- Reference tone (A440): 440 Hz is the standard A note used to tune musical instruments.
- Tinnitus frequency matching: some people use a tone generator to try to identify the approximate frequency of a ringing they perceive, though this doesn't replace a medical evaluation.
Frequently asked questions
Can I download the tone as a file? Yes, a WAV file is generated from the chosen frequency, waveform, duration and volume.
Why does the tone have a very short fade at the start and end? To avoid the click a sudden cut of the wave would cause — the same reason an audio fade smooths out cuts in general.
What frequency range is available? From 20 Hz to 20,000 Hz, covering the full theoretical range of human hearing.
Is everything generated locally? Yes, using the browser's own Web Audio API oscillator, with no connection to any server.
Generate pure tones at any frequency and waveform with the tone generator, listen live or download them as WAV.