How to use it
- Single tone holds one frequency. Type it, drag the slider (logarithmic, so each octave gets the same width), or step by a hertz, a semitone or an octave. “Jump to a note” sets the frequency of any note, such as A4 or C♯3.
- Sweep glides from the start frequency to the end over the time you set. Logarithmic sweeps spend equal time in every octave, which is how we hear pitch and how speaker and room tests are usually run; linear spends most of its time at the top.
- Two tones plays both at once and tells you the beat rate — the difference between them. Set them a few hertz apart to hear the wobble a tuner listens for.
Frequencies to try
- 440 Hz — the standard tuning pitch
- 432 Hz — an alternative tuning pitch
- 1,000 Hz — the standard audio test tone
- 60 Hz — mains hum in North America
- 82.41 Hz — the low E string of a guitar
- 528 Hz — a “solfeggio” frequency
Every note’s exact frequency is in the note frequency chart, the Hz-to-note converter names any frequency, and 432 vs 440 puts the two tuning standards in a blind test.
Frequently asked questions
What is the difference between a sine, square, sawtooth and triangle wave?
A sine is a single pure frequency with no harmonics. A triangle adds only odd harmonics, falling away quickly, so it sounds close to a sine but a little brighter. A square has the odd harmonics at much higher levels, which gives it a hollow, reedy sound, like a clarinet’s low register. A sawtooth has every harmonic, odd and even, and sounds bright and buzzy, like a bowed string or a brass instrument — it is the usual starting point for synth sounds.
Why can I not hear very low or very high tones?
Hearing is usually quoted as 20 Hz to 20 kHz, and the top falls with age. Below 100 Hz or so, phone and laptop speakers produce little or nothing, so a low tone may be silent on the device even though it is being generated. Headphones or a proper speaker reach much lower.
What are beats in the two-tone mode?
Two tones a few hertz apart drift in and out of step, so their combined loudness rises and falls — that pulse is the beat, and its rate is exactly the difference between the two frequencies. 440 against 444 beats four times a second. As two strings are brought into tune, the beating slows and stops, which is how instruments were tuned by ear long before electronic tuners.
Is the tone exactly the frequency shown?
It is generated digitally to well under a hundredth of a hertz. What reaches your ear also depends on the speaker, which can add distortion at high volume — another reason to keep the level moderate.
Can I share a tone?
Yes. The frequency, waveform and mode are written into the page address as you change them, so copying the link copies the setup. For example, adding ?f=1000 opens it on a 1 kHz tone.