Online Tone Generator

How to use the online tone generator

This online tone generator is a free frequency generator that plays a test tone at any frequency from 1 Hz to 22,050 Hz: pick a sine, square, sawtooth or triangle wave or noise, set the volume and speaker, or run a frequency sweep. It all runs in your browser. Press Play to start and press it again to stop. The sound fades in and out, so there is no click.

Set the frequency three ways: type it in the Frequency box (decimals work, like 432.5), drag the slider, or use the step buttons: ±1 and ±0.1 Hz, ±semi for one semitone and ±oct for one octave. The slider is logarithmic, so each decade (10, 100, 1,000 Hz) gets the same space. The display shows the nearest note and how many cents you are from it; Nearest note snaps to it, and Play a note jumps to any note and octave.

Pick a wave (sine, square, sawtooth, triangle, or white, pink or brown noise), set the Volume, and choose Both, Left only or Right only, or move the Balance slider. Copy link copies an address with your frequency, wave and volume, so the same tone opens for someone else. Your settings are also kept on this device for next time.

Keyboard: Space plays and stops, ↑ and ↓ change the frequency by 1 Hz, add Shift for a semitone or Alt (Option on a Mac) for 0.1 Hz, and Page Up or Page Down move an octave.

Start quiet. High levels and high frequencies can damage hearing and speakers. Turn your device down before you play, then raise it slowly.

What Hz means

Hz (hertz) counts cycles per second, and a Hz generator lets you hear any number you type. A 440 Hz tone makes the air vibrate 440 times each second. Double the frequency and you hear the same note one octave higher; halve it and you go an octave lower. Each octave is split into 12 semitones, and each semitone into 100 cents, so a semitone step multiplies the frequency by the twelfth root of 2 (about 1.0595).

Here are the A notes across the octaves and middle C, worked out from the same note engine the tool uses:

The range of human hearing

The commonly stated range of human hearing is 20 Hz to 20,000 Hz. The top of that range shrinks through life, usually starting at around age eight, so many adults stop hearing the highest tones on this page. Our ears are most sensitive between 2,000 and 5,000 Hz. Speakers have limits too: small phone and laptop speakers may play nothing at all for a very low tone.

What a tone generator is good for

Tuning by ear. Play A4 at 440 Hz and match a string to it, or listen for beats against the reference. For tuning with a needle, use the online tuner.

Speaker and headphone checks. Use Left only and Right only to confirm the channels are wired the right way round, and a slow sweep to hear where a small speaker runs out of bass or starts to rattle.

A rough hearing check. A sweep or a few high tones show roughly where your hearing tops out on your own equipment. It is not a medical hearing test: headphones, speakers and volume all change the result, so see a hearing professional for a real test.

Science and music lessons. Show how pitch follows frequency, how two close tones beat, and how waveforms sound different. To see the pitch of your own voice, try the pitch detector, or check how small a pitch difference you hear with the tone deaf test, or try naming notes with no reference on the perfect pitch test.

Sine, square, sawtooth, triangle and noise

Set to sine, it works as a sine wave generator: a sine wave is one frequency and nothing else, the cleanest test tone. The other waves add harmonics, which are whole-number multiples of the frequency you set (2 times, 3 times and so on), and those harmonics give each wave its color.

• Square: only the odd harmonics (3, 5, 7...), each at 1/n of the level of the first. Hollow and buzzy.
• Sawtooth: every harmonic, each at 1/n. The brightest of the four.
• Triangle: odd harmonics again, but at 1/n², so they fade fast. Softer, close to a sine with a little edge.

Noise has no single pitch. White noise has equal energy at every frequency and sounds like a hiss. Pink noise loses energy as the frequency rises, with equal energy in each octave, so it sounds deeper and more even than white noise. Brown noise drops off faster still and sounds like a low rumble.

Sweeps, beats and chords

Open Sweep below the tool, set From, To and Time, choose Logarithmic (equal time per octave, the usual choice for audio) or Linear (equal Hz per second), turn on Loop to repeat it, then press Play sweep. Under More tones, add up to three extra tones, each with its own frequency, wave and volume. Beats (+3 Hz) adds a tone 3 Hz higher, so you hear the level pulse three times a second. Major chord and Minor chord add the third and fifth above the main tone. For real instrument sounds, play the online piano.

More for sound check: Mic Test · Sound Test · Speaker Test · Headphone Test · Left Right Test · Bass Test · Surround Sound Test · Audio Delay Test · Speaker Cleaner

Questions

More tools

• Tuner
• Pitch Detector
• Online Piano
• Tone Deaf Test
• Perfect Pitch Test
• Metronome