Play a pure tone from 1 to 22,000 Hz. Pick the waveform, sweep a range, or play two tones for headphones.
An online tone generator plays a pure, steady sound at the frequency you type, and this one covers 1 to 22,000 Hz with four waveforms. A sine wave is the plainest tone, with one frequency and nothing else. A square wave sounds hollow and buzzy, a sawtooth sounds bright and harsh, and a triangle sits between sine and square. People use a tone generator to tune an instrument by ear, with 440 Hz as the A above middle C, to check which frequencies a speaker or headphone can reproduce, to find a rattle in a room, to test a subwoofer with 30 to 80 Hz tones, or just to hear what a pitch sounds like. The frequency box takes numbers to two decimals, the slider is logarithmic so low and high pitches get equal room, and the fine buttons move by 1 Hz, 10 Hz or one semitone.
Music is tuned in equal temperament with A4 set at 440 Hz. Each semitone multiplies the frequency by the twelfth root of 2, about 1.0595, so A5 is 880 Hz and middle C (C4) is about 261.63 Hz. The page shows the nearest note and how many cents sharp or flat you are, where 100 cents make a semitone. Type a note name such as A4 or C#5 in the note box to jump to it. The Note minus and Note plus buttons move one semitone at a time, and the common tone chips jump to 50 Hz, 440 Hz, 1000 Hz and higher. The channel buttons send the tone to the left, the right or both speakers, which is handy for checking that your headphones are wired the right way round.
Sweep mode glides from a start frequency to an end frequency over 1 to 300 seconds. A logarithmic sweep covers the same number of octaves each second, which matches how pitch is heard. A linear sweep covers the same number of hertz each second. Two tones plays two frequencies together, and when they are close, say 440 and 444 Hz, you hear a slow pulsing at the difference, here 4 beats a second. Binaural beat mode plays the carrier in your left ear and the carrier plus the beat frequency in your right ear, from 1 to 40 Hz apart. It needs stereo headphones, because the beat is made in your head rather than in the air. The tool makes no claim that binaural beats change mood, focus or health.
The volume starts at 20 percent, which is quiet, because a steady pure tone can feel much louder than music at the same level, and high pitches can be painful. Raise it slowly, and take headphones off while you set the level. Square and sawtooth waves carry more energy than sine at the same setting. What you hear depends on your device: phone and laptop speakers barely reproduce anything below 100 Hz, and few speakers play above 18 kHz. A sound card with a 44.1 kHz sample rate can only play up to 22,050 Hz, and the page warns you if a frequency is out of reach. This is a sound source, not a calibrated instrument or a hearing test. Your settings are saved in this browser, nothing is uploaded, and the page counts visits with Google Analytics, never what you played.
This one plays 1 Hz to 22,000 Hz. Whether you can hear it depends on your speakers or headphones: laptop speakers rarely go below 100 Hz, and most devices drop off above 16 to 18 kHz.
It is the default. Press Play, or type 440 in the frequency box. 440 Hz is the note A4, the tuning reference used by orchestras and tuners. Type A4 in the note box to jump back to it.
A sine wave is a pure tone with one frequency. A square wave adds odd harmonics and sounds hollow. A sawtooth adds all harmonics and sounds bright. A triangle has weak odd harmonics, so it sounds soft, between sine and square.
Choose Binaural beat, set a carrier such as 200 Hz and a beat from 1 to 40 Hz, and wear stereo headphones. The left ear gets 200 Hz and the right gets 200 plus the beat. Keep the volume low. The tool makes no health claims.
Your speakers may not reproduce it. Small speakers lose output below about 100 Hz. Also a sound card at 32 kHz cannot play 16 kHz or higher, and the page shows a message if a frequency is above half the sample rate.
Keep the volume low. The page starts at 20 percent and warns above 60. A steady pure tone can be harsher than music at the same level, and loud sound can damage hearing. Stop if a tone is painful.