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About this tool
Play pure sine, square, sawtooth or triangle tones from 1 Hz to 22 kHz, mix up to four, run frequency sweeps and binaural beats.
This online tone generator creates sound with your browser's Web Audio API: an oscillator produces a sine, square, sawtooth or triangle wave at the exact frequency you set, from 1 Hz to 22,000 Hz, and every volume change is ramped over a few milliseconds so tones start and stop without clicks. Set the pitch with a logarithmic slider, a number box with ±1 and ±0.1 Hz nudges, or a musical note picker. Layer up to four tones with their own level and left/right balance, sweep between two frequencies, or play binaural beats. No audio files are downloaded and nothing is uploaded — the sound is calculated on your device.
Open Online Tone Generator on AltFTool — it loads instantly in your browser.
Pick a preset such as 440 Hz (A4), 1 kHz or 17.4 kHz mosquito, or type a value into Frequency (Hz) and use the −1, −0.1, +0.1, +1, ÷2 and ×2 buttons to fine-tune it.
Choose the Waveform — Sine, Square, Saw or Triangle — and press Play; set Master volume low first and raise it slowly. The live waveform shows what is being played.
Press Add tone to layer up to 4 tones with their own Level and Balance, or switch to the Sweep tab (Start, End, Duration in seconds, Logarithmic or Linear) or the Binaural tab (Carrier plus a Beat frequency from Delta to Gamma).
Use Stop after to end playback automatically after 5 seconds to 30 minutes, and Copy link to this tone to share a URL that opens the same frequency and waveform.
Type any frequency, nudge it by 0.1 or 1 Hz, halve or double it for octaves, or pick a note from C1 to B8 — the nearest note and its offset in cents are always shown.
Each tone has its own waveform, level, mute and left/right balance, so you can build chords, beat patterns or one tone per ear for testing stereo channels.
Sweep linearly or logarithmically once, on loop or up and down over a set number of seconds, or run a carrier tone with a 0.5–50 Hz binaural offset and delta-to-gamma presets.
Copy a link that opens the same frequency and waveform, set an auto-stop timer, and your last tones, volume and sweep settings are kept in this browser.
| Frequency | Name or note | Typical use |
|---|---|---|
| 20 Hz | Lower limit of hearing | Subwoofer extension check; felt more than heard |
| 50 Hz / 60 Hz | Mains hum | Identifying electrical hum and ground loops |
| 100 Hz | Bass | Checking woofers and bass response |
| 261.63 Hz | C4 (middle C) | Music reference |
| 440 Hz | A4 (concert pitch) | Tuning instruments |
| 1,000 Hz | 1 kHz test tone | Level calibration and line testing |
| 3,000 Hz | Peak ear sensitivity zone | Hearing is most sensitive around 2–5 kHz |
| 10,000 Hz | Treble | Tweeter check |
| 17,400 Hz | Mosquito tone | Age-related hearing demonstration |
| 20,000 Hz | Upper limit of hearing | Upper end of the audio band |
Note frequencies assume equal temperament with A4 = 440 Hz. How audible each tone is depends on your speakers or headphones as well as your ears.
A tone generator produces a steady sound at a chosen frequency. Engineers use it to test speakers, amplifiers and cables, musicians use it as a tuning reference, and teachers use it to demonstrate pitch and waveforms. This one runs in the browser: a Web Audio oscillator synthesises the wave in real time, so any frequency between 1 Hz and 22 kHz is available instantly without downloading sound files.
The textbook range is about 20 Hz to 20,000 Hz for a young person with healthy hearing. The upper limit drops with age — many adults over 40 cannot hear much above 14 to 16 kHz. Below 20 Hz, sound is mostly felt as vibration. You can explore your own limits with a sine tone, but a browser test is not a substitute for an audiogram from a hearing professional.
A sine wave is a single pure frequency with no harmonics, which makes it the standard test tone. A square wave adds odd harmonics and sounds hollow and buzzy. A sawtooth contains every harmonic and sounds bright and brassy. A triangle has odd harmonics that fade quickly, so it sounds between a sine and a square. All four share the same fundamental pitch.
440 Hz is the A above middle C (A4) and has been the international concert pitch standard since the mid-20th century; ISO 16 specifies it. Orchestras sometimes tune slightly higher, around 442 Hz. The 432 Hz preset lets you compare the alternative tuning some musicians prefer — the difference is about 32 cents, roughly a third of a semitone.
It can if you play loud tones for long periods. Very low frequencies can push woofers past their limits, and high frequencies can overheat tweeters at high volume. Your ears are most sensitive between 2 and 5 kHz. Start with the master volume low, raise it gradually, and use the Stop after timer for long sessions. The generator ramps volume in to avoid sudden clicks, but it cannot know how loud your system is.
A sweep glides from one frequency to another so you can hear how a speaker, room or pair of headphones responds across the whole range. Rattles, resonant peaks and dead spots stand out as the tone moves. A logarithmic sweep spends equal time on each octave, matching how we hear pitch, while a linear sweep spends most of its time in the treble.
When each ear hears a slightly different pure tone — for example 200 Hz on the left and 210 Hz on the right — the brain perceives a pulsing 'beat' at the 10 Hz difference. It only works with headphones, because each ear must receive only its own tone. Claims about binaural beats changing mood or focus are debated and the research is mixed; treat them as an experiment rather than a treatment.
The so-called mosquito tone is a high-pitched sine wave around 17.4 kHz that most teenagers can hear but many adults cannot, because high-frequency hearing declines with age. Whether you hear it also depends on your speakers or headphones — many laptop speakers barely reproduce frequencies that high — so silence does not necessarily mean you cannot hear it.
Small speakers in phones and laptops usually cannot reproduce much below 150 to 200 Hz, so bass tones may be inaudible or only heard as harmonics. At the top end, your audio device's sample rate sets a hard limit at half its value — 22,050 Hz at 44.1 kHz — and the tool warns you if a tone is above what your device can output.
Yes. The Web Audio context keeps running in a background tab, so you can leave a tone or sweep playing while you work in another window. On phones, locking the screen may pause audio depending on the browser. Use the Stop after timer if you want playback to end on its own.