Tone Generator
Play any frequency from 20 Hz to 20 kHz in your browser. Pick a waveform, run a sweep, mix binaural beats, jump to musical notes or Solfeggio presets, and run a guided hearing check — all synthesized live with the Web Audio API, nothing uploaded.
- Nearest note
- A4
- Wavelength (20°C)
- 0.7805 m
- Period
- 2.2727 ms
- Note
- A4
- MIDI
- 69
Equal temperament, A4 = 440 Hz. Uses the same waveform, volume and pan as the Tone tab.
Ready.
A logarithmic sweep moves at a constant musical rate (equal semitones per second); a linear sweep moves at a constant Hz per second and sounds slow at the bottom, fast at the top.
- Left channel
- 435 Hz
- Right channel
- 445 Hz
- Perceived beat
- 10 Hz
Use stereo headphones: each ear gets a slightly different tone and your brain perceives the difference as a slow pulse. Reported effects are subjective; treat this as an interesting listening experiment, not therapy.
One-tap presets for the nine commonly listed Solfeggio tones. Plays with your current waveform and volume.
A guided walk through 9 test frequencies. For each one: play it, then mark whether you heard it. This is a curiosity experiment, not a hearing diagnosis — only a qualified audiologist can test your hearing.
Press start. Keep volume at your calibrated comfortable level.
| Frequency | Result |
|---|
Shortcuts (Tone tab): Space play/stop, ←→ ±1 Hz, Shift+arrows ±10 Hz, Ctrl+arrows ±100 Hz.
What is sound frequency?
Sound is air pressure waving up and down. Frequency counts how many of those waves pass per second, measured in hertz (Hz). A 440 Hz tone wiggles the air 440 times every second; a 40 Hz tone only 40 times. Higher frequency sounds higher in pitch: double the frequency and you go up exactly one octave — 220 Hz, 440 Hz and 880 Hz are all the note A, three octaves apart.
Each wave also has a period (T = 1/f, the seconds per wave) and a wavelength (λ = c/f, how long one wave is in the air). At room temperature sound travels at about 343 m/s, so a 440 Hz tone has a wavelength of roughly 0.78 metres — about the length of a guitar. A 20 Hz rumble stretches over 17 metres, which is why sub-bass feels more like pressure than pitch.
Waveforms: why the same pitch can sound different
Pitch is set by frequency, but timbre — the character of the sound — is set by the waveform, the shape of each wave. Every periodic wave is a stack of a fundamental plus harmonics (whole-number multiples of the fundamental), and each shape stacks them differently:
| Waveform | Harmonics | Sounds like | Use it for |
|---|---|---|---|
| Sine | Fundamental only — a pure tone | Soft, clean, flute-like | Hearing checks, tuning references, the gentlest test tone |
| Triangle | Odd harmonics, fading fast (1/n²) | Mellow, slightly hollow | A softer alternative to square for long listening |
| Square | Odd harmonics, fading slowly (1/n) | Hollow, buzzy, clarinet-like | Testing how speakers handle harmonics; retro game sounds |
| Sawtooth | All harmonics, fading slowly (1/n) | Bright, harsh, buzzy | The richest test signal — reveals rattles and distortion fast |
Try this: play 440 Hz as a sine, then switch to sawtooth without touching anything else. Same pitch, completely different sound — that difference is the harmonic stack. Cheap speakers and laptop drivers often distort on square and sawtooth waves first, which makes them great diagnostic signals.
Human hearing range
Young, healthy ears hear roughly 20 Hz to 20 kHz — ten octaves. Sensitivity is not flat: we hear best around 2–5 kHz (where speech lives) and poorly at the extremes, which is why a 30 Hz tone needs far more volume than a 1 kHz tone to sound equally loud. High-frequency hearing fades with age as the hair cells in the inner ear wear down — a gradual, normal process:
| Age band | Typical upper limit |
|---|---|
| Under 20 | ~19,000 Hz |
| 20s | ~17,600 Hz |
| 30s | ~16,100 Hz |
| 40s | ~14,200 Hz |
| 50s | ~12,100 Hz |
| 60+ | ~9,900 Hz |
Population averages for orientation only — individuals vary widely, and loud-noise exposure lowers these numbers. This page cannot diagnose hearing loss.
Why digital audio tops out: the Nyquist limit
Digital audio stores snapshots of the wave 44,100 times per second (the CD standard). A theorem by Nyquist and Shannon proves you need at least two snapshots per wave cycle to capture a frequency, so 44,100 snapshots can represent frequencies up to 22,050 Hz — the Nyquist limit, comfortably above the 20 kHz edge of hearing. That is why this generator allows frequencies up to 22,050 Hz and no higher: anything above it cannot exist in standard digital audio. (Your sound card may resample to 48 kHz internally, but the math is the same idea.)
Musical notes and frequency
Modern instruments tune to equal temperament: every semitone is the twelfth root of two apart (a ratio of about 1.0595), and the note A4 is fixed at 440 Hz. The frequency of any MIDI note is f = 440 × 2(n−69)/12. Middle C (C4) is MIDI 60, so f = 440 × 2−9/12 ≈ 261.63 Hz.
| Note | Frequency | Note | Frequency |
|---|---|---|---|
| A0 | 27.50 Hz | C5 | 523.25 Hz |
| C2 | 65.41 Hz | A5 | 880.00 Hz |
| A2 | 110.00 Hz | C6 | 1046.50 Hz |
| C4 (middle C) | 261.63 Hz | A6 | 1760.00 Hz |
| A4 (tuning pitch) | 440.00 Hz | C8 | 4186.01 Hz |
Typical frequency ranges of instruments and voices
| Source | Fundamental range |
|---|---|
| Pipe organ (largest pipes) | 16 Hz – 8 kHz |
| Piano | 27.5 Hz (A0) – 4,186 Hz (C8) |
| Bass guitar | 41 Hz – 350 Hz |
| Cello | 65 Hz – 660 Hz |
| Human voice (bass – soprano) | ~80 Hz – ~1,100 Hz |
| Guitar (standard tuning) | 82 Hz (E2) – 1,318 Hz (E6) |
| Violin | 196 Hz (G3) – 3,520 Hz (A7) |
| Flute | 262 Hz (C4) – 2,093 Hz (C7) |
| Piccolo | 523 Hz – 5,000 Hz |
Fundamentals only — harmonics extend far above these ranges, which is why a violin still sounds like a violin through a tweeter.
Worked examples
Practical tips
- Calibrate at 1 kHz. Play a 1,000 Hz sine and set a comfortable volume. Keep that level for every other frequency — if you cannot hear 30 Hz or 17 kHz at that level, the answer is your ears and speakers, not the volume knob.
- Sine for ears, sawtooth for gear. Use sine waves for hearing checks and pitch references (no harmonics to confuse you); use sawtooth or square to stress-test speakers, because their harmonics expose rattles and distortion.
- Log sweep beats linear sweep for speaker testing: equal time per octave instead of equal time per hertz.
- Test one ear at a time with the stereo pan slider to spot left/right differences.
- Share exact tones with the share-link button — it encodes mode, frequency and waveform in the URL.
- Give it a fade. Starting and stopping a tone instantly can click; the short fade envelope is on by default for that reason.
- Headphones for binaural, speakers are fine for the rest. Binaural beats need isolated left/right channels to work at all.
Frequently asked questions
What is an online tone generator?
An online tone generator plays a pure audio tone at any frequency you choose, from 20 Hz up to 20,000 Hz, directly in your browser using the Web Audio API. Pick a frequency, press play, and the tone is synthesized live on your device - nothing to install, no account, nothing uploaded. Typical uses: tuning an instrument, testing speakers or headphones, exploring your hearing range, or simply hearing what a specific frequency sounds like.
What frequencies can this tone generator play?
The input accepts 1 Hz to 22,050 Hz. In practice, human hearing spans about 20 Hz to 20,000 Hz: below 20 Hz most people feel pressure rather than pitch, and above 20,000 Hz almost nobody hears anything. The 22,050 Hz ceiling is the Nyquist limit of 44.1 kHz digital audio - frequencies above it cannot exist in standard digital sound, so the generator does not offer them.
Which waveform should I choose: sine, square, triangle or sawtooth?
Use sine for hearing checks and pitch references: it is a pure tone with no harmonics, so what you hear is exactly the frequency you set. Triangle is a softer, mellower alternative. Square adds strong odd harmonics and sounds buzzy and hollow. Sawtooth contains every harmonic and sounds the brightest and harshest, which makes it the best diagnostic signal - it exposes speaker rattles and distortion that a sine wave would hide.
What are Solfeggio frequencies?
The nine presets on the Solfeggio tab - 174, 285, 396, 417, 528, 639, 741, 852 and 963 Hz - are a set of tones with a long history in music and sound lore. Claims about special effects of these exact frequencies are not scientifically established; they are included here as convenient one-tap presets for listening experiments.
How do binaural beats work?
Each ear receives a slightly different tone through stereo headphones - for example 435 Hz left and 445 Hz right with a 440 Hz carrier and a 10 Hz beat setting. Your auditory system perceives the 10 Hz difference as a slow pulse that exists in neither channel alone. Reported effects are subjective and the research evidence is limited, so treat it as an interesting listening experiment, not therapy. Headphones are required: over loudspeakers the two channels mix in the air and the effect collapses.
Can I use this to test my hearing?
The Hearing test tab walks you through 9 frequencies from 125 Hz to 16,000 Hz as a curiosity experiment: for each tone you mark whether you heard it at your current volume. It is educational only and not a medical device - only a qualified audiologist can assess hearing. Calibrate with a comfortable 1,000 Hz tone first and do not raise the volume to chase very low or very high tones.
How do I tune a guitar with a tone generator?
Play a 440 Hz sine on the Tone tab and pluck your A string at the same time. If the string is at 442 Hz you will hear a slow wah-wah pulsing 2 times per second: the beat rate equals the frequency difference, |440 - 442| = 2 Hz. Loosen the string and the pulsing slows; when it disappears the string is at 440 Hz. A 442 Hz string is only 7.85 cents sharp, so beats reveal errors your ear cannot name directly.
What is a frequency sweep and what is it used for?
A sweep glides the tone continuously from a start frequency to an end frequency, for example 40 Hz to 16,000 Hz over 15 seconds. It is the fastest way to test speakers and headphones: listen for where the sound gets quiet (driver roll-off), rattles (something loose), or turns harsh (distortion). Choose the logarithmic curve for an even musical pace - equal time per octave instead of equal time per hertz.
Why does the same frequency sound different on different speakers?
Every speaker has a frequency response: it reproduces some frequencies louder and others quieter, and small drivers typically fade below 150 to 200 Hz. Harmonics matter too - a sawtooth wave asks the speaker to reproduce many harmonics at once, so distortion and rattles show up on complex waves long before they appear on a pure sine. Room acoustics add their own peaks and dips on top.
Is it safe to play very low or very high frequencies?
Start with the volume low and calibrate with a comfortable 1,000 Hz tone. Human hearing is least sensitive below about 30 Hz and above about 10,000 Hz, so the temptation is to crank the volume to hear those extremes - do not. Loud levels at any frequency can damage hearing, and strong low-frequency signals can overdrive small speaker drivers. If you cannot hear a tone at your calibrated level, that information about your ears and gear is the result.
What is the Nyquist frequency?
Digital audio stores snapshots of the sound wave. The Nyquist-Shannon theorem proves you need at least two snapshots per wave cycle to capture a frequency, so audio sampled 44,100 times per second - the CD standard - can represent frequencies up to 22,050 Hz. That ceiling sits just above the 20,000 Hz edge of human hearing, which is why 44.1 kHz became the standard and why this generator tops out at 22,050 Hz.
Can I download the tone as an audio file?
Yes. Set your frequency and waveform on the Tone tab, then press Download 5s WAV. The tone is rendered offline in your browser and saved as a standard 16-bit WAV file that plays in any audio software - useful as a test signal or a ringtone source.
How is this different from a beat frequency calculator?
This page produces sound: it plays tones through your speakers or headphones. A beat frequency calculator does math instead - given two frequencies it computes their interference beat rate, f_beat = |f1 - f2|, plus the beat period and the missing-frequency solutions. The two tools complement each other: generate a 440 Hz reference here, then compute expected beat rates there.
Related tools
Computing interference between two tones? Try the Beat Frequency Calculator (fbeat = |f₁ − f₂|). Building a hardware oscillator instead of a browser tone? See the 555 Timer Astable Calculator.
Free tool by NRTechStudio