--- title: "Online Tone Generator: Sine, Sweep, Noise, Channel Test" description: "Free online tone generator: sine waves 20 Hz-20 kHz, noise colors, sweeps, plus a channel and polarity test. A signal generator in your browser, no install." url: "https://theaudiostuff.com/tools/signal-generator/" type: "website" author: "Jakub Charkiewicz" --- > Markdown rendering of https://theaudiostuff.com/tools/signal-generator/ > Canonical URL to cite: https://theaudiostuff.com/tools/signal-generator/ > Generated from the published page. Text and links only; see the HTML for layout. Breadcrumb: [Home](https://theaudiostuff.com/) > [Tools](https://theaudiostuff.com/tools/) > Online Tone Generator # Online Tone Generator Sine waves, white noise, pink noise, brown noise, blue noise, violet noise, frequency sweeps, and polarity check. All generated in real time by the Web Audio API - no files, no downloads. Identical to what professional audio generators output. **Tip:** start at low volume. The 1 kHz sine wave at -12 dBFS is the standard reference test signal. Pink noise at -18 dBFS is the level-matching reference most calibration tools use. (New to dBFS? There's a one-line explainer under the Level slider.) My presets Save signal configurations (calibration tones, sweep settings, custom noise levels) for one-click recall. Hz -12 dBFS dBFS = decibels below digital full scale. 0 dBFS is the loudest a file can be; -12 dBFS is a safe testing level. -18 dBFS Sweep range Hz Hz Duration & mode sec -12 dBFS Generates a short click pulse - listen in both channels at once. Correctly-connected speakers produce one "pop" with bass energy; reversed polarity sounds thin and bass-anaemic. Live signal monitor ## About the noise colors {#noise-colors} - **White noise**: Equal energy at every frequency. Sounds like TV static or heavy rain. Used for masking ambient noise and speaker frequency response testing. - **Pink noise**: Equal energy per octave (-3dB/octave slope). Perceptually "flat" - the closest noise to music in spectral balance. The standard for room acoustic measurements. - **Brown noise**: -6dB/octave slope. Heavy bass emphasis - often described as a waterfall or deep rumble. Very popular for sleep and focus. - **Blue noise**: +3dB/octave slope. High-frequency emphasis - sounds bright and hissy. Used in dithering algorithms to push quantization noise out of the audible band. - **Violet noise**: +6dB/octave slope. Extreme treble emphasis. Rarely used in audio but appears in some dithering applications and tinnitus research. ## Frequency landmarks worth remembering {#ref-sig-title} Pin these tones to your ear. Sweep the generator above between any two of them and you start to hear the structure of the audible band - and where every "warm," "bright," "muddy," or "harsh" complaint actually lives. | Frequency | Landmark | What it does in music | | --- | --- | --- | | 20 Hz | Lower hearing limit | Felt rather than heard. Pipe organ pedal, EDM sub. | | 41.2 Hz | Bass guitar low E | The bottom of most rock recordings. | | 50 / 60 Hz | Mains hum | Ground loop frequency. Listen for it on quiet passages. | | 82.4 Hz | Guitar low E | Body / chest of the rhythm guitar. | | 200-250 Hz | "Muddy" zone | Boomy male vocals; cup/proximity effect on mics. | | 440 Hz | Concert pitch A | Tuning standard. Where instruments meet. | | 1 kHz | Reference tone | SPL meter calibration. Voice intelligibility centre. | | 3-4 kHz | Ear sensitivity peak | Fletcher-Munson minimum. Sibilance starts here. | | 6-10 kHz | Sibilance band | "S" and "T" consonants. Bright cymbals. | | 15 kHz | Adult upper limit | Most adults can't hear above this; kids reach 18 kHz+. | | 20 kHz | Theoretical upper limit | The Nyquist target. Few adults hear it cleanly. | ## What test tones and noise are for {#tprimer-title} A pure sine wave contains exactly one frequency, which makes it the cleanest way to ask a system a single question: can it reproduce this, at this level, without adding anything. Anything you hear that is not the tone - a buzz, a rattle, a second pitch - was added by the room or the equipment. Noise asks a broader question. White noise has equal energy in every hertz, which makes it sound bright because the upper octaves each contain far more hertz than the lower ones. Pink noise corrects for that with a 3 dB per octave tilt, giving equal energy per octave, which is why it is the standard signal for level matching and room measurement. Sweeps combine both approaches by walking a tone through the range, which reveals where a response dips, where a resonance rings, and where a driver or a cabinet starts to buzz - things a static tone at one frequency would walk straight past. ### The ideas behind the controls {#tprimer-ideas} - **White noise**: Equal energy per hertz. Sounds hiss-like and treble-heavy because high octaves are much wider in hertz than low ones. - **Pink noise**: Equal energy per octave, a 3 dB per octave downward tilt. The reference signal for level matching and room measurement. - **Brown noise**: A steeper 6 dB per octave tilt. Bass-dominant, and useful for checking low-frequency behaviour and rattles. - **Polarity check**: A test that reveals whether both channels push in the same direction. Reversed polarity thins the bass and destroys the centre image. ### Common mistakes {#tprimer-mistakes} - Running test tones at high level. A sustained sine puts far more sustained energy into a tweeter than music ever does. - Judging system response by ear from a sine sweep in a room. What you are mostly hearing at low frequencies is the room, not the speaker. - Using white noise where pink is meant. It over-weights the treble and will lead you to level-match wrongly. - Confusing polarity with channel swap. One collapses the image, the other just moves it. ### What this tool cannot tell you {#tprimer-limits} - Everything between the tone and your ears colours it: the browser audio path, the DAC, the amplifier, the transducer and the room. What you hear is the chain, not the generator. - It is a listening aid, not a measurement instrument. Judging frequency response by ear from tones is unreliable, because a level difference reads as a quality difference. ## Audio signal generator FAQ. {#signal-faq-title} What you can test with sines, sweeps, and the noise colours - plus safe SPL ranges for measurement work. 1. ### What can I do with an online tone generator? {#signal-faq-what-can-i-do-with-an-online-tone} Test speakers and headphones with sine sweeps, room behaviour with pink noise, channel matching with mono-vs-stereo tones, polarity with a polarity-check signal, and DAC linearity with low-level test tones. It is the swiss army knife of audio measurement: frequency response, distortion, phase, channel balance, all from one page. 2. ### What is the difference between white, pink, brown, blue, and violet noise? {#signal-faq-what-is-the-difference-between-white-pink-brown} White noise has equal energy per Hz; pink noise has equal energy per octave (the standard for room measurement); brown (Brownian) drops 6 dB per octave for deep low-end testing; blue rises 3 dB per octave; violet rises 6 dB per octave. Pink and brown are the most useful for audio work; the others appear in DSP testing and synth design. 3. ### How loud should test tones be when measuring speakers? {#signal-faq-how-loud-should-test-tones-be-when-measuring} Start at -20 dBFS in the player and adjust the amplifier so a 1 kHz sine measures around 80 dB SPL at the listening position. Sweeps and pink noise can stay at the same RMS. Never go above 95 dB SPL for sustained tones. It is not pleasant for ears or speakers. 4. ### Does the tone generator work for ear training? {#signal-faq-does-the-tone-generator-work-for-ear-training} It can, but the dedicated frequency-training tool is built for that purpose with adaptive difficulty and scoring. Use the tone generator when you need a specific tone or sweep on demand; use the trainer when you want guided practice and progress tracking. ## Shopping the gear behind the math? - [Best Budget Headphones](https://theaudiostuff.com/guides/best-budget-headphones/) - [Headphones reviews](https://theaudiostuff.com/reviews/headphones/) - [Speakers reviews](https://theaudiostuff.com/reviews/speakers/) - [HIFIMAN HE1000se Scored 9.3 out of 10](https://theaudiostuff.com/reviews/hifiman-he1000se/) - [HIFIMAN Arya Organic Scored 9.2 out of 10](https://theaudiostuff.com/reviews/hifiman-arya-organic/) - [HIFIMAN Arya Unveiled Scored 9.1 out of 10](https://theaudiostuff.com/reviews/hifiman-arya-unveiled/) - [HIFIMAN Arya Organic vs HE1000se](https://theaudiostuff.com/compare/hifiman-arya-organic-vs-hifiman-he1000se/) - [HIFIMAN Arya Unveiled vs HE1000se](https://theaudiostuff.com/compare/hifiman-arya-unveiled-vs-hifiman-he1000se/) ## You might also use these tools {#rt-title} - [Analyzer **Is this file really hi-res?** FLAC & Hi-Res Audio Checker Drop any audio file and see its real frequency content via FFT spectrogram. 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