Tone Generator

Type a frequency, press Play, and your speakers or headphones produce that exact tone. Anything from 1 Hz to 22,000 Hz works, as a sine, square, sawtooth or triangle wave. Adjust it while it plays — the log-scale slider for big moves, ±1 Hz and semitone buttons for fine ones, or ↑/↓ inside the frequency field (Shift for 10 Hz, Alt for 0.1 Hz). The nearest musical note and its offset in cents are shown as you go, and the Musical note list jumps straight to any note from C0 to B8.

Everything is synthesised live by your browser's Web Audio engine — there are no audio files, nothing is downloaded, and nothing leaves your device. Starting and stopping fade over a few milliseconds, so there is no click or pop, and changes to frequency, volume and balance glide rather than jump.

Three modes

• Tone — a steady tone at one frequency, with presets for common test frequencies: 50/60 Hz mains hum, 440 Hz concert A, 1 kHz reference, and high tones for hearing checks.
• Sweep — glides from a start to an end frequency over the time you set. Logarithmic spends equal time on each octave, which is how we hear pitch and how speakers are measured; Linear spends equal time on each hertz, so it races through the bass. Turn on Repeat for a continuous sweep.
• Noise — white (equal energy at every frequency, a bright hiss), pink (equal energy per octave, the standard signal for balancing speakers and rooms) and brown (a deep rumble many people use for focus or sleep).

Speaker and headphone test

Choose Left only or Right only to check that each channel is wired and labelled correctly, or use the balance slider to pan smoothly between them. A low sweep reveals buzzing panels and rattles; a high one shows where your tweeters — or your ears — stop.

Common uses

• Check left/right channels and wiring on new speakers, headphones or a car stereo
• Find rattles, buzzes and room resonances with a slow bass sweep
• Tune an instrument or test a tuner against an exact reference pitch
• Get a rough idea of your upper hearing limit with high-frequency tones
• Mask tinnitus or background noise with pink or brown noise

Example

Sweep · 20 Hz → 200 Hz · 30 s · logarithmic

Rattle at ≈ 63 Hz

A slow log sweep through the bass makes loose trim, a buzzing desk or a room mode stand out at one frequency. Switch to Tone and park on that frequency to find the culprit.

Limitations

• Your hardware sets the real range. Phone and laptop speakers rarely reproduce much below 100–150 Hz, and most headphones fade below 20 Hz; output stops at half your device's sample rate (usually 22,050 or 24,000 Hz).
• This isn't a calibrated hearing test — the level depends on your device volume and headphones. See an audiologist for a proper audiogram.
• The waveforms are matched for loudness, so a square wave plays at a lower peak level than a sine.
• Some browsers pause audio in background tabs on phones; keep the page open while it plays.

How do I generate a specific frequency tone?

Type the frequency into the Frequency field (for example 432 or 12.5k) and press Enter, then press Play or the Space bar. Use the slider for large changes and the ±1 Hz, semitone and octave buttons — or ↑/↓ in the field — to fine-tune while it plays.

What volume should I use?

Start at the default 25% with your device volume low, then turn up gradually. Pure tones sound louder and are more tiring than music at the same level, and very high or very low tones can be loud even when you can barely hear them — never raise the volume to hunt for an inaudible tone, especially on headphones.

What is the difference between sine, square, sawtooth and triangle waves?

A sine wave is a single pure frequency. Triangle adds faint odd harmonics and sounds a little brighter, square adds strong odd harmonics for a hollow, buzzy tone, and sawtooth contains every harmonic, giving the brightest, harshest sound. Use sine for testing and hearing checks.

What is the difference between white, pink and brown noise?

White noise has equal energy at every frequency, so it sounds like a bright hiss. Pink noise has equal energy per octave and sounds more balanced — it's the standard test signal for speakers and rooms. Brown noise rolls off even faster towards the treble and sounds like a deep, steady rumble.

How do I test left and right speakers or headphones?

Set Channel to Left only and press Play — sound should come only from the left side — then switch to Right only. If they are reversed, the speakers or headphones are wired or worn the wrong way round. The balance slider pans smoothly between the two.

What is the highest frequency I can hear?

Young people can typically hear up to about 17–20 kHz, and the limit falls with age; many adults stop around 12–15 kHz. Play a high tone at a modest volume and lower the frequency until you hear it. Remember the result depends on your speakers too, and it isn't a medical hearing test.

Linear or logarithmic sweep — which should I use?

Logarithmic for almost everything: it spends equal time on each octave, matching how we hear pitch and how speaker frequency responses are plotted. A linear sweep spends equal time per hertz, so 20 Hz to 20 kHz rushes through the bass in the first second.

Why can't I hear very low frequencies?

Below about 20 Hz is infrasound, which humans feel more than hear, and most small speakers can't move enough air to reproduce bass below 80–150 Hz at all. Try headphones or a subwoofer for low tones — and keep the volume moderate, since you may see a woofer move before you hear anything.