Tone Generator, Tuner & Hearing Test
Generate pure sine, square, sawtooth, and triangle tones at any frequency, tune an instrument with a microphone pitch detector, and test the upper limit of your hearing — all in your browser with the Web Audio API.
How to Use
- In the Tone Generator, pick a waveform, drag the frequency slider (or type an exact Hz value), set a safe volume, then press Play. Audio starts only after you click.
- Adjust frequency, waveform, and volume while a tone is playing — the changes apply live without restarting.
- In the Tuner, click "Start tuner" and allow microphone access. Play or sing a note and read the detected frequency, nearest note, and how many cents sharp or flat you are.
- In the Hearing Test, lower your volume first, then step the frequency up toward 20 kHz to find the highest pitch you can still hear.
- Press Stop (or stop the tuner) when you are done to release the audio context and microphone.
How tones, pitch & tuning work
A pure tone is a single frequency — a sine wave that repeats a fixed number of times per second, measured in hertz (Hz). The more cycles per second, the higher the pitch you hear. A square, sawtooth, or triangle wave has the same fundamental frequency but adds harmonics (whole-number multiples of the fundamental), which is why they sound brighter or buzzier than a sine at the same pitch.
Western music uses equal temperament: the octave is split into twelve equal steps, so each semitone is the previous frequency multiplied by the twelfth root of two (about 1.05946). Pitch is anchored to A4 = 440 Hz. To find the note for any frequency, the tuner computes 12 × log₂(f / 440) + 69 to get a MIDI number, rounds it to the nearest note, and reports the leftover as cents (hundredths of a semitone) so you know how sharp or flat you are.
The tuner finds pitch with autocorrelation: it slides a copy of the recorded waveform against itself and measures the delay at which they line up best. That delay is the period of the sound; the sample rate divided by the period gives the frequency. It works well on steady, single-note sounds like a plucked string or a sung vowel.
Reference card
Safety: pure tones can be fatiguing. Start quiet, raise the volume only as needed, and never crank the level to hear a very high or very low frequency. This hearing check is a rough demonstration, not a medical audiogram.
About the Tone Generator, Tuner & Hearing Test
Need a hand with image, audio and file tasks? The Tone Generator, Tuner & Hearing Test does the work for you — free, and right here in your browser. Generate pure sine, square, sawtooth, and triangle tones at any frequency, tune an instrument with a microphone pitch detector, and test the upper limit of your hearing — all in your browser with the Web Audio API.
How it works
Enter what you have and read the result as it updates live. It all runs on your own device, so it is quick and private, with nothing to install.
Want the deeper story? The Knowledge Base explains the ideas behind the tools in more detail.
Frequently Asked Questions
What is a tone generator used for?
A tone generator plays a pure, steady tone at a frequency you choose. People use it to test and set up speakers, headphones, and subwoofers, to find rattles and resonances in a room, as a reference pitch for tuning instruments, for science and physics demonstrations, and for hearing experiments. Because the tone is a clean waveform with no music or noise, it isolates a single frequency so you can hear and measure it precisely.
Is it safe for my ears? How loud should the volume be?
Start with the volume low and raise it only as needed. Sustained pure tones — especially loud high-frequency or low-frequency tones — can be uncomfortable and, at high levels over time, damaging. This tool caps the gain and starts at a low default, but your system volume still matters: turn your device and amplifier down before playing, and never push the volume to find a tone you cannot otherwise hear. If a tone hurts, stop immediately.
How does the tuner detect pitch?
The tuner captures audio from your microphone and runs autocorrelation on the raw waveform. It copies a window of samples, measures how well the signal lines up with a delayed copy of itself, and finds the delay (lag) that gives the strongest match. That lag is the period of the sound; dividing the sample rate by it gives the fundamental frequency. The note name and cents-off come from comparing that frequency to equal-tempered pitches anchored at A4 = 440 Hz.
What is a hearing test and what does this one measure?
This is a simple high-frequency hearing screen, not a medical audiogram. It plays a tone you can sweep upward in frequency so you can find the highest pitch you can still hear. Young people often hear up to roughly 18–20 kHz; that upper limit drops gradually with age and noise exposure. It is a fun, rough demonstration — for any real hearing concern, see an audiologist for a proper test.
Is the audio processed locally?
Yes. Everything runs in your browser using the Web Audio API. Tones are synthesized on your device, and the tuner analyses microphone audio locally — nothing is recorded, uploaded, or sent to a server. Microphone access is requested only when you click "Start tuner", and it is released when you stop.
How do I use the Tone Generator, Tuner & Hearing Test?
Simply type your numbers and read the result, which refreshes the instant you change something. There is nothing to submit and nothing to wait for.
Is it free? Does it work without internet?
Yes to both. It is free with no sign-up, and once the page has loaded it keeps working even with no internet.
Where does my data go?
Nowhere — every calculation runs on your own device. Nothing you enter is uploaded, logged, or stored.
Common Use Cases
Test speakers & headphones
Sweep a clean tone to check channel balance, find buzzes and rattles, and verify your subwoofer reaches low frequencies.
Tune an instrument
Use the reference tone or the microphone tuner to bring a guitar, violin, or voice into pitch against A4 = 440 Hz.
Check your hearing range
Step the frequency upward to find the highest pitch you can hear — a quick demonstration of high-frequency hearing loss with age.
Science & classroom demos
Show waveforms, beats, octaves, and equal temperament with exact frequencies for physics and music lessons.
Tinnitus pitch matching
Sweep the generator to find the frequency that matches a ringing in your ears, a common first step before discussing it with a professional.
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