Frequency generator

Play a steady tone at any frequency, to a hundredth of a hertz, or sweep across the range.

Hz

Nearest note A4, 0 cents

Up to 20 kHz on this device
WaveformSine
Volume-15 dB

How to use the frequency generator

  1. Set a frequency. Type it into the big number, drag the slider, or tap a mark under it, such as 440 or 1k. Decimals work: 261.63, or 261,63.
  2. Press Play or the Space bar. Start with the volume low and raise it slowly.
  3. Fine-tune. −1 and +1 move a hertz; ÷2 and ×2 move an octave. On a keyboard, ← and → step a hertz (with Shift, a tenth), ↑ and ↓ an octave.
  4. Sweep. Switch the card to Sweep, set where it starts and ends and how long it takes, then press Start sweep. It shows where speakers rattle, where bass fades, and where your hearing tops out.

What a tone generator is good for

Find your tinnitus frequency

Match the pitch of the ringing you hear, at low volume, then check the octave above and below with ×2 and ÷2. Write the number down for your audiologist.

Test speakers and subwoofers

A slow sweep from 20 Hz upwards shows where a subwoofer or speaker starts to play, where a cabinet or a loose panel buzzes, and which frequencies the room boosts. Hold any frequency that rattles and look for the source.

Check your hearing range

Put headphones on, switch to Sweep, start at 8 kHz and choose 1 or 2 minutes, then stop when the tone disappears: that is roughly the top of your hearing. A faster sweep overshoots before you can react. Most adults lose the top end with age. It is a rough check, not a hearing test: your equipment's limits are part of the result.

Tune an instrument

Play 440 Hz for concert A, or any reference you need. For named notes and an adjustable A4, use the musical note generator.

Check headphones

Play a low tone to hear whether the drivers rattle, and a high one to find where the treble fades. To check that the left and right sides are wired the right way round, use the left–right headphone test.

Frequency ranges at a glance

What lives where in the audible range, so you know what a tone is testing.

BandRangeWhat you hear there
Sub-bass20–60 HzFelt more than heard: rumble, organ pedals, subwoofers
Bass60–250 HzKick drum body, bass guitar, the warmth of male voices
Low mids250–500 HzFullness, or muddiness when there's too much of it
Mids500 Hz–2 kHzThe core of voices and most instruments; phone speakers live here
Presence2–6 kHzSpeech clarity; hearing is most sensitive around 3–4 kHz
Brilliance6–20 kHzCymbals, air and sparkle; the first range hearing loses with age

Sine, square, triangle or sawtooth?

  • Sine — a pure tone with no harmonics. Use it for tuning, hearing checks and tinnitus matching.
  • Square — strong odd harmonics, hollow and harsh, like an old video game. Good for hearing small speaker defects.
  • Triangle — weak odd harmonics, softer than a square, a little like a flute.
  • Sawtooth — every harmonic at once: buzzy and bright, the raw material of synthesizers.

Listen safely

Start with the volume low and raise it slowly. High frequencies can sound faint and then suddenly piercing, and a steady tone tires your ears faster than music does. Keep sessions short, never play loud tones into headphones you are wearing to sleep, and stop if you hear ringing afterwards. Very loud low tones can damage small speakers too.

Testing a speaker system?
Check every speaker of a stereo, 2.1, 5.1 or 7.1 system, the subwoofer and the wiring polarity.
Test your speakers
Running in new headphones?
A timed program of sweeps, pink noise and rests, with presets by headphone type, and what the measurements actually show.
Open the burn-in tool

Frequently asked questions

Half of your audio output's sample rate: 24 kHz on most computers (48 kHz output), 22.05 kHz at 44.1 kHz. The generator reads it from your device and stops the slider there. Your speakers or earbuds usually give out sooner, often around 16–20 kHz.
Hearing narrows with age: most adults stop hearing somewhere between 14 and 17 kHz, and that is normal. Equipment sets limits too. Phone and laptop speakers barely play anything below 100–200 Hz, and Bluetooth codecs often cut the top off above 16–20 kHz. Try wired headphones before deciding it is your ears.
Keep the volume low and start near the pitch you hear. Drag the slider until the tone sounds closest, then fine-tune with −1 and +1. Check the octave too: press ÷2 and ×2, because a tone one octave away is easy to mistake for the right one. Take the number to an audiologist; a match found online is a starting point, not a diagnosis.
On iPhones before iOS 17, silent mode mutes web audio: turn it off with the ring/silent switch or, on newer models, the Action button or Control Center. Also check the volume buttons, and that no call or other app has taken the audio over. If the tone stops when you lock the screen, unlock and press Play again.
A square wave carries strong odd harmonics at 3×, 5×, 7× the frequency, and a sawtooth carries every harmonic, so they hold more energy where hearing is most sensitive. The generator turns square and sawtooth down a little so switching from sine doesn't jump in loudness.
At a moderate volume and for short periods, yes. Start quiet and raise the level slowly, especially with headphones and high frequencies, which can sound weak until they suddenly don't. Very loud low tones can also damage small speakers. Stop if anything hurts or rings afterwards.
Yes. Press Copy link: the link opens the generator on the same frequency and waveform, for example ?f=432&w=square. It never starts playing on its own; the person opening it presses Play.
No study shows that 432 Hz is healthier or more relaxing than 440 Hz. Concert pitch has been A4 = 440 Hz since 1939. You can compare the two by ear: type 432, then 440, or switch the A4 reference on the notes page.
No. Speakers work, but headphones are better for very high and very low frequencies and for checking each ear. Speakers in a room add echoes and resonances that make some frequencies louder than others.