How to generate a test tone
- Turn your device volume down. Choose Sine for one frequency, Square for a tone with harmonics, or Sweep for a moving sine tone.
- Set a frequency from 20 to 20,000 Hz with the field, the slider, the step keys or a preset. For a sweep, set a start and end frequency or pick a range.
- Press Play tone or Play sweep. While a steady tone plays, you can change its frequency, waveform or output channel. Press Stop or Escape to end it; it also stops at the time you set or when you leave the tab.
It works as a frequency generator and a sine wave generator in one. The readout shows the frequency the oscillator is playing and the nearest note at A4 = 440 Hz, so 440 Hz reads A4 and 445 Hz reads A4 +20 cents. The step keys move one hertz or one octave, and the Space bar plays and stops when you are not typing in a field.
Test tones for speakers
Use a sine wave when you want to hear one frequency. The presets cover 40 and 60 Hz for low bass, 100 Hz for bass, 440 Hz for the A4 tuning note, 1,000 Hz for the midrange and 10,000 Hz for treble. These frequencies will not sound equally loud. Compare left and right at the same setting, with your playback device set to stereo.
A square wave is useful for hearing the difference harmonics make. A 40 Hz square wave includes energy above 40 Hz, so hearing it on a small speaker does not prove that speaker can reproduce a 40 Hz sine. The sub bass guide explains how fundamentals and harmonics contribute to low notes.
Find a ringing frequency by ear
A tone can put a number on a sound you can hear but not place. If a snare or a vocal rings on one pitch, play a sine tone quietly beside the track and move the frequency until the two pitches line up. Then cut a narrow bell at that frequency in Bevel EQ and listen for the ring to drop. The guide to reading a spectrum analyzer shows how to confirm the same peak on a graph before you cut it.
A slow sweep through your monitors does the same for the room. A note that booms or almost vanishes as the sweep passes it comes from the room or the speakers, not the mix, so move the speakers or your listening position before you EQ a track to suit it.
How the frequency sweep works
The sweep follows an exponential frequency curve, also called a logarithmic sweep: each octave takes the same time. A sweep from 20 to 20,000 Hz reaches about 632 Hz halfway through, the geometric mean of its endpoints. Put the higher frequency first for a downward sweep. Full range plays 20 Hz to 20 kHz, Low end 20 to 250 Hz and Top end 8 to 20 kHz.
The Web Audio API schedules the frequency ramp and stop on its audio clock. Short fades soften the start and end. A sweep helps you listen for changes or rattles; measuring frequency response also needs a measurement microphone and analysis of the recorded output.
Levels and hearing safety
Every visit starts at −30 dBFS of digital level, and the level fader stops at −12 dBFS; your device volume and amplifier still decide the level at your ears. Each tone fades in over 20 milliseconds, so it never starts with a jump, and it stops by itself after at most 30 seconds.
At the same setting, a square wave measures louder than a sine, because its harmonics add energy. The generator trims the square by the difference, measured with the same K-weighting as our loudness meter: about 2.3 dB at 1 kHz and 3.3 dB at 40 Hz. Switching between sine and square therefore never jumps up in level.
Keep tests quiet and brief. If a speaker rattles or the tone is uncomfortable, stop. A missing tone is not a reason to keep turning up the volume. Read the guide to the human hearing range for why level changes across the frequency range and why a browser tone is not a calibrated hearing test.
Questions
How do I generate a test tone online?
Choose Sine, enter a frequency in hertz and press Play tone. The 440 Hz preset plays A4; 1,000 Hz is a midrange test tone. The tone starts at −30 dBFS and stops by itself after the time you set, up to 30 seconds. Start with your device volume low.
What is the difference between a sine wave and a square wave?
A sine wave contains one frequency. A square wave also contains odd harmonics at three, five, seven and further odd multiples of its fundamental, so it sounds brighter and buzzier. At the same setting a square measures louder than a sine, so this generator plays it a little lower and the two measure the same loudness.
How do I test my speakers with a frequency sweep?
Choose Sweep, pick a range such as Full range or Low end, and press Play sweep. It plays a sine wave that moves through the range with equal time per octave. Switch between Left, Both and Right while it plays to compare stereo speakers. A sweep can reveal changes in level or rattles, but it does not measure a speaker's frequency response.
Can a tone generator damage my hearing or speakers?
Loud tones can. A steady tone at a high volume can hurt your hearing, and a loud low or high tone can damage a small speaker or tweeter. This generator starts at −30 dBFS, stops its level fader at −12 dBFS and stops itself after 30 seconds at most, but your device volume still decides how loud it is. Start low and turn up slowly.
Why can I not hear a low or high test tone?
Your speakers, headphones, output settings and hearing all affect what you hear. Small speakers often cannot reproduce deep bass. Do not raise the volume to chase an inaudible tone. This generator is not a calibrated hearing test.
Is this tone generator free, and does it upload anything?
It is free with no sign-up. The Web Audio API creates the sound inside your browser. No microphone, audio file or upload is needed, and playback works offline after the page loads.
Link to this generator
Share a test tone tool in a lesson or an article with this plain HTML link.
<a href="https://vitricaudio.com/tools/tone-generator">Free online tone generator</a> by Vitric Audio