This frequency sweep plays a sine tone that glides smoothly from one frequency to another, normally from 20 Hz to 20 kHz, the range of human hearing. As it plays, the display shows the frequency you are hearing, and the Mark button records the exact point where the sound fades out, comes back, booms, buzzes or rattles. Use it as a frequency sweep test for speakers, headphones, subwoofers and car audio, or to check how high you can hear. It runs in any current browser on Windows, Mac, iPhone and Android, and works through wired, USB and Bluetooth audio.
How to run a frequency sweep
- Set your system volume low, about a quarter, before the first run.
- Pick a range: Full range for a whole speaker, Bass or Subwoofer for low end checks, High end for treble and hearing. You can also type any start and end frequency.
- Press Play sweep and raise the volume until the middle of the sweep is comfortable.
- Press Mark or the M key whenever you hear a change: the bass appearing, the treble vanishing, a buzz or a drop.
- If something rattles, press Hold tone. The sweep stops on that frequency so you can find the source, then Resume carries on.
- Press Play next to any mark to hear that frequency again as a steady tone, and Copy results to save the list.
Marks are corrected for the output delay your browser reports, but your reaction time still makes them a little late. Sweep the same edge both ways with Up and down: the tester shows the point halfway between your up and down marks, where the two delays cancel out.
Log or linear, up or down
A log sweep spends the same time on every octave, so 20 to 40 Hz gets as long as 10 to 20 kHz. That matches how we hear pitch and is the right choice for most tests. A linear sweep moves the same number of hertz every second. From 20 Hz to 20 kHz it rushes through the bass in a fraction of a second and spends half its time above 10 kHz, which makes it useful for the treble and for hearing checks, and poor for anything else.
| Sweep | Rate | Time in the bass, 20 to 200 Hz |
|---|---|---|
| 20 Hz to 20 kHz, log, 20 s | 0.50 octaves per second | 6.7 s |
| 20 Hz to 20 kHz, linear, 20 s | 999 Hz per second | 0.18 s |
| 8 kHz to 20 kHz, linear, 30 s | 400 Hz per second | none |
What the results mean
| Readout | What it tells you | Typical result |
|---|---|---|
| Frequency now | The tone reaching your ears, corrected for output delay | Follows the sweep smoothly |
| Lowest mark | Where the bass became audible on an upward sweep | Phones 300 to 500 Hz, laptops 150 to 200 Hz, bookshelf speakers 50 to 60 Hz, subwoofers 20 to 35 Hz |
| Highest mark | Where the treble vanished | 16 to 18 kHz for young adults, 12 to 15 kHz for many people over 40 |
| Sweep rate | How fast the tone moves | 0.5 octaves per second for a 20 second full range sweep |
| Marks | How many points you recorded, up and down | One for each change you heard |
A speaker that starts higher than these figures may simply be small. One that starts much higher than it used to, or sounds thin on music, may have a torn surround or a blown woofer.
Something buzzes or rattles at one frequency
A rattle that comes and goes as the tone passes a certain frequency is a resonance. Press Hold tone on it, then touch things one at a time: the speaker grille, the cabinet, a shelf, a picture frame, a car door panel. When the buzz stops under your hand, you have found it.
- Loose grille, trim or screws. Tighten screws, add felt pads, or refit the grille.
- Objects on or near the speaker. Move them; even a pen on a desk can buzz at 60 Hz.
- Inside the speaker. If the buzz stays when everything nearby is still, and it appears at the same frequency at low volume, the cone, surround or voice coil may be damaged. Mark the frequency and copy the results for a warranty claim.
The sound drops out and comes back
In the bass, a tone that almost disappears at one frequency and returns a few hertz later is usually the room, not the speaker. Sound bouncing off walls cancels itself at certain spots. Move your head a metre and repeat: if the dip moves, it is the room. If both speakers sound thin together but fine apart, one may be wired the wrong way round; swap the plus and minus wires on one speaker and run the sweep again. A dip that stays put in every seat and on every channel points to the speaker itself.
One side is quieter or missing
Switch Output to Left, then Right, and run the sweep on each. Small level differences are normal, but a channel that loses all treble or all bass has a faulty driver, cable or connector. Check the balance setting in your sound settings, then use the left right audio test to confirm which side fails. For headphones, see headphones not working.
Checking your hearing range
Choose High end (8 kHz to 20 kHz, linear), set a quiet but clear level at 8 kHz, and mark the moment the tone fades. Run it Up and down to cancel your reaction time. The result is a rough guide only: it depends on your headphones and their treble. The hearing frequency test checks each ear in steps, and a hearing professional can test you properly.
Testing bass and subwoofers
Use Subwoofer (15 to 150 Hz) and sweep Down: the point where the rumble fades is the lowest note your system plays. Then sweep Up and mark where the subwoofer hands over to the main speakers, normally around 80 Hz. A loud bump near the handover means the subwoofer level or crossover is set too high. Ready made test tones are on the subwoofer test tones page, and single notes are on the bass test.
Why a frequency sweep here cannot draw a response graph
The tester knows the exact frequency it sends, but not the sound level in the room, so it cannot draw a frequency response graph. Doing that needs a measurement microphone and room measurement software. Your marks also include your reaction time and your hearing, so treat them as a careful listening test, not a lab measurement. Bluetooth adds compression and usually a delay of 100 to 300 ms; the readout allows for the delay your browser reports, but the most accurate marks come from wired headphones or speakers. To play one frequency for as long as you like, use the tone generator.
Frequency sweep questions
What is a frequency sweep used for?
A sweep plays every frequency in a range, one after another, so you can hear where a speaker or headphone starts, where it stops, and where it buzzes, booms or drops out. It is also a quick way to find your own upper hearing limit.
How long should a frequency sweep be?
For a quick check of a speaker from 20 Hz to 20 kHz, 20 to 30 seconds works well. Slow it to 60 seconds or more when you are hunting for a rattle, so each frequency lasts long enough for the buzz to build up.
Can I sweep backwards, from high to low?
Yes. Choose Down to start at the top, or Up and down to go both ways without a gap. Sweeping down is the better way to find where bass starts on a subwoofer, and sweeping both ways lets you cancel your reaction time when you mark an edge.
Why do some frequencies sound louder than others?
Three reasons. Your ears are most sensitive between about 2 and 5 kHz, so those tones seem loud at the same level. Every speaker has peaks and dips in its response. And in a room, bass notes build up in some places and cancel in others, so moving your head changes them.
Is a frequency sweep safe for my speakers?
Yes at a normal listening level. Do not turn the volume up to hear the very lowest or highest tones: below its range a woofer moves too far and buzzes, and a long loud sweep at the top can heat a tweeter.
Can I download the sweep as an audio file?
Press Download WAV under the marks. You get one pass of the sweep with your range, scale, direction, output and volume, as a 16 bit, 44.1 kHz WAV file made in your browser.