Speaker test

Left, right, a 20 Hz to 20 kHz sweep and a polarity check. Every tone is generated in your browser.

Turn your volume down before starting

These tests generate pure tones, which sound louder than music at the same level. With headphones on, start quiet and raise it gradually.

Silent

Volume 25% Balance L R ·

Channels

Check each channel comes out where it should. If "left" plays on the right, your cables or connector are crossed.

Frequency sweep

0 Hz

Elapsed: 0.0 / 22 s

201005002k8k20k

Runs from bass to treble. Note where you start hearing it and where you stop: that is the real range of your speakers, and of your ears.

A young adult reaches about 17-18 kHz; at fifty, around 12 kHz. If you stop hearing it sooner it may be the speaker or it may be your age — to separate the two, try different headphones.

Fixed tone

Holds one frequency. Useful for finding furniture or room resonances: if something rattles at a particular frequency, that is the room, not the speaker.

Polarity

Two identical tones, one inverted. In phase the sound comes from the centre and feels full; out of phase it sounds diffuse and loses bass. If you hear no difference, one speaker is wired backwards.

Generated right here, in your browser. What you type never leaves your device.

Keep going with Audio test Fix my speaker Microphone test Audio latency test

This test generates tones in your own browser with the Web Audio API. It plays no file: it synthesises pure sine waves, which is exactly what you want for judging a speaker without the test material adding colour of its own.

Start with the basics — that each channel plays where it should — then move to what almost nobody checks: how far your speakers actually reach at both ends of the spectrum, and whether one is wired with reversed polarity, a silent fault that steals your bass without anything sounding obviously wrong.

One warning first: a pure tone is perceived as louder than music at the same level, and it gives no warning. With headphones on, start quiet and raise it gradually.

Manual

How to use it

1
Turn the volume down first

Pure tones concentrate all their energy at one frequency, so they sound louder than you expect and at certain pitches are genuinely unpleasant. Start at minimum and work up.
2
Check the channels separately

Press left, then right. It must play where it says. If they are crossed, the fault is the cable, the connector or the system configuration — not the speakers.
3
Run the sweep

It runs 20 Hz to 20 kHz over twenty-two seconds. Watch for two moments: when you first hear something at the bottom, and when it disappears at the top. Between those points is the real range of your equipment and your ears together.
4
Hunt resonances with the fixed tone

If something buzzed or rattled during the sweep, go back to that frequency with the fixed tone and hold it. It is nearly always furniture, a window, or the speaker cabinet — not a fault in the driver.
5
Test the polarity

Listen to "in phase" then "out of phase" with the speakers equidistant. The difference should be obvious: in phase the sound sits in the centre and has body, out of phase it falls apart and loses bass.

In depth

Things worth keeping in mind

What the sweep tells you

A speaker does not reproduce every frequency equally. It has a limit at the bottom set by cone size and cabinet volume, and one at the top set by the tweeter. In between, the response is not flat either: it rises and dips.

The sweep does not give you a measured curve — that needs a calibrated microphone — but it does give you the extremes, which is what you notice most. Laptop speakers usually start producing sound around 150-200 Hz; decent bookshelf speakers reach 50-60 Hz; a subwoofer gets to 30 or below.

Hearing nothing below 100 Hz means no real bass: these are small drivers
An abrupt cut at the top before 15 kHz may be the speaker or may be your age
A buzz or rattle at one specific frequency is resonance, not distortion

Reversed polarity: the fault that does not sound like one

If a speaker has its wires swapped, its cone moves inward while the other moves outward. The two waves partially cancel where you are listening, and the first thing to go is the bass, because its wavelength is long and the cancellation is more complete.

What makes it treacherous is that it does not sound broken. It sounds weak, diffuse, with no centre. Plenty of people live with it for years and blame the speakers. The phase test reveals it in two seconds: if "in phase" and "out of phase" sound much the same to you, something in your chain is already reversed.

Headphones versus speakers

With headphones each ear gets only its own channel, so the channel test is unambiguous and the phase test feels different: out of phase the sound seems to come from inside your head and goes diffuse, rather than losing bass.

With speakers the room joins in. Walls reflect, and certain frequencies reinforce or cancel depending on where you sit. If the sweep has an odd hole in it, try moving half a metre: if the hole moves with you, it is the room, not the equipment.

Headphones: isolate the channel, ideal for checking wiring
Speakers: the room matters as much as the equipment
The same speaker sounds different in two rooms, and neither is broken

How far hearing actually reaches

The range everyone quotes, 20 Hz to 20 kHz, describes a young adult under ideal conditions. Reality narrows with age, and always from the top: by thirty many people no longer pass 16 kHz, and by fifty it is around 12.

So it is worth not confusing the two things the sweep measures at once. If you stop hearing at 14 kHz, that may be the tweeter or it may be your ears. To separate them, repeat with different headphones: if the limit moves, it was the equipment; if it does not, it is you.

History

From a paper cone to the speaker in your pocket

The moving-coil speaker used by nearly every device in your home was patented by Chester Rice and Edward Kellogg at General Electric in 1925. They did not invent the principle, which was already known, but the specific combination — light coil, strong magnet, paper cone on a suspension — that made it sound good and cost little to build. A century later the scheme is unchanged.

Before that, gramophones were purely mechanical: the needle moved a diaphragm and a conical horn amplified the sound acoustically, with no electricity at all. They were surprisingly loud, but the range was very narrow and volume could not be controlled.

The modern sealed cabinet was formalised by Edgar Villchur in 1954 with his acoustic suspension design, which uses the air trapped inside the box as a spring. It allowed bass from small enclosures, and that is why a bookshelf speaker can do what once required furniture.

Two-channel stereo, the thing you are checking here, was patented by Alan Blumlein at EMI in 1931. It took twenty-five years to reach consumers, and it remains the dominant format despite every attempt to replace it with more channels.

1925: Moving-coil speaker
1931: Stereo patented
20 Hz-20 kHz: Nominal hearing range
~12 kHz: Typical limit at fifty

How it works

From a number to a wave of pressure

Your browser plays no file here. An oscillator generates the wave by computing the next sample each time the sound card asks for one: for a sine, that is literally evaluating the sine function at the requested frequency, 48,000 times a second.

That stream of numbers goes to the digital-to-analogue converter, which turns it into a varying voltage. The amplifier raises it and feeds the speaker’s voice coil, which sits inside a fixed magnet. The changing current pushes and pulls the coil, the coil drags the cone, and the cone pushes air. That is all sound is: air pushed in rhythm.

This sweep is exponential rather than linear, and that decision matters. Hearing perceives pitch logarithmically: the distance you hear between 100 and 200 Hz is the same as between 1,000 and 2,000, even though in hertz it is ten times larger. A linear sweep would spend nineteen of its twenty seconds in the treble and cross the entire bass in a blink.

The polarity test multiplies one channel by minus one. That inverts the wave: where there was a crest there is now a trough. Summed in the air, the two waves partially cancel, and the cancellation is more complete the lower the tone, because its wavelength is long compared with the spacing between the two speakers: the two inverted waves reach you almost perfectly opposed.

And everything fades out on a ramp, never abruptly. Cutting a wave mid-cycle produces an instantaneous jump in pressure — a click — which through a subwoofer can be louder than the tone itself and, at worst, mistreats the driver.

By hand

Checking polarity with a battery

If the phase test says something is reversed but you do not know which, there is a classic method needing no instruments. It works only on passive speakers, the kind connected with bare wire.

1

Never do this with the system powered. Release both wires from the speaker you want to check.
2

Positive wire to the positive terminal, for an instant only. Do not leave it connected.
3

If it pushes outward, that wire’s polarity matches the battery. If it sucks inward, it is reversed.
4

Same battery and wire orientation. Both cones should move the same way; if one pushes out and the other pulls in, that is the reversed one.
5

Once the wiring is corrected, replay "in phase" and "out of phase". The difference should now be obvious.

Diagnosis

If something is not working

Symptom:Nothing plays at all

Likely cause:: Almost always the selected output device rather than the speaker: the system is sending sound somewhere else.
What to do:: Check the system output selector points at the right device. Then volume, including the speaker’s own if it has one, and the browser mute — every tab can be muted separately.

Symptom:Only one channel plays

Likely cause:: A half-inserted cable, a dirty connector, or system balance pushed to one side.
What to do:: Push the connector fully home: a half-seated jack typically gives one channel. Check balance in sound settings. If it is a cable, wiggle it near the connector while a tone plays: if it cuts in and out, the cable has broken there.

Symptom:The channels are swapped

Likely cause:: Cables interchanged at the amplifier, or a reversed channel configuration in the system.
What to do:: Start with the physical: swap the two cables at the amplifier and retest. If they are still crossed, it is system or application configuration.

Symptom:Almost no bass even at high volume

Likely cause:: Either reversed polarity on one speaker, or simply small drivers that do not go below 150 Hz.
What to do:: Run the phase test. If "in phase" and "out of phase" sound the same, something is reversed and the wiring needs checking. If the difference is clear, your speakers simply do not reach that low — and the sweep confirms it.

Symptom:Something rattles at a particular frequency

Likely cause:: Resonance. Furniture, a window pane, or the cabinet itself vibrates sympathetically at that frequency.
What to do:: Hold the fixed tone at that frequency and touch objects until the noise stops — that locates it. Isolating the speaker from the surface with something soft usually solves it. If the rattle comes from the cone itself, the driver is damaged.

Symptom:A constant hiss even with nothing playing

Likely cause:: Amplifier noise floor or mains interference, not the speakers.
What to do:: Turn the amplifier down and the source up: if the hiss drops, gain was badly distributed. Try a different socket and keep audio cables away from power cables.

Trivia

Things worth knowing

Bass has no direction

Below about 80 Hz the ear stops localising where a sound came from: at those frequencies the wave bends around your head leaving no level difference between one ear and the other, which is the main cue we use to place a sound. That is why a subwoofer system uses only one, and why you can put it wherever it fits.

Equal-loudness curves explain the old "loudness" button

The ear is less sensitive to bass at low volume. Older equipment carried a button that boosted it precisely when you were listening quietly, to compensate for that curve.

A speaker is also a microphone

The mechanism is reversible: push the cone and the coil generates current. Old intercoms used the same speaker to talk and to listen, switching the circuit between the two.

The gramophone horn was not decoration

It was the amplifier. A conical horn matches the impedance between diaphragm and air, multiplying efficiency with no electricity. The same principle is still used in public address speakers.

Stereo was invented for cinema

Blumlein patented it in 1931 after being irritated that in talking pictures the voice always came from the centre of the screen, even when the actor stood to one side.

Questions

Frequently asked questions

Can this damage my speakers?

Not at sensible volume. Pure tones ask more of a driver than music does because all the energy sits at one frequency, so do not hold them loud for minutes, especially in the treble. Fades are ramped to avoid clicks, which are what actually mistreats a speaker.

I hear nothing above 15 kHz — are they broken?

Probably not. The upper limit of hearing falls with age: by thirty many people do not pass 16 kHz, and by fifty it is around 12. To separate equipment from ears, repeat with different headphones; if the limit moves, it was the equipment.

Does it work with Bluetooth headphones?

Yes, though bear in mind the wireless codec compresses the audio and may clip the extremes, particularly the treble. To judge the real range of a pair of headphones, test them wired if you can.

What does out of phase actually mean?

That a speaker’s wires are reversed, so its cone moves inward while the other moves outward. The waves partially cancel where you listen and the bass disappears. It does not sound broken, it sounds weak and centreless, which is what makes it hard to spot.

Why does the sweep not move at a constant speed?

Because it advances exponentially, following how the ear perceives pitch. A linear sweep would cross the entire bass in under a second and spend the rest of the time in the treble, which is the opposite of what is useful.

Does this page send anything to a server?

No. Tones are generated in your browser with the Web Audio API; no audio is downloaded or uploaded. Closing the tab leaves nothing behind.