Speaker test

Turn the volume down low, then press Left. You should hear a steady tone from the left speaker only, and the left half of the scope should move while the right half stays flat. Do the same with Right, then Both.

The tone is a plain sine wave, so a buzz, a rattle or a missing side points to the speaker, the cable or a setting. The keys A, S and D start Left, Both and Right, and Space stops everything.

Play the other channel on the same page. If Left works and Right does not, follow the signal on that side: first the balance slider in your system sound settings, then the cable and the port, then another device.

If the same side stays silent on every device, the speaker or the headphone itself is the likely cause.

Press Left. If the sound comes from the right side, the channels are reversed. Check the output settings of your system or audio interface, and how the speaker cables are connected.

With headphones, check that you are wearing them the right way round: the small L and R marks are easy to miss.

Play Both and listen from the middle between the speakers. If one side is clearly quieter, check the balance slider in your system and in the app you use, then the cable.

Then swap the two speakers' places. If the quiet sound moves with the speaker, that speaker is weaker. If it stays on the same side of the room, the cause is the room or the setup, for example a speaker pushed into a corner.

Lower the volume first: distortion at high volume is often the speaker reaching its limit. If it also crackles at low volume, try another cable, port or device, and keep the speakers away from power adapters and phones, which can add interference. Bluetooth speakers can crackle when the connection is weak or far away.

The scope helps to tell where the problem is. If the wave on the scope is smooth while you hear crackling, the page is sending a clean signal and the fault is further along: the system driver, the cable or the speaker.

It draws the signal the page is sending to your audio output right now: the left channel on the left, the right channel on the right, and the volume as height. A smooth wave means the signal is clean. A flat line on one side means nothing is being sent to that channel.

If the wave moves but you hear nothing, look at the system volume, the cable, the speaker or the selected output device. It shows what the browser sends, not what comes out of the speaker.

Tone is a pure sine wave at the frequency you choose, handy for finding a part that rattles at one pitch. Noise is a steady hiss in five colours. Sweep glides from 20 Hz to 20 kHz in about twelve seconds, so you can hear where a speaker starts to fade, rattle or distort.

White noise has the same energy at every frequency step, so it sounds bright and hissy, like static. Pink noise has the same energy in every octave, which sounds more natural, a bit like steady rain, and it is the usual choice for checking whether both speakers sound equally full. Brown noise has more low frequencies and sounds like a rumble. Blue and violet have more high frequencies and sound thin and sharp.

If you are unsure, start with pink.

Both your hearing and your speakers have limits. Many people hear from about 20 Hz to 20 kHz when they are young, and the top end fades with age. Small laptop and phone speakers often play very little below roughly 100 Hz.

This page also cuts tones under 35 Hz on purpose, because they only make small speakers move without making sound. A sweep that seems to start late or end early is therefore normal.

The page starts at a low volume, limits its maximum level, fades sounds in and out and filters out the deepest bass, which all helps. It cannot make a damaged or very small speaker safe, though.

Keep the volume moderate, avoid long loud tones in the lowest and highest ranges, and stop at the first sign of distortion: Space stops everything at once. Loud sound can also harm your hearing. You use the page at your own risk.

Yes, in current browsers. Tap a button to start, because browsers only allow sound after a tap. If you hear nothing on an iPhone, check that the silent switch is off and the volume is up.

Many phone speakers are mono or only weakly stereo, so a left and right test makes more sense with headphones.

Yes. Press Left and check which ear plays; it should match the L mark on the headphones. Then check Right and Both. Keep the volume low.

Bluetooth earbuds can need a moment to wake up, so the first fraction of a second may be missed. Press the button again if you hear nothing.

No. The sounds are generated in your browser. Nothing is recorded, the page does not use your microphone, and no audio is sent anywhere.

It is good enough to find a dead channel, swapped sides, a rattle or obvious distortion. It is not a measurement. Your system may apply sound enhancements, the speaker and the room shape what you hear, and without a calibrated microphone there are no real numbers. For acoustic measurements you need proper equipment.

No. The test runs in your browser, so there is nothing to install and no account to create.

Two speakers are in phase when their cones move the same way at the same time. Wired out of phase, one pushes while the other pulls: the bass thins out and the sound seems to come from nowhere in particular.

Choose Both and Noise (pink is the usual choice), sit in the middle between the speakers and flip the Phase switch (key P). Orange is In phase, grey is Out of phase, which inverts the right speaker. In phase should sound solid and centred between the speakers, out of phase thinner and vague, especially in the bass. If the out-of-phase version sounds better, one speaker's plus and minus wires are probably reversed.

The test compares your two speakers with each other; it cannot tell you which wire is the positive one.

Press 40 Hz and then 100 Hz at a moderate volume. A working subwoofer should clearly play both. If you hear nothing at 40 Hz, check the power, the cable, the level knob and the crossover setting. If something rattles at one of the two tones, you have found a loose part or a resonance.

Tones under 35 Hz are cut on this page on purpose, so 40 Hz is the lowest check it offers.