Online sound test
Hear the whole range your speakers or headphones can play. The sweep glides from 20 Hz to 20 kHz.
Press left, right or both to start. Space stops everything.
Sound
Phase
The sweep
Press both to start the sweep. It glides from the deepest bass to the highest treble in about twelve seconds. Listen for the point where the sound fades in at the bottom, any buzz or rattle on the way, and where it fades out at the top. You will not hear the very ends, and that is normal.
Tone and noise
Switch to tone for a steady pitch, or to noise for a general balance check: pink noise is the usual choice, brown shows the low end, blue and violet the highs. Use left and right to check each side on its own.
If something sounds wrong
A smooth wave on the scope while you hear crackling means the page sends a clean signal and the fault is further along: the driver, the cable or the speaker itself. Try another cable, port or device, and lower the volume first, because distortion at high volume is often the speaker reaching its limit.
Questions
How do I test my speakers with this page?
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.
Why do my speakers crackle or buzz?
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.
What does the oscilloscope show?
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.
What do Tone, Noise and Sweep do?
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.