Left/Right Channel Test

The Audio Channel Test checks whether the left and right channels of your headphones or speakers work properly. Click a button and the browser generates a continuous test tone that comes out of the left side only, the right side only, or both together. It helps you tell whether headphones are swapped, whether one side is silent, and whether your system's left-right settings are off. Its scope is narrow: it covers the two stereo channels only. It cannot test the individual speakers of a 5.1 or 7.1 setup, cannot measure loudness or frequency response, and does not rate sound quality.

How to use it

1. Put on your headphones or switch on your speakers, and set the system volume to a low, comfortable level first, since the tone keeps playing.
2. Click 'Test Left Channel'. You should hear a steady tone from the left earpiece (or left speaker) only, with the right side completely quiet.
3. Click 'Test Right Channel'. Now only the right side should sound. Clicking another button switches directly; you do not need to stop first.
4. Click 'Test Both Channels'. Both sides should play the same sound at once.
5. When finished, click the 'Stop Playback' button that appears. The tone does not end on its own, and the audio is also shut down if you move to another tool.

What the tone is, and how to read the result

The code generates a 440 Hz sine wave, the standard A4 pitch, sets its gain to 0.2 so it is not too loud, and then uses a stereo panner to place it fully left (-1), fully right (1), or in the center (0). 'Test Both Channels' uses the center position, so both sides receive the same signal. A usage scenario: you just bought headphones and the left side seems quieter. Press 'Test Left Channel', then 'Test Right Channel'. If one side is clearly weaker, or one is silent, then once you have ruled out balance settings in software, suspect a poor plug connection or a faulty earpiece. The tone is synthesized live by the browser, so no audio file is downloaded.

Supported input and known limits

• There are three tests only: left, right, and both, always with a fixed 440 Hz single tone. You cannot change the pitch or the sound.
• It checks the two stereo channels only. Surround speakers are not supported, and it cannot measure the exact level difference between sides; you compare by ear.
• If you hear both sides during the left test, first check whether your system has a 'mono audio' accessibility option on, or whether a spatial-audio or sound-enhancement feature is mixing sound across both sides. Those settings can make the result look like a hardware fault.
• The browser sends sound to the output device your system has selected. If both speakers and headphones are connected, confirm the system output is the one you want to test.
• The tone keeps playing until you click 'Stop Playback' or another button, so do not walk away wearing headphones.
• On a phone in silent mode the system may block browser audio, so hearing nothing does not always mean a channel problem.
• It cannot tell you about Bluetooth latency or connection stability.

FAQ: There is a little sound on the right during the left test. Is that normal?

With this tool, the left test tone should be completely absent on the right. If you still hear it, common causes are system mono mixing or spatial effects, headphone leakage (also from speakers placed very close together), or a hardware defect. Try another device for comparison.

FAQ: I hear nothing at all. What should I check?

Make sure the page and the system are not muted, the system volume is above zero, and the right output device is selected. Browsers sometimes only allow audio after a user click; this tool starts only when you click a button, so that rule should not block it. If other websites are silent too, the problem is most likely with the device or system settings.

FAQ: Why 440 Hz?

It is a common standard pitch, sits in the midrange where most headphones and speakers play clearly, and makes direction easy to hear. A comment in the code gives the reason as 'clear and easy to recognize'. It does not cover the whole audio range, so this test is no substitute for a proper frequency-response measurement.

FAQ: Can it test my microphone?

No. This tool is output only and never uses the microphone. For microphones, use the site's Microphone Tester.

Privacy and processing

The test tone is synthesized entirely by your browser in real time. No audio file is downloaded, the microphone is not used, and no data is collected. When you leave the page, the code closes the audio context so it no longer holds audio resources.