How to run a left and right sound test safely
Start with your computer or phone volume low, because headphones put sound right next to your ears. Press Left, listen, then press Right. Each tone is a gentle 440 Hz beep of about a second and a half that fades in and out, so there is no sudden blast.
Lower your volume first
The test's own volume slider starts at 30% and even 100% stays well below full scale. Raise it slowly until the tone is easy to hear.
Press Left, then Right
Each tone should come only from that side. With headphones, check that the L earcup is on your left ear.
Press Both
The tone should sound centered, as if it comes from straight ahead or the middle of your head.
Use Alternate left and right
It plays left, then right, three times in a row. A steady back-and-forth makes swapped or missing sides obvious.
Wrong device playing? The tones go to whatever your computer or phone is using for sound right now. If they come out of your laptop speakers instead of your headphones, switch the output device in your sound settings and press the button again.
What your sound test result means
There are only a few possible outcomes, and each points to a different cause. A side that stays silent is usually hardware or a connection. Sides that are swapped are usually placement or wiring. A Left tone that comes from both sides almost always means a mono setting is on.
| What you hear | Likely cause | What to do |
|---|---|---|
| Left on the left, Right on the right | Everything is correct. | Nothing. |
| Only one side ever plays | A dead speaker or earbud, a damaged cable, a plug not fully inserted, balance turned all the way to one side, or a low earbud battery. | Check the balance setting below, reseat the plug, charge the earbuds, and try another device. |
| Left plays on the right | Headphones worn backward, speakers on the wrong sides of the desk, or speaker wires swapped. | Check the L and R markings, swap the speakers or their cables, and test again. |
| Left and Right both sound centered | Mono audio is turned on, or the device plays everything as one channel. | Turn off mono audio in your system settings (steps below). |
| One side is quieter | The left/right balance is off-center, or one earbud or speaker is weak or failing. | Center the balance slider, then try the same headphones on another device. |
| Nothing at all | Muted, volume at zero, or the wrong output device. | Unmute, raise the volume, and select the right output device. |
How to fix mono audio and left/right balance
Windows, macOS, and iPhone each have a mono audio switch and a left/right balance control, and both are easy to change by accident. Mono plays the same sound in both ears, which is why Left and Right sound identical. An off-center balance makes one side quieter or silent.
1. Windows 11
Mono audio: select Start, then Settings > Accessibility > Audio, and switch off the Mono audio toggle. Microsoft also shows a Mono audio toggle under Sound > Output.
Balance: go to Settings > System > Sound, select your device under Output, then open its Output settings and Volume. Make sure Left and Right are set to the same level (typically 100).
While you are in the device's Output settings, Microsoft suggests checking that the Format is a 2-channel (stereo) option, such as 2 channels, 16 bit, 48000 Hz.
2. macOS
Mono audio: choose Apple menu > System Settings > Accessibility > Audio and turn off Play stereo audio as mono.
Balance: choose Apple menu > System Settings > Sound, click Output, select your speakers or headphones, and drag the Balance slider back to the center.
3. iPhone
Open the Settings app, then go to Accessibility > Audio & Visual. Turn off Mono Audio, which otherwise makes the left and right play the same content, and drag the Balance slider to the middle.
Sources: Microsoft, Make Windows easier to hear and Fix Bluetooth audio only playing in one channel; Apple, Audio settings for accessibility on Mac, Change the sound output settings on Mac, and Adjust audio settings on iPhone.
Only one earbud or headphone side working?
If one side stays silent on every tone, first rule out settings by checking balance and mono audio above. If both look right, the cause is the device or its connection. Microsoft's checklist for Bluetooth audio playing in only one channel starts with the battery and ends with a firmware update.
- Charge both earbuds. Microsoft lists low battery as a cause of one-channel audio.
- Re-pair them. Remove the device in Bluetooth settings, put both earbuds back in the case, and pair again so both sides connect.
- Try another phone or computer. If one side is still silent there, the earbud or headphone itself is likely faulty.
- Check for firmware updates on the maker's website.
- Wired headphones: push the plug all the way in, and wiggle the cable near the plug while the tone plays. A side that cuts in and out points to a damaged cable.
For AirPods, our AirPods guide walks through Apple's exact reset steps, which re-pair both sides from scratch. Bluetooth headsets also sound much worse while their microphone is in use, because they switch into a hands-free call mode; the headset mic test explains that switch.
Why the test uses a 440 Hz tone
The tones sit at 440 Hz, a mid pitch that almost anyone can hear clearly at a low volume. A very high or very low test tone could seem silent for reasons that have nothing to do with your speakers, which would make the test misleading.
People with normal hearing perceive sound from about 20 Hz to 20,000 Hz. Age-related hearing loss usually affects the higher frequencies first before moving to lower ones, according to an evidence review on the NIH's NCBI Bookshelf. So if a high-pitched test seems to drop out, it may be your ears rather than your headphones. A mid tone avoids that confusion.
More free tests
The sound test checks what you hear. To check what other people hear and see on a call, run the mic and webcam tests too. They work the same way: in your browser, with nothing installed and nothing uploaded.
Mic test
Live meter, plain verdict, and a playback clip.
Webcam test
Camera preview, resolution, and real frame rate.
Headset mic test
Wired, USB, and Bluetooth headset checks.
Mic not working
The full checklist for a silent microphone.
Sound test questions
Where should I hear the tone when I press Left?
Only in your left ear or from your left speaker. With headphones, make sure the cup or earbud marked L is on your left side, then press Right and confirm the tone moves fully to the other side.
Will the sound test be loud?
No. Nothing plays until you press a button, the test volume starts at 30 percent, and each tone fades in and out over about a second and a half. Your system volume still applies, so turn it down before you start with headphones on.
Why do I hear the Left tone in both ears?
Mono audio is almost certainly on. It mixes both channels together so every sound plays on both sides. Turn it off in Settings, Accessibility, Audio on Windows 11, in Accessibility, Audio on a Mac, or in Accessibility, Audio and Visual on an iPhone.
How do I fix left and right audio that is swapped?
Swap what is physically reversed. Turn headphones around so the L side is on your left ear, or swap the left and right speakers or their cables. Then run Alternate left and right again to confirm the fix.
Why is one side quieter than the other?
The balance is usually off-center. Set Left and Right to the same level in your device's Output settings on Windows 11, or center the Balance slider on a Mac or iPhone. If balance is centered and one side is still quiet on another device too, the earbud or speaker itself is the problem.
Why does the sound test use a 440 Hz tone?
It is a mid pitch that nearly everyone hears clearly, even at low volume and on small speakers. High tones fade first as hearing changes with age, so a high-pitched test could seem silent even when the speaker works.
Can this test check surround sound or a center speaker?
No. It tests the two stereo channels, left and right. The Both button plays the tone equally on each side, which should sound centered, but it does not drive a separate center or rear speaker.
Does the sound test need my microphone?
No. The sound test only plays tones through your speakers or headphones, so your browser never asks for microphone access on this page. Use the mic test if you want to check your microphone.
Can I run the sound test on my phone?
Yes. Plug in or connect your headphones first, then press Left and Right. On an iPhone, the mono and balance settings are under Settings, Accessibility, Audio and Visual if the sides sound wrong.
Why can't I hear any tone at all?
Your computer is probably sending sound somewhere else or is muted. Unmute it, raise the volume, and pick the right output device in your sound settings, such as your headphones instead of a monitor. Then press a tone button again.