Mono Sound Test
Find out in seconds whether your phone, headphones or speakers are playing mono or stereo. Switch deep test music between stereo, mono and the difference signal, hear exactly what changes, and run the guided mono detector to check if Mono Audio is turned on. No app and no sign-up.
- 100% free
- Stereo vs mono A/B
- Mono detector
- Live width meter
- 1Put on headphones or sit between your speakers
- 2Press play and switch between Stereo and Mono
- 3Run the Mono detector and answer two questions
Works in Chrome, Safari, Edge and Firefox on phones, tablets and computers. All sounds are generated on your device, and no microphone access is needed.
Press play to hear stereo, then switch to Mono to hear the difference.
Using one earbud or hear better in one ear? Turn on Mono Audio so you never miss half the sound. See how
What is mono sound?
Mono, short for monaural or monophonic, is audio carried on a single channel. Every speaker or earbud plays exactly the same signal, so the sound seems to come from one point in the middle. Stereo uses two channels, left and right, which carry slightly different signals so that sounds can be placed across a space between the speakers.
When stereo audio is played in mono, the two channels are added together into one. Anything that was the same on both sides stays exactly as it was. Anything that was different on each side is blended, and anything that was opposite on each side, known as out of phase, cancels itself out and can disappear completely. That is why some music sounds thinner, quieter or strangely different in mono, and why audio engineers check their mixes in mono before releasing them.
Left channel
Carries everything placed on the left, plus the shared centre.
Right channel
Carries everything placed on the right, plus the shared centre.
Mono
One combined signal, played equally from every speaker.
Difference
The parts that are different on each side, and that fade in mono.
One channel, one position
- Same sound from every speaker or earbud
- Nothing is lost if you only hear one side
- Ideal for speech, calls and single speakers
- No sense of width or direction
Two channels, a wide image
- Instruments and effects placed left to right
- Depth and space in music, films and games
- Needs two speakers or both earbuds
- Some details vanish if played in mono
How to use the mono sound test
The tool generates music and test tones in your browser, so nothing needs to be installed. Headphones give the clearest result, because each ear hears only its own channel. With speakers, sit in the middle, about the same distance from each one.
Play in Stereo
Listen to the wide mix. Hi-hats lean right, a shaker leans left and the arpeggio bounces from side to side.
Switch to Mono
Everything moves to the centre and the wide clap fades. The width meter drops towards Mono.
Try Difference
Hear only the parts that are lost when stereo is folded down to mono.
Run the detector
Answer where you heard the left-only and right-only steps to find out if your device is in mono.
What each control does
| Control | What it does | When to use it |
|---|---|---|
| Music / Test tone | A deep groove with deliberately wide stereo parts, or pink noise and pure tones | Music to hear the difference clearly, tones for technical checks |
| Stereo | Plays the original two-channel mix | Your reference for what stereo should sound like |
| Mono | Adds left and right together and sends the result to both sides | Hear exactly what a mono speaker or Mono Audio setting does |
| Difference | Plays only the left minus right signal | Find what disappears in mono |
| A/B switch | Alternates stereo and mono every 4 seconds | Compare quickly without touching anything |
| Mono detector | Plays left only, right only, then mono, and asks where you heard each step | Check whether your phone or computer is forcing mono |
| Frequency | Focuses the sound on 60 Hz to 10 kHz | Check bass and treble on a mono speaker |
| Width meter | Shows how different the two output channels are | See the change from wide to mono as you switch modes |
Protect your hearing. Keep the volume moderate, especially with in-ear headphones. Test tones can sound louder than music at the same setting.
Is my phone or computer playing mono?
Many people do not realise their device is in mono until they notice that music feels flat or that a game no longer tells them where sounds are coming from. The mono detector checks this in about 13 seconds.
In step 1 the tool sends sound only to the left channel. In step 2 it sends sound only to the right channel. Step 3 plays true mono as a reference. On a stereo system you will hear step 1 on the left and step 2 on the right. If your device is forcing mono, both steps will come from both sides and sound just like step 3. Answer the two questions under the player and the tool explains what your answers mean.
| Your answers | What it means | What to do |
|---|---|---|
| Step 1 Left, step 2 Right | Stereo is working normally | Nothing, unless you want mono for one-ear listening |
| Both steps from Both sides | Your device is playing mono | Turn off Mono Audio, or accept it if you use a single speaker or one earbud |
| Step 1 Right, step 2 Left | Left and right are swapped | Check how you wear the headphones or how the speakers are wired |
| One step was silent | One side is dead, muted or panned away | Check the cable, earbud, connection and balance setting |
| One step Both, the other one side | Channels are partly blended | Turn off sound enhancements, virtual surround or spatial audio and test again |
For the most reliable answer, use wired or Bluetooth headphones rather than a phone speaker, wear them the right way round, and close any app that might be using the microphone, since that can switch Bluetooth earbuds into a mono call mode. If you are testing speakers, sit centred between them. On a laptop or phone with built-in speakers, the left and right drivers are close together, so listen carefully or move closer. Run the detector once, change one setting at a time, then run it again so you can see exactly which setting made the difference.
For a detailed left and right check with balance and phase tools, use our left right stereo sound test.
When mono audio is the better choice
Mono is not a downgrade. In many situations it is the more practical and more accessible way to listen, which is why every major phone and computer includes a Mono Audio setting.
Hearing in one ear
If you have hearing loss in one ear, stereo can hide instruments, voices or game sounds on that side. Mono sends everything to both ears so nothing is missed.
Using one earbud
Many people wear one earbud to stay aware of their surroundings. In stereo you only hear half the mix. In mono you hear all of it in one ear.
Single speakers
Smart speakers, small Bluetooth speakers and many budget phones have one driver. They already play mono, so a mono check tells you how your music will really sound on them.
Calls and podcasts
Phone calls, voice notes and most spoken-word podcasts are recorded in mono. Speech gains nothing from stereo and is easier to follow when it is centred.
Public spaces and PA
Shops, gyms, venues and announcement systems often run in mono, because listeners stand everywhere, not between two speakers.
Checking a mix
Producers and podcasters listen in mono to make sure vocals, bass and key instruments survive on phones, laptops and smart speakers.
Why mono still matters today
Mono was the standard for recorded sound for most of the twentieth century. Stereo records only reached the mass market in the late 1950s, and through much of the 1960s many albums were released in separate mono and stereo versions, with the mono mix often treated as the main one. Radio, television and cinema sound were also mono for decades, so a huge amount of classic music and film audio was designed to be heard from a single speaker.
Today stereo and immersive formats dominate releases, yet a surprising amount of listening has quietly gone back to mono. Smart speakers in kitchens, a single Bluetooth speaker on a desk, a phone lying flat on a table, one earbud on a commute and voice calls all deliver mono or close to it. That is why a quick mono check is useful for everyone: listeners can confirm their device is doing what they expect, people with hearing differences can set up Mono Audio with confidence, and creators can make sure their work sounds right wherever it is played.
A good rule of thumb is simple. If you are listening with two ears and two speakers or both earbuds, use stereo and enjoy the space it adds. If you are listening through one speaker, one earbud or with one ear, mono makes sure nothing is missing.
How to turn Mono Audio on or off
Mono Audio is an accessibility setting on every major platform. Turn it on to hear everything in both ears, or turn it off to get stereo back. After changing it, reload this page and run the mono detector again.
Mono Audio
- Open Settings, then Accessibility.
- Tap Audio and Visual.
- Switch Mono Audio on or off.
- Check the Balance slider sits in the centre.
Mono audio
- Open Settings, then Accessibility.
- Look under Audio adjustment, Hearing enhancements or Audio and on-screen text, depending on your phone.
- Switch Mono audio on or off.
- Centre the left and right balance slider if there is one.
Mono audio
- Windows 11: open Settings, then Accessibility, then Audio.
- Windows 10: open Settings, then Ease of Access, then Audio.
- Switch Mono audio on or off.
- Turn off spatial sound or audio enhancements while testing.
Play stereo audio as mono
- Open System Settings, then Accessibility.
- Choose Audio.
- Switch Play stereo audio as mono on or off.
- Check the balance under System Settings, then Sound.
Menu names change a little between versions and phone brands. If you cannot find the option, search your settings for “mono”. Some headphone apps, car stereos and TVs also have their own mono or audio mode settings, so check those if the detector still reports mono after you switch the phone setting off.
Mono compatibility for music and podcasts
A large share of listening happens on mono devices, from smart speakers to a phone held in portrait mode. A mix that sounds great in stereo can lose its vocals, its punch or its effects when the two channels are added together. Checking mono compatibility protects your work on every device.
The problem is phase. When the same sound reaches the left and right channels with the waveform flipped, or with a small time delay, adding the channels together makes parts of it cancel. Stereo wideners, some chorus and reverb effects, out of phase microphones, and samples that use extreme width tricks are the usual causes. In stereo they sound impressively wide. In mono they shrink, sound hollow or vanish.
Centred and in phase
- Lead vocals and dialogue
- Kick drum and bass
- Snare panned to the centre
- Instruments panned left or right in phase
Wide and out of phase
- Stereo widener and spreader effects
- Out of phase layers and samples
- Very short left and right delays
- Microphones recorded with reversed polarity
You can hear this in the tool. The clap in the test music is deliberately recorded in opposite phase on each side. In Stereo it sounds wide and impressive. Switch to Mono and it almost disappears. Switch to Difference and the clap is nearly all you hear, while the kick, bass and centred parts fall away. The same thing can happen to parts of a real song, which is why engineers keep a mono button on their mixing desk.
To make a mix mono-friendly, keep the low end and the lead vocal in the centre, use width effects with care, check the correlation meter in your editing software, and listen to the whole track in mono at least once before you export it.
Which devices play in mono?
Some devices are mono by design, others switch to mono in certain situations. Knowing which is which explains many “my music sounds different” moments.
| Device | Usually | Notes |
|---|---|---|
| Smart speakers | Mono | Most single smart speakers play mono. Two identical units can often be paired as a stereo set. |
| Small Bluetooth speakers | Mono or narrow stereo | Drivers sit very close together, and many models are mono. Some offer stereo pairing. |
| Phones | Stereo or mono | Many models have stereo speakers that work best in landscape. Budget phones may have one speaker. |
| Laptops | Stereo | Real stereo, but the speakers are close together, so the image is narrow. |
| Headphones and earbuds | Stereo | Full stereo unless Mono Audio is on or the connection drops to headset mode. |
| Bluetooth headset mode | Mono | Used during calls, when the microphone is active. Sound quality drops and stereo is lost. |
| Phone calls and voice notes | Mono | Speech is transmitted on a single channel. |
| Cars and TVs | Stereo | Usually stereo, but some have mono or “voice” modes that blend channels. |
If you only hear a difference between Stereo and Mono on some of your devices, that tells you which ones are giving you real stereo. On a mono device, all four listen modes except Difference will sound almost the same.
Mono sound problems and how to fix them
| What you notice | Likely cause | How to fix it |
|---|---|---|
| Stereo and Mono sound the same | Mono Audio is on, or the device has one speaker | Turn off Mono Audio, or test with headphones |
| Music suddenly sounds flat during a call | Bluetooth switched to headset mode | End the call or close apps using the microphone, then reconnect |
| Vocals disappear and only music remains | A plug is half inserted, or one side is out of phase | Push the plug in fully and compare Stereo with Difference |
| Mono sounds much quieter than stereo | Lots of wide or out of phase content in the source | Normal for very wide mixes. Creators should reduce width effects |
| Sound only in one ear in stereo | A dead earbud, broken cable or balance setting | Check the hardware and balance, or turn on Mono Audio as a workaround |
| Detector gives a mixed result | Spatial audio, virtual surround or an equaliser app blending channels | Turn those features off and run the detector again |
Speaker sounds muffled rather than mono? Water or dust in the grille can make a phone speaker sound thin and quiet. Try our speaker water removal or speaker dust cleaner tools first.
Common mono sound myths
MythMono is just lower quality audio
Fact: Mono has the same clarity and frequency range as stereo. It only lacks the left to right placement.
MythMono means the sound comes from one side
Fact: Mono plays the same signal from every speaker, so it sits in the centre. Sound from only one side is a fault, not mono.
MythTurning on Mono Audio damages headphones
Fact: It is a software setting that changes the signal, not the hardware. You can switch it on and off as often as you like.
MythA good stereo mix always sounds fine in mono
Fact: Wide effects and phase tricks can make parts of a great stereo mix vanish in mono. It has to be checked.
Mono sound test FAQ
How do I test if my audio is mono or stereo?
Put on headphones, press Mono detector and listen. Step 1 sends sound to the left only and step 2 to the right only. If you hear both steps in both ears, your device is playing mono. If step 1 is on the left and step 2 on the right, it is playing stereo.
What is the difference between mono and stereo sound?
Mono uses one channel, so every speaker plays the same signal and the sound sits in the centre. Stereo uses two channels, left and right, so sounds can be placed across the space between the speakers.
Should I turn Mono Audio on or off?
Leave it off for the full stereo experience in music, films and games. Turn it on if you have hearing loss in one ear, use a single earbud, or often listen through one speaker, so you never miss sounds panned to one side.
Why does my music sound different in mono?
When left and right are added together, parts that were placed wide or recorded out of phase can cancel out. Use the Difference mode in the tool to hear exactly which parts are lost.
Why can I only hear sound in one earbud?
That is usually a fault, not mono. Check that both earbuds are connected and charged, that the balance slider is centred, and that the plug is fully inserted. Turning on Mono Audio is a useful workaround until you fix it.
Are smart speakers mono?
Most single smart speakers and small Bluetooth speakers play mono. Many models can be paired with an identical second speaker to create a stereo set.
Why does Bluetooth switch to mono during calls?
When the microphone is in use, many Bluetooth headphones switch to a headset profile that carries mono audio in both directions. Music returns to stereo once the call ends and the microphone is released.
What does the Difference mode do?
It plays the left channel minus the right channel. This is exactly the part of a stereo signal that is lost when it is folded down to mono, so it is a quick way to hear what a mono speaker would miss.
Does this test work on iPhone and Android?
Yes. It runs in Safari, Chrome and other modern browsers. Use headphones for the most accurate result, because phone speakers are close together and some phones have only one speaker.
How do I check if my mix is mono compatible?
Listen to your track in mono and compare it with stereo. If the vocal, bass or key instruments get noticeably quieter or hollow, look for stereo wideners, out of phase layers or very short left and right delays, and reduce them.
Is anything recorded or uploaded?
No. All sounds are generated in your browser on your own device. The tool does not use the microphone, and your settings are saved only in your browser.
Test the rest of your setup
Check left and right channels with balance and phase tools, or test every speaker in a 5.1 or 7.1 home theater with our surround sound test.
Left right stereo test →