Why music is a bad test
Stereo recordings are not balanced moment to moment. Instruments are placed across the stereo field on purpose, so a passage can be almost entirely in one channel and sound exactly like a dead speaker on the other. Older recordings do this dramatically.
A test tone removes that variable completely. The speaker test plays a single sine wave into the left channel, the right channel, or both, and nothing else. If a channel is silent during its own tone, the silence is real.
This is also why the fault often seems to come and go: it tracks the material, not the hardware.
The sequence
- Set the volume low before you start. A pure tone at high volume is unpleasant, and the 8 kHz tone especially so.
- Play the left channel alone. Then the right. Then both. Note which of the three produce sound.
- If one channel is silent, check the balance control in your operating system's sound settings for that specific output device. Balance is per device and is easy to knock without noticing.
- If you are on headphones or external speakers, push the jack fully in until it clicks. A jack seated one step short is a classic cause of one channel dropping out, and it feels connected.
- Swap the headphones or speakers for another pair. If the fault moves with them, it is the hardware; if it stays with the computer, it is the output or its settings.
- On headphones, swap left and right on your head, or reverse the cable if it is detachable. If the silence follows the earcup, it is the driver or the cable in that side.
- Try the four frequencies. A channel that plays 440 Hz and 1000 Hz but not 100 Hz is not faulty: small drivers genuinely cannot reproduce much bass.
Reading the outcome
| Left tone | Right tone | Most likely cause |
|---|---|---|
| Plays | Silent | Balance setting, a partly inserted jack, or a fault on the right side |
| Silent | Plays | The same three, mirrored |
| Silent | Silent | Not a channel problem: check the output device selection, the mute, and that the browser is allowed to play audio |
| Plays | Plays | Both channels are working. If music still sounds one-sided, the problem is the source material or an application-level balance |
| Plays quietly | Plays normally | A partly inserted jack, a damaged cable, or an operating-system balance that is off centre rather than fully over |
Compiled by MyGearCheck. Every row assumes you tested with tones rather than music, because music makes the first two rows unreliable.
The accessibility setting nobody remembers
Most operating systems have a mono audio option in their accessibility settings, which sums both channels into one and sends the same signal to both sides. It exists for good reasons and it is easy to switch on by accident.
It produces a confusing result: both channels play during a left or right test, because the system is duplicating the signal. If left and right sound identical when they should be distinct, check that setting before anything else.
Some Bluetooth headsets do something similar when they fall back to a hands-free profile, which is mono by design. If audio becomes mono the moment your microphone is in use, that is the cause and it is not a fault.
Laptop speakers specifically
Laptop speakers fail one at a time more often than people expect, and it goes unnoticed because most laptop audio is heavily processed and much of it is mono anyway.
The speaker test is the fastest way to catch it, which makes it worth running when buying second-hand. It also matters for a warranty claim, because a dated result showing one silent channel is concrete in a way that a description is not.
If one laptop speaker is dead and the machine is out of warranty, weigh the repair against a small external speaker. On many laptops the speaker is under the keyboard assembly, which makes a cheap part into an expensive job.
Frequently asked questions
Why does the left and right test matter if my music sounds fine?
Because music is mixed across the stereo field, so a dead channel can hide behind material that was mostly on the other side. A tone in one channel at a time removes that ambiguity entirely.
Is it safe to play these test tones at high volume?
No. Start low. A sustained pure tone is harder on hearing than music at the same meter reading, and the 8 kHz tone is particularly unpleasant. Raise the volume only if you hear nothing at all.
Why is there no sound at all?
Check three things in order: the output device selected in your system settings, the mute state, and whether the browser tab is allowed to play audio. Web Audio starts suspended until a user interaction, which is why the test needs a click before it can make any sound.
Can I choose which speaker or headphones the tones play through?
Not from the page. A browser plays through whatever the operating system has selected as the default output. Change the default output device in your system settings and the test follows it.
I hear 440 Hz but not 100 Hz. Is my speaker broken?
Almost certainly not. Small drivers in laptops, phones and monitors physically cannot move enough air to reproduce 100 Hz at a useful level. Judge those devices on the mid and treble tones.
My headphones work on my phone but not my laptop. What does that mean?
The headphones and cable are fine, so the fault is the laptop's output: the jack, its detection, or a setting. A combined headphone and microphone jack that has decided a headset is plugged in is a common cause.
Why did my audio go mono when I joined a call?
Bluetooth headsets switch to a hands-free profile when the microphone is in use, and that profile is mono and lower quality by design. It is a limitation of the connection, not a fault.
Can the speaker test tell which physical speaker plays a channel?
No. It sends a tone to a channel, and the operating system decides where that channel goes, including any upmixing or spatial processing on the way. On a system with those effects enabled, left and right may not land where you expect.