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Audio latency test: how far behind is your sound?
Put your microphone next to the speaker or earbud you want to test, keep the room quiet, and press Measure the delay. Six short clicks play, the microphone times each one, and you get the delay in milliseconds. Wired speakers usually show a few milliseconds, standard Bluetooth often 150 to 250, and low-latency Bluetooth about 40.
Six short clicks play through your speaker or headphones and the microphone listens for them. The samples stay in your browser and are discarded when the measurement ends; nothing is recorded or uploaded. The result is the speaker's delay plus the microphone's, so a wired setup still shows a few milliseconds.
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What the delay means
| Delay | In practice |
|---|---|
| Under 40 ms | Low. Wired speakers and headphones live here; nobody notices it on video or in a call. |
| 40 to 100 ms | Moderate. Fine for music and calls; a fast game or a live instrument may feel slightly behind. |
| 100 to 200 ms | Noticeable. Typical of Bluetooth; speech can drift from lips on video unless the app compensates. |
| Over 200 ms | High. Visible lip-sync drift and lag in games; a wired connection or a low-latency mode helps. |
What exactly is measured
The page schedules each click for an exact moment and records exactly when the microphone hears it, so the difference is the time the sound took to leave your device and come back in: the output delay (the operating system, any Bluetooth link, the speaker itself) plus the microphone's own input delay. On a wired setup that total is usually a few milliseconds; nearly all of a Bluetooth result is the Bluetooth link. The browser also reports its own estimate of the output delay, shown beside the result, which often leaves the Bluetooth buffer out.
When a delay becomes visible
For video, the broadcast standard ITU-R BT.1359 found that viewers can detect sound arriving more than about 45 ms before the picture or about 125 ms after it. Standard Bluetooth audio is often well past that 125 ms point, typically 150 to 250 ms on the basic SBC codec, while low-latency codecs such as aptX Low Latency bring it down to around 40 ms, which is why the same video can look out of sync on one pair of headphones and fine on another.
How to cut the delay
A cable removes the encoding step entirely. On Bluetooth, a low-latency codec (if both ends support it) or a game mode on the headphones shortens the delay, and many video apps already delay the picture to match the sound, so films often look fine even when games and calls do not. On a TV, the audio sync or lip sync setting adds the same delay to the picture.
How do I test Bluetooth headphone latency?
Hold one earbud or ear cup right against your phone or laptop microphone, keep the room quiet, and press Measure the delay. The microphone has to hear the clicks, so the closer the better. The result is the Bluetooth delay plus a few milliseconds from the microphone.
What is a good audio latency?
Under 40 ms feels instant. Up to about 100 ms is fine for listening and calls. Above that, video can look out of sync unless the app delays the picture to match, and games and music-making start to feel laggy.
Why is Bluetooth audio delayed?
Not because of the radio, which is close to instant, but because the audio has to be encoded on your device and decoded again in the headphones or speaker. The basic codec, SBC, often adds 150 to 250 ms that way; low-latency codecs such as aptX Low Latency do the same job in about 40.
Why does the result change between runs?
Bluetooth links adjust their buffering as conditions change, and the operating system can switch audio paths, so a few milliseconds either way is normal. A spread of more than about 20 ms between clicks in one run usually means the room was noisy.
My phone switched to the headset microphone. Does that matter?
Yes. Many phones move to the Bluetooth headset microphone when a page listens, which also switches the headphones into their call mode, with different latency from music playback. If that happens, the number describes call mode, not music. A laptop that keeps using its own microphone while it plays to the headphones gives the music-mode figure.
Sources: ITU-R BT.1359, relative timing of sound and vision; RTINGS, headphone latency; SoundStage! Solo, latency; Qualcomm, aptX Low Latency.