Audio Latency Test

How to test audio latency

1. Choose the output to check, such as Bluetooth headphones, a soundbar or TV speakers, in your system's sound settings, and turn the volume down.
2. Press Start clicks. A short click plays every 1 second, and the circle flashes when the browser expects you to hear it.
3. Watch the circle and listen. If the click comes after the flash, move the Offset slider right; if it comes before, move it left. Fine tune moves it in 1 ms and 10 ms steps.
4. When the flash and the click seem to happen at the same moment, press Save offset.
5. Move the slider away, line it up again and save again. After a few tries, read the Average.
6. Use the Average as the starting value for the A/V sync, audio delay or lip sync setting in your player, TV or game, then fine-tune it while watching. A negative Average means the sound comes first, so delay the audio.

What is audio latency?

Audio latency is the delay between an app playing a sound and the sound reaching your ears. Wired headphones and speakers usually add little. Bluetooth usually adds more, because the sound is buffered before it plays, and soundbars, receivers and TVs can add processing time. A TV can delay the picture too, so sound may arrive before it. Either way, a large gap makes voices stop matching lips.

What a positive or negative offset means

Your offset compares when you hear the click with when the browser expected you to, judged against this screen. Sound can lag the picture or arrive before it.

Why Bluetooth audio lags behind the picture

Bluetooth headphones and speakers buffer the sound before they play it, and that takes time. How much depends on the headphones and the phone or computer they are paired with, and the page does not know which codec is in use. Bluetooth LE Audio needs fewer buffers than classic Bluetooth audio, so its delay can be shorter when both devices support it.

The latency the browser reports may leave out a Bluetooth device's own delay, and that missing part shows up as a positive offset. If one earbud is silent or quieter, check it with the Headphone Test before timing it.

How to reduce audio delay

• Use the A/V sync, audio delay or lip sync setting on your TV, soundbar, receiver or player, with your offset as the starting value.
• Turn on the TV's Game mode for games. It may shorten picture processing, which changes your offset, so test again afterwards.
• Use wired headphones or speakers when timing matters, or a low-latency mode if your Bluetooth headphones offer one in their app.
• Test again after any change: an offset belongs to one output and one screen.

What this test can detect

• How much later or earlier the sound reaches you than the browser expects, as an offset in milliseconds that you set by eye and ear.
• Delay the browser does not account for, which can come from Bluetooth headphones and speakers, soundbars and receivers.
• Sound that arrives before the picture because the screen is slower, as with a TV processing the picture, which shows as a negative offset.
• The output latency and base latency your browser reports, or Not reported where it gives 0 or no value.
• How outputs compare: the Estimated total for wired headphones, built-in speakers and Bluetooth, tested one after another.

How it works

The page loops a 1-second Web Audio buffer, so a 12 ms click at 2 kHz sounds every 1 second on the audio clock. Each frame it reads getOutputTimestamp(), which pairs the audio and page clocks, and lights the circle for 100 ms from when the browser expects the click to leave your output, moved by your Offset (−200 to +500 ms).

Output latency and Base latency are the browser's outputLatency and baseLatency, shown as Not reported when missing or 0. Estimated total adds your offset to Output latency. Nothing is recorded.