When you run the Sound Latency Test on SoundLatencyTest.com, your microphone audio is captured locally in your browser, used to calculate a round-trip latency figure in milliseconds, and then discarded. It is never recorded. It is never stored. It is never transmitted to any server. Nothing you say, sing, play, or produce near your microphone during this test leaves your device.
This page documents exactly how that works — step by step — so you do not have to take it on trust.
How the Microphone Pipeline Works
The Sound Latency Test uses your microphone as a measurement instrument, not a recording device. The pipeline has five stages, all of which occur entirely within your browser:
Stage 1 — Permission prompt The browser displays a permission prompt before the microphone is accessed. This is a browser-enforced security requirement. The site cannot access your microphone without your explicit approval. If you decline, the test does not run and no audio of any kind is accessed.
Stage 2 — Local audio stream Once permission is granted, the browser opens a live MediaStream from your microphone using the getUserMedia() API. This stream exists only in your browser’s memory. It is not routed to any external server, not logged by any analytics tool, and not stored in any browser cache or persistent storage.
Stage 3 — Web Audio API processing The microphone stream is connected to a MediaStreamAudioSourceNode within the browser’s AudioContext. This keeps all audio processing inside the Web Audio API’s local processing graph. The captured audio frames are held in a short in-memory buffer — covering approximately 500 ms — for the duration of the cross-correlation analysis. No audio data leaves this local processing graph at any point.
Stage 4 — Cross-correlation and result calculation The in-memory audio buffer is compared against the reference tone burst waveform using cross-correlation to identify the round-trip latency. This calculation produces a single number: the delay in milliseconds. That number is what the tool displays. The audio buffer that produced it is not retained.
Stage 5 — Session clear When the test completes — or when you close or reload the tab — the MediaStream is closed, the AudioContext is suspended, and all in-memory audio buffers are released. There is no persistent copy of your microphone audio anywhere on your device or on any server after this point.
What This Site Never Does With Your Audio
- Never records your microphone audio to any file or storage medium
- Never transmits microphone audio over the internet to any server, including this site’s own server
- Never shares microphone audio with Google Analytics, advertising networks, or any third-party service
- Never stores microphone audio in browser localStorage, sessionStorage, IndexedDB, or cookies
- Never retains microphone audio after the test session ends
- Never uses microphone audio for any purpose other than calculating the round-trip latency figure displayed on screen
- Never accesses the microphone without displaying the browser’s permission prompt first
Advertising and Analytics Are Separate From Your Audio
SoundLatencyTest.com does not currently run advertising. If analytics tools are present on this site, they operate entirely separately from the Web Audio API pipeline. Analytics tools collect anonymous page-level data — page views, browser type, approximate region — through standard HTTP request metadata. They have no access to the Web Audio API, no access to the MediaStream, and no ability to interact with microphone audio in any form.
The microphone permission you grant to this site is scoped to the Web Audio API measurement pipeline only. It does not extend to any other script or service running on the page.
File Uploads
The Sound Latency Test does not involve file uploads of any kind. No audio files are uploaded to any server as part of using this site. The only audio data involved in the test is the live microphone stream processed locally as described above.
HTTPS Encryption
All pages on SoundLatencyTest.com are served over HTTPS. This means all data exchanged between your browser and this site’s server — page content, scripts, and any voluntary form submissions such as contact messages — is encrypted in transit. HTTPS does not apply to the microphone audio pipeline, because that audio never travels over the network in the first place.
Cookies and Tool Data
The latency result calculated during your test session is displayed on screen for your reference. It is not written to a cookie, not stored in localStorage, and not sent to any server. Closing or reloading the page clears the result entirely. For a full explanation of what cookies this site uses and why, see the Cookie Policy.
Children’s Privacy
SoundLatencyTest.com does not knowingly collect personal data from children under the age of 13. The Sound Latency Test does not require account registration, does not request personal information, and does not retain audio data from any user. If you believe a child has submitted personal data through the contact form on this site, contact Jackson Cooper at contact@soundlatencytest.com and the data will be deleted promptly.
Reporting a Security Concern
If you identify a potential security vulnerability on SoundLatencyTest.com — including any behaviour that suggests microphone audio or user data is being handled contrary to what is documented on this page — please report it immediately via the Contact page with the subject line “Security Concern.” Jackson Cooper reviews all security reports personally within 48 hours.
Responsible disclosure is welcomed. Details of any verified vulnerability will not be published until a fix is in place.
Your Privacy Rights
Your rights regarding any personal data this site may hold — including the right to access, correct, or request deletion — are documented in full on the Privacy Policy and GDPR and CCPA pages.
Questions About Data Handling
For any question about how SoundLatencyTest.com handles data that is not answered on this page, use the Contact page or email contact@soundlatencytest.com directly. Privacy and data requests receive a response within 7 business days.
Written by Jackson Cooper, founder of SoundLatencyTest.com. Last updated: June 2026.