Your practice log, your settings and the voices you prepare for offline use are kept in your browser's storage on this device, and nowhere else: we never see them. A backup (Settings → Data) is a file you download, holding your log and settings but no audio. Clearing this site's data in your browser removes all of it, and there is no copy anywhere to restore it from, so keep a backup if your log matters to you.
Repeat-back listens to you through your microphone, only while you record. The recording is analysed on your device to compare your pitch with the voice's, and then discarded. It is never uploaded, never kept on the device, and never part of a backup.
Like any website, our server keeps standard access logs: your IP address, your browser's type, the pages and files requested (with any ?from= tag a link carried), the time, and the site that linked you. We keep them for security and to count how many people use the tone lab, on how many days, from which countries, and which links and sites brought them. They are kept for 15 days and not combined with anything else. The daily counts we make from them keep no addresses and nothing else about you.
While the tone lab is open on your screen, the page asks the server which version is live: about every half hour, when you come back to it, and when your connection comes back. Each ask is an ordinary request like the others, logged the same way; it sends nothing of yours, and it isn't counted as a visit.
The practice audio is Microsoft Azure neural voices, synthesised once and stored on our server; it is not recordings of people. Nothing you do here is sent to Microsoft.
DigitalOcean provides the server in Sydney. It stores what's on the server, and weekly copies of its disk for four weeks, which hold the access logs as they were that day; it doesn't use them for anything else. No other service sees anything from this site.
This site links to tinglilab.com, which explains the full TingliLab, and to the full lab itself at mandarin.lexlovers.com. That one has accounts, and its own privacy statement.
TingliLab is made by Ranjan Chaudhuri in Canberra, Australia; in this statement "we" means Ranjan Chaudhuri. Questions, or anything you'd like removed from the logs before they age out: hello@tinglilab.com.
Version 3 (October 2026): while the page is open it asks now and then which version is live, so it can tell you when there's a new one (see Server logs); nothing else changed.
Version 2 (October 2026): the contact address is now hello@tinglilab.com; nothing else changed.
Version 1 (October 2026): the first version, for the tone lab's opening. A new use of data will mean a new version, with the date and what changed.