Privacy Policy

Last updated 11 October 2026

Sterling listens to you speak, so we take what we do with your voice seriously. This policy explains what we collect, why, where it goes and how long we keep it. The short version: your recordings are used to score your pronunciation; the only ones we keep are your assessment and the times you read its lines again, so you can hear how far you have come, and unless you turn it off we use those to train Sterling’s own speech models; your scores and your answers are kept in your account so the course can be built around you; and you can delete everything from inside the app.

Sterling is provided by Double Colourless Limited, a company registered in England and Wales, which is the data controller. You can reach us at help@sterlingaccent.com.

1. What we collect

Your account

When you sign in with Apple or Google we receive an identifier for you and, if you allow it, your name and email address. Apple may give us a private relay address instead of your real one. If you sign up with an email address, we keep the address and a securely hashed version of your password, never the password itself. The name you give us during onboarding is kept with your account and used to address you; it is included in the text sent to the language model and the speech-synthesis provider so that Sterling can greet you by name.

Your answers

During onboarding you tell us your first language, your level of English, where you want to use the accent, why you are starting, what you find hard, what you like talking about, your age group, how you describe yourself, how you found Sterling, which coach voice you prefer and how long you want to practise each day. These shape your course.

Your voice

When you record yourself in a lesson, an assessment or a conversation, the recording is sent to our server, which sends it to a pronunciation-scoring service and, for conversations, to a language model that produces Sterling’s reply and feedback. We keep the scores, the transcript of what you said and the feedback in your account.

Most recordings are deleted from our server as soon as they have been scored. Two kinds are kept in your account: the lines you read in your assessment, and the times Sterling asks you to read one of those lines again, so that you can hear your first reading beside your latest, even on a new phone. They are stored privately, only you can play them back in the app, and they are deleted with your account. A copy of your recordings also stays on your phone so you can hear yourself back, and goes when you delete the app.

Training our models

We may use the recordings kept in your account, with their scores, the text you read, and the answers you gave in onboarding about your first language, age group and how you describe yourself, to train and improve Sterling’s own speech models, such as the ones that mark your pronunciation and recognise accents. If you tell us you are under 18, this starts off and stays off unless you turn it on. Otherwise it is on unless you turn it off: in the app, go to Profile and switch off “Help improve Sterling”. When you turn it off, your recordings are deleted from our training data and are not used for training again. A model already trained on them cannot unlearn them, but no new model will be.

Before a recording is used for training, we store it without your name, your email address or your account details, under a code we keep only so that we can find and delete it if you turn training off or delete your account. We do not use your recordings to identify you, we do not sell them, and we do not give them to anyone else to train their models. When you delete your account, your recordings are deleted from our training data too. Lesson and conversation recordings are not kept, so they are never used for training.

To check that Sterling marks pronunciation fairly, people on our team may listen to a small number of kept recordings and rate them by ear. They hear the recording and the text that was read, never your name or account. The same switch covers this: turn off “Help improve Sterling” and your recordings are not listened to for this.

Your progress

Your score for each sound, the lessons you have completed, your placement result, your streak and your practice days.

Your device

To make sure requests come from the genuine Sterling app, the app uses Apple’s App Attest. We store an identifier and a public key for your device; neither identifies you personally outside Sterling.

Subscriptions

Apple handles payment. We learn whether you have an active subscription, never your card details. The service that shows our subscription offers receives an anonymous account identifier, your name and your onboarding answers so that offers can be relevant.

Technical information

Our servers keep short-lived logs of requests, including your IP address and the time, for security and to fix faults.

2. Why we use it, and on what basis

3. Who we share it with

We do not sell your data. We share it only with the services we need to run Sterling, each bound by a contract to use it only for that purpose:

We will tell you which companies these are if you ask.

Some of these providers are outside the UK. Where they are, we rely on the UK’s international data transfer agreement or its addendum to the EU standard contractual clauses, or on the provider’s certification under the UK Extension to the EU–US Data Privacy Framework, so that your data has equivalent protection.

We may also disclose information if the law requires it, or to protect the rights and safety of our users or ourselves.

4. How long we keep it

When you delete your account from the Profile tab, everything we hold about you is deleted from our systems straight away, and our providers are instructed to delete what they hold. Some may keep a copy for a short time under their own retention rules.

5. Your rights

Under UK data protection law you can ask us for a copy of your data, ask us to correct it, delete it or restrict how we use it, object to our use of it, and ask for it in a portable form. Write to help@sterlingaccent.com and we will answer within a month. You can also complain to the Information Commissioner’s Office at ico.org.uk, though we would rather you came to us first.

6. Children

Sterling is not intended for children under 13, and we do not knowingly collect their data. If you think a child under 13 has an account, tell us and we will delete it.

7. The website

sterlingaccent.com uses Google Analytics to understand how the site is used. It sets cookies (named _ga and _ga_ followed by an identifier) that recognise your browser on later visits, and sends Google the pages you view, with your IP address shortened. You can block these cookies in your browser settings or with Google’s opt-out extension without affecting the site. The network that delivers the site may also set a short-lived cookie to tell people from bots.

The accent test on sterlingaccent.com records you reading a short passage. The recording is sent in pieces to our accent model, which runs on Google Cloud in London, and the model sends back its guess. Each piece is held only while it is being heard: it is not stored, it is not linked to you, and it is not used to train any model. If the model cannot be reached, your browser hears the recording itself and nothing leaves your device.

8. Changes

We will update this policy when what we do changes. The date at the top tells you when. If a change matters to you, we will tell you in the app or by email.

9. Contact

Double Colourless Limited, help@sterlingaccent.com.