How we built HearAlong, an app that turns phone and earbuds into a hearing helper.
HearAlong amplifies speech and softens background noise through the earbuds you already own, and can caption or translate what people say. It went from the first line of code to Google Play in 29 days.
- Platform
- Android
- Built with
- Kotlin, Jetpack Compose and a C++ audio engine
- Started
- 18 September 2026
- Live
- Google Play on 17 October 2026
The goal
Conversations are hard to follow for many people, and a dedicated device is not always an option. We wanted to make a phone and a pair of earbuds do the job, with controls simple enough for someone who doesn't like settings screens.
What we built
- Live amplification with noise reduction, a boost for distant voices and a hearing-safe limiter that caps the output.
- A conversation mode that learns your own voice on the phone and turns itself down while you talk.
- Live captions and translation between languages, all on the phone.
- Safety rules built in: the app refuses to start without headphones and never plays through the phone's speaker.
HearAlong is not a medical device or a hearing aid, and its store listing and website say so plainly.
How it is built
Real-time audio needs very little delay, so this one is native Android. The sound is processed by a C++ audio engine built on Google's Oboe library, and the screens are written in Kotlin with Jetpack Compose. Speech recognition (Vosk) and translation (Google ML Kit) run on the phone, so the audio never leaves it.
Timeline
- 18 SepFirst codeThe very first commit is already a working sound amplifier.
- 30 SepTranslate tabLive captions and translation modes join the amplifier.
- 14 OctSubmitted to Google PlayWith the listing, the data-safety answers and Google's declaration for apps that keep the microphone running.
- 17 OctLive in productionAvailable in 178 countries on Google Play.
What we'd tell a client
- Pick the tool for the job. Most of our apps share one codebase across iPhone and Android. Live audio can't, so we chose native code for this one.
- Write the limits down. Health-adjacent apps need clear wording about what they are not. For HearAlong it is on the store listing and across the website, including the terms.
Get the app
Free to download, with optional tips. Android only. See also HearAlong on our products page, or how we build apps for clients.
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