Turn every phone into a gunshot witness.
Roundsift is a consumer mobile network that listens for impulse signatures consistent with firearm discharge, fingerprints what it hears, corroborates across nearby phones, and produces a verifiable record: when, where, and what was heard.
- Coverage
- Where ShotSpotter is not.
- Latency
- ≈ 3s to confirm
- Battery
- ≈ 1.4% / hr
Four steps, all on-device or peer-confirmed.
Nothing from your microphone leaves the phone until an acoustic fingerprint matches an impulse signature. Then nearby phones either confirm it — or don’t.
- step 01ListenAn on-device decibel + spectral analyzer watches the microphone in the background, looking for the impulse signature of a firearm discharge — not loud noises in general.
- step 02FingerprintMatching events are fingerprinted against a library of acoustic profiles. Where the profile permits, Roundsift estimates a likely weapon family — 9mm, intermediate rifle, 12-gauge, .45.
- step 03CorroborateWhen several phones on the same block register a matching impulse within seconds, their GPS + timestamps triangulate the source, and the event is upgraded to confirmed.
- step 04RecordEvery event — confirmed or partial — becomes a sealed, verifiable record: time, place, what was heard, which phones heard it, and what they agree on. Yours to use, on request, for 911, claims, or testimony.
Built for the geography fixed sensors don’t reach.
Municipal acoustic arrays — the kind built and operated by SoundThinking — are excellent, and Roundsift is not trying to replace them where they exist. The problem is everywhere else: the long tail of blocks, parks, transit, and rural roads that a sensor mesh can’t economically cover. That’s where a phone already in someone’s pocket is most useful.
Roundsift accepts the harder technical problems that come with that choice — smartphone microphone quality, ambient noise classification, battery cost, and the limits of GPS triangulation versus a dedicated mesh — in exchange for vastly wider coverage.
No municipal acoustic array. Just homes — and now, just phones.
Long, linear corridors that a fixed mesh can’t economically cover.
Trains, platforms, bus stops — areas where one shot can affect many riders.
Beyond the gates and the Blue-Light phones: the surrounding streets.
Where response time is everything and infrastructure thins out fast.
Four audiences that already carry the sensor.
A verifiable record you can use.
Victims and witnesses receive a record of when, where, and what they heard — useful for a 911 call, an insurance claim, an investigative timeline, and courtroom testimony. Records are time-stamped, GPS-tagged, sealed, and reproducible.
- 01stagePhoneGPS + timestamp
- 02stageFingerprintCaliber + match %
- 03stageCorroborationN phones · span
- 04stageSealed recordVerifiable · exportable
The network is its coverage. The more ears, the sharper the picture.
Roundsift is rolling out pilots in seven metros this spring. Request an invite and we’ll get back to you with a beta build, an instrument-test plan for your environment, and partner-side integrations if you’re a public-safety team.
Questions, security research, or press: roundsift@polsia.app