Privacy policy
Your audio never leaves your device.
Last updated: 7 May 2026
Decibel is built on a simple principle: audio is processed on your iPhone, in real time, and immediately discarded. This document describes, in plain terms, what Decibel does and does not do with data on your device.
TL;DR
- Decibel uses your iPhone's microphone only to compute live sound-pressure levels. Audio samples are processed in memory and immediately discarded.
- No audio is recorded, no audio is stored, no audio is transmitted.
- Decibel does not collect personal data. It has no user accounts, analytics, advertising, tracking, or third-party SDKs.
- Decibel makes no network requests. It works fully offline.
- Two pieces of data persist on your device, both in app-private storage: your calibration offset, and a local list of past recording sessions (timestamp, duration, peak dB, average dB — not audio).
What the microphone is used for
When you open Decibel, it opens an audio input stream and computes the root-mean-square level of incoming audio frames in real time. The result is converted to an estimated sound-pressure level in decibels and shown on screen. Each audio buffer is processed and discarded; no buffer is ever written to disk or sent anywhere.
The microphone permission you grant on first launch (the iOS
NSMicrophoneUsageDescription) is the only sensitive
permission Decibel requests. You can revoke it at any time from
iOS Settings → Privacy & Security → Microphone → Decibel.
What the "recording" feature does
The big red record button does not record audio. It starts a measurement session — Decibel begins tracking the peak and average dB levels and a rolling 15-second trace of the live reading. When you stop the session, Decibel saves a small summary to your device:
- A unique identifier (UUID) for the session
- The start time
- The duration in seconds
- The peak dB level reached
- The average dB level over the session
That's it. No audio, no waveform export, nothing identifying you. This summary is saved as a JSON file in Decibel's app-private Documents directory and is visible in the History sheet inside the app. You can delete individual sessions by swiping, or clear the entire history with the trash icon.
What is stored on your device
| Data | Where | When deleted |
|---|---|---|
| Calibration offset | UserDefaults | On uninstall, or via "Reset to default" in Calibration |
| Recording history | App Documents directory | Per-session swipe, "Clear all", or app uninstall |
| First-launch flag | UserDefaults | On uninstall |
None of this data is synced to iCloud, transmitted off-device, or shared with any third party.
What is not collected, used, or shared
- No audio recordings, audio waveforms, or audio files
- No personal information (name, email, phone, location)
- No device identifiers (IDFA, IDFV, advertising identifiers)
- No usage analytics, crash reports, or diagnostic data
- No advertising, no ad networks, no ad attribution
- No third-party SDKs or libraries that collect data
- No social-graph or contact-list access
- No network requests of any kind
Children's privacy
Decibel is rated 4+ in the App Store. It collects no information from anyone, including children.
Changes to this policy
If the app's data behaviour ever changes, this page and the
PrivacyInfo.xcprivacy manifest bundled with the
app will be updated to match before any new build is submitted
to the App Store.
Contact
Questions about this policy: andreehultgren@gmail.com.