react-native-sound-level

A package to dynamically measure sound input level in React Native applications. Can be used to help user to adjust microphone sensitivity.

Works with current React Native versions, including the New Architecture (via the built-in interop layer). Requires RN 0.60+ for autolinking.

Installation

Install the npm package:

npm i react-native-sound-level --save

On iOS you need to add a usage description to Info.plist:

<key>NSMicrophoneUsageDescription</key>
<string>This sample uses the microphone to analyze sound level.</string>

On Android the RECORD_AUDIO permission is merged into your app's manifest automatically. You still need to request the permission from the user at runtime (see Usage below).

Usage

1. Request permission to access microphone, handle the UI by yourself. You may use react-native-permissions package or simply PermissionsAndroid module.
2. Configure the monitor and start it.
3. Makes sense to stop it when not used.

import RNSoundLevel from 'react-native-sound-level'

const MONITOR_INTERVAL = 250 // in ms

const requestPermission = async () => {
  // request permission to access microphone
  // ...
  if (success) {
    // start monitoring
    RNSoundLevel.start()

    // you may also specify a monitor interval (default is 250ms)
    RNSoundLevel.start(MONITOR_INTERVAL)

    // or add even more options
    RNSoundLevel.start({
      monitorInterval: MONITOR_INTERVAL,
      samplingRate: 16000, // default is 22050
      allowHapticsAndSystemSoundsDuringRecording: true, // iOS 13+ only, default is false
    })
  }
}

useEffect(() => {
  RNSoundLevel.onNewFrame = (data) => {
    // see "Returned data" section below
    console.log('Sound level info', data)
  }

  return () => {
    // don't forget to stop it
    RNSoundLevel.stop()
  }
}, [])

Returned data

{
  "id",             // frame number
  "value",          // sound level in dBFS, see "Understanding the values"
  "rawValue"        // raw level value, OS-dependent
}

Understanding the values

value is expressed in dBFS (decibels relative to full scale): 0 is the maximum level the microphone can deliver and -160 is silence. It is not an absolute dB SPL reading — a phone microphone is not calibrated for that, so this library cannot tell you that a sound is "50 dB loud". It is well suited for relative measurements: level meters, voice activity indication, adjusting microphone sensitivity and similar tasks.

On Android rawValue is the maximum PCM amplitude since the previous frame (0..32767, i.e. the range of signed 16-bit audio). On iOS rawValue equals value.

Getting constant value: -160, rawValue: 0? This almost always means the microphone permission was not granted. Request RECORD_AUDIO (Android) at runtime and make sure NSMicrophoneUsageDescription is present (iOS) — on current React Native versions start() rejects with a descriptive error code in this case, so check its rejection too.

Monitoring in background

The library keeps measuring only while the OS lets your app record:

• iOS: add the audio background mode to Info.plist (UIBackgroundModes → audio), otherwise recording is suspended shortly after the app goes to background.
• Android: run a foreground service while monitoring. Starting with Android 14 (API 34) the service must declare android:foregroundServiceType="microphone" and your app needs the FOREGROUND_SERVICE_MICROPHONE permission. Note that Android does not allow starting microphone access from the background — start monitoring while the app is in the foreground.

Manual installation on iOS (no autolinking)

In XCode, in the project navigator:

* Right click _Libraries_
* Add Files to _[your project's name]_
* Go to `node_modules/react-native-sound-level`
* Add the `.xcodeproj` file

In XCode, in the project navigator, select your project.

* Add the `libRNSoundLevel.a` from the _soundlevel_ project to your project's _Build Phases ➜ Link Binary With Libraries_

Installation on Ubuntu (react-native-desktop)

⚠️ The Qt-based react-native-desktop project is no longer maintained upstream; the desktop module is kept as-is and is not actively supported.

1. Add to package.json: "desktopExternalModules": [ "node_modules/react-native-sound-level/desktop" ]
2. You may need to make QT's multimedia library accessible for linker sudo ln -s $YOUR_QT_DIR/5.9.1/gcc_64/lib/libQt5Multimedia.so /usr/local/lib/libQt5Multimedia.so