Examine source code of HowLoud — Sound Meter

{
  "manifest_version": 3,
  "name": "HowLoud — Sound Meter",
  "version": "1.0.0",
  "description": "Measure ambient noise in your browser. A quick decibel estimate from your microphone — nothing is recorded or stored.",
  "action": {
    "default_title": "HowLoud — Sound Meter",
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "howloud@lukichev.biz",
      "strict_min_version": "109.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "icons": {
    "16": "icons/16.png",
    "32": "icons/32.png",
    "48": "icons/48.png",
    "64": "icons/64.png",
    "128": "icons/128.png"
  }
}