What is the "Sound Level Meter" extension and how does it work?

This extension is designed to provide a live graph of the environmental noise around the user microphone. This data is collected only when the extension interface is open either in the browser popup or as a browser tab. The extension installs an AudioWorkletProcessor node to monitor all input channels available (mono, stereo, ...) and then generates the square root of the mean (average) value (RMS) from these time-based sound levels. The RMS value is then sent to the main thread and the decibel value is calculated from a fixed volume reference. This value is displayed in the interface and is stored for displaying statistical data such as min, max, and average values later. This extension keeps the 100 last records and finds the average value from them. Note that for this extension to work you need to allow the extension to record from your microphone. The permission is displayed on the first run.

What's new in this version?

Please check the Logs section.

Why this extension requires microphone permission? and how can I allow this permission?

This permission is requested after the first use. When you install the extension click on the action button once. A new page opens and permission is requested on the top left side of the page like all other web apps that need such permission. When permission is granted, the extension starts to record samples from your microphone and uses these samples to find the noise level in dB. Note that you can always visit the "chrome://settings/content/microphone" page on a chromium browser to withdraw extension permissions. Also, note that this extension does not send any data to any server whatsoever.

How does this extension calculate the noise level in dB?

The extension installs an AudioWorkletProcessor node which gets called when the microphone has new raw data. From these raw data (might be multiple channels), the extension finds the RMS value of the volume and then compares this value with a referenced volume level to convert the volume value to dB.