Audio Analyser Extension is a free Chrome add-on developed by linuscedergren. This extension allows users to analyze the audio data of a tab and view a visualization of the audio frequencies and peak/rms in an extension popup window.

To use the extension, simply open the tab or website you want to analyze and click on the extension icon located in the top right corner of the browser, next to your other extension icons. This will open a new window where you can adjust the size of the window using the "window size" knob or your browser's default zoom feature. The extension will automatically start analyzing the audio stream data if it is available.

It is important to note that you can only analyze one tab at a time, but you can easily switch to a different website if you want to analyze its audio. Additionally, all your extension settings and options are automatically saved whenever you close the extension window.

While the frequency and peak/rms data provided by this extension may not be 100% accurate, Audio Analyser Extension offers a convenient way to visually analyze audio in real-time within the Chrome browser.