Good extension. To remove only the "muted" icon from newer firefox version (138 and up), I add to the userChrome.css:

.tabbrowser-tab[muted] .tab-icon-overlay,
.tabbrowser-tab[muted] .tab-audio-button {
display: none !important;
}

Simple to use and so incredibly useful that it makes you wonder why browsers aren't already just doing this by default. Thank you so much! Please make a chrome version!! :)

It's a weird add-on. It affects the synchronisation between the video and audio across various video streaming sites. It brings in audio delays when active. Moreover, it automatically whitelists a website when its tab is unmuted. So further reloads do not mute the previously unmuted website by default. That setting could however be changed in the "Preferences" section of the add-on. More than relying on third party add-ons.. it's better if websites default to 50% volume while playing any media when they get freshly loaded for the very first time(before cookies save the preferred volume, set manually, for the subsequent loads).

Please allow users to configure the addon to let us see website favicons rather than the speaker icon on muted tabs. The speaker icons complicate multi-tab browsing.

I hate sites that force you to listen to their sounds. This add-on turns that off by default. It has an optional setting to remember for which sites you enable sound so you don't have to unmute them repeatedly. Have been using it for a long time and love it. Thanks for writing it, abba23!

Adds a clickable mute icon to every tab whether or not it's playing sound. Ugly clutter.

need some blacklist so only x sites are muted default.

This plugin keeps crashing ff instance

Sehr praktisch, einwandfreie Funktion

Works great at what it is supposed to do but it it way too easy to accidentally unmute a tab when switching tabs. When you accidentally unmute a tab, you can't even quickly remute it in the same way but have use a right click menu every time. Even just having this be the opposite would be more helpful.

Only thing that could make this better is if it could mute/unmute sites based on if a certain audio device (such as headphones) are connected or not. Granted, I'm on Windows, so I don't know if that'd work on other OSes, but it'd be nice to have.

so good

Thank you so much - muting domains instead of tabs was the number one Chrome feature I missed. This extension does exactly what I wanted and improves my browsing experience a lot.

I just added this to userChrome.css to remove the ugly "MUTED" label by Firefox:
.tab-secondary-label[muted] {
display: none !important;
}

When I press ctrl+m it mutes/unmutes multiple tabs from the same domain, even though they have different subfolder address. I expected only the current tab to be affected and keep every other tab muted. Would be nice to have different keybinds to whitelist domain and mute/unmute current tab.

Thank you. Works well.

However, with most/all tabs muted, the "muted" icon next to each tab is taking space, it's visually noisy and it hides/replaces the site icon.

Remedy: Hide "muted" icon unless a tab is currently playing sound.

How? create "userChrome.css" file with the following content:
@namespace url(http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul);
.tab-icon-overlay:not([soundplaying]) {
display: none;
}
.tab-icon-image:not([soundplaying]) {
opacity: 1 !important;
}

Save that file in chrome folder right under your Firefox profile folder. To locate that, open Firefox special URL about:support and see "Profile Directory". See also https://www.reddit.com/r/FirefoxCSS.

As someone who forgets he left his speakers on, this addon has been a lifesaver.