I left 5 stars because it uses to work really well. But not longer works at all since WaterFox 5.0. It no longer mute new tabs.

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.

Hay addons que tienen ochentamil opciones y van fatal. Esta, en cambio, para lo que hace que es sencillamente poner en silencio automáticamente las pestañas nuevas que abres, va genial. Es una de las pocas extensiones de las que no he buscadp alternativas porque como digo, genial.

bugs... Seems to mutes the wrongs tabs with no icon available.

Fantastic. Simply does what it needs to do. I would add an option to make the "muted" tab icon transparent though, it attracts too much attention.

Completely purrrfect for private porn watching :)

Edit: This is something of a bug in Firefox itself. If I launch a tab with Flash, but don't "allow" the flash to run, and then mute the tab manually via Firefox and THEN click the flash element and allow it to run, the audio will still play and not be muted. I'm not sure it's possible for this add-on to avoid this problem since it is only possible to mute the tab correctly AFTER the flash has been allowed to run.

I'm having the same problem as an earlier reviewer where new tabs with FLASH components are not muted at first. The tab will show the muted symbol, but sound will still play. If I unmute and then mute again, then the tab will actually be muted. Normal tabs which use HTML5 for media ARE automatically muted properly.

Hello I downloaded this addon for the use to have all my private-windows muted by default. However, the icon appears that they are muted, which they are not, I must unmute and then mute to have that specific tab muted

"Must have" ;)

Very good work

Make sure to go to settings and check the for normal window box which is disabled by default which is really dumb if you ask me.

Exactly what i was looking for, very nice!

Could you add a feature so that one would be able to add exception like:

youtube.com/*
randomdomain.eu

YAY!! The CNET-Download website has been driving me CRAZY For Years with their Idiotic Video that (Aggravatingly!!) Auto-Plays Every Time you visit their site. Now, that idiot site is blessedly SILENT! Thank You to the Author of this Great Extension!

Does exactly what I wanted from the extension. A whitelist feature would be very welcome but a luxury I can live without.

Works with the new Firefox Quantum. Easy to use.