SoundSphere by dzl

SoundSphere – per-tab volume booster for Firefox

SoundSphere lets you push quiet tabs louder, shape the sound, and quickly see which tabs are actually making noise.

It sits in your toolbar and gives you a simple popup with a volume slider, audio modes, and a list of tabs that are currently playing audio. Everything runs locally in your browser – there are no trackers, no analytics, and no external font or script requests.

What it does

Boost tab audio up to 800% (when there is headroom)

Choose between Default, Voice boost, and Bass boost modes

Optional Experimental Overdrive mode for extra punch (may distort)

Show how many tabs are audible via a badge on the toolbar icon

Quickly jump to any playing tab from the popup

Remember volume per tab or use a single global volume

Volume and audio modes

The slider ranges from 0% to 800%

0% – mute

100% – original volume

100–600% – strong boost, generally usable

600–800% – “use at your own risk” range that can clip or distort

Voice boost uses a high-shelf EQ to make speech clearer in videos, streams, and calls.

Bass boost lifts the low end for music and games.

Experimental Overdrive adds compression to squeeze a bit more perceived loudness out of already loud sources. It can change the character of the sound and is intentionally opt-in.

Tab list and badge

The toolbar badge can show how many tabs are currently playing audio.

The popup lists each audible tab with its favicon and a shortened title.

Click a tab in the list to focus it instantly.

You can turn the badge off in the settings if you prefer a cleaner toolbar.

Settings

SoundSphere has a small set of options you can reach either from:

The gear icon in the popup, or

The extension’s Preferences page in about:addons

Available options:

Show or hide the badge count on the toolbar icon

Remember volume per tab or use one global volume level

Always start new tabs at 100%

Enable or disable Experimental Overdrive mode

These preferences are stored using Firefox’s sync storage so they can follow you across profiles that share the same Firefox account, if you choose.

Permissions and privacy

SoundSphere requests:

tabs / activeTab – to see which tabs are active and playing audio, and to send volume/mode messages to them

storage – to save your settings and optional per-tab volume

<all_urls> – to be able to process audio on any site you choose to use it on

The extension:

Does not send any data to external servers

Does not include analytics or tracking

Does not inject remote scripts or load external fonts (the UI font is bundled locally)

All audio processing happens in your browser using the Web Audio API.

Known limitations

SoundSphere works best on “normal” HTML5 audio and video players: YouTube, embedded videos, basic audio players, etc.

Some sites use very complex Web Audio pipelines and aggressive mastering (for example, some music-streaming or DJ-style players). On those sites:

Mute, Voice/Bass modes, and Overdrive may still work,

But there might be less “extra” headroom available above 100% volume,

Pushing the slider high can result in more distortion rather than a huge jump in perceived loudness.

If you need guaranteed global loudness for all system audio, a system-level solution (like an OS-level EQ or virtual mixer) is still the most reliable option. SoundSphere is designed to be a clean, per-tab, browser-side tool that plays nicely with most sites.