SoundSphere by dzl

SoundSphere is a per-tab volume booster and equalizer. Boost quiet tabs up to 800%, shape the sound with Voice and Bass modes or a 10-band EQ, and see which tabs are playing audio. Everything is processed locally in Firefox.

WHAT'S NEW IN 1.3.1
• Boost and EQ now work on Bandcamp, SoundCloud and other sites that stream audio from another domain
• Spotify: volume and mute now work; EQ, Voice and Bass are greyed out there with an explanation (see Limitations)
• 100% with a flat EQ now sounds exactly like SoundSphere being off
• Opening the popup no longer changes a tab's audio on its own
• Lowering the volume never makes a player louder than its own setting, and resetting gives the player its volume back
• Remembered tab volumes no longer carry over to unrelated tabs after a restart
• Better screen reader and keyboard support

FEATURES
• Volume from 0% to 800% per tab (600% max if you turn off overdrive)
• A soft limiter keeps boosted audio from clipping harshly
• Quick modes: Default, Voice (clearer speech), Bass (more low end)
• 10-band EQ (31 Hz to 16 kHz) with presets: Flat, Rock, Pop, Hip-Hop, Jazz, Classical, Electronic, Vocal, Live Clean, Bass Boost, Treble Boost, V-Shape, plus your own custom setting
• List of tabs playing audio; click one to jump to it
• Optional toolbar badge showing how many tabs are playing (desktop)
• Remember volume per tab for the current session, or use one global volume; option to start new tabs at 100%
• Also works on Firefox for Android

HOW IT WORKS
Open the popup on a tab and move the slider, pick a mode or set the EQ. Opening the popup alone changes nothing. SoundSphere processes the page's own audio and video players with the Web Audio API.
• If a video started playing before you clicked anything on the page, Firefox may ask for one click on the page before boost and EQ can start
• Bandcamp and similar sites: the track reloads once (about a second) the first time you boost, then plays boosted

LIMITATIONS
• Protected (DRM) audio, such as Spotify Web: Firefox does not let add-ons process this audio, so only volume from 0% to 100% and mute are available. Boost, EQ and Voice/Bass are greyed out with a short explanation.
• Firefox's own pages (about: pages, addons.mozilla.org) can't be controlled.

PERMISSIONS
• Access your data for all websites: lets SoundSphere adjust audio on whichever site you use it on. It only looks at the page's audio and video players; nothing from the page is stored or sent anywhere.
• Access browser tabs: lists the tabs that are playing audio and switches to one when you click it.
• Storage: saves your settings.
• Network request rules (no prompt): when you boost a tab whose audio comes from another domain, SoundSphere adds a CORS header to media in that tab only, so the audio can be processed. The rule is removed when the tab closes.

PRIVACY
• All audio processing happens on your device; audio is never recorded or saved
• No analytics, tracking, ads or remote code; SoundSphere makes no network requests
• Privacy policy: https://ripdzl.github.io/SoundSphere/privacy.html

Source code and issues: https://github.com/ripDZL/SoundSphere
Also available for Chrome: https://chromewebstore.google.com/detail/soundsphere/bmdclfobmjbikodcmbdhmfoadboimaln

High boost levels can distort audio and may damage hearing or speakers. Start low, especially with headphones.