After installed and restarted Firefox, sounds should be ready to response events.
You can try open Findbar (Ctrl + F) and find a word, when the find reaching the end of page (when hit F3 to find nexts), you can heard a "beep" sound if you try finding next.

If everything goes well, you might like to open the preference window to set what event sounds, and what sound to response the event.
See Options to understand more.

And as you can see, Noise only have boring "beep" by default.
In this moment, you must find wav files outside this package. Here are some suggestions where to get little sounds:

• Soundsnap.com: Find and Share Free Sound Effects and Loops
• ザ・マッチメイカァズ2nd 【フリー効果音素材】
• Use PSound by snailrush. To extract sounds from PS or PS2 game discs.

Preference window Usage ｜ Edit window Usage

1. After installed, go to Add-ons Manager ( Tools > Add-ons > Extensions ) and find Noise.
   Enter the Preference Window via the Option command.
2. In Preference window we have a checkbox, a tree, and some buttons.
   
   What they are?

   1. Enable Sounds:

      This globally toggle Noise sounds on/off.
      If unchecked, all sounds make by Noise will be disabled (an exception is in the Edit window, it still play sounds for testing.)
      Tip: in a browser window, you can toggle Noise by press "accel + alt + shift + N" shortcut key.

   2. Tree:

      This tree lists all events, and the sounds matching them.
      

      • Double click a row to edit it.
      • Drag and Drop a row to resort it.
      • Select an item and press Enter key to edit, or press Space key to enable/disable it.
      • Right click to show context menu. This is the only way to add a separator now.
        Select Add → Duplicate to copy current selected item.
        

   3. Buttons:

      • Add, Edit, Play, Enable/Disable, Remove are buttons to modify the tree.
      • Settings button handle the export/import/default works.
        
      • Accept, Cancel buttons do nothing other than normal.
        While accepting, all settings should apply to all windows instantly. (If not, it might be a bug, please report it.)

   4. Link to Events guide:

      This link opens a new guide window, lists all available events which were included in Noise by default.
      So if you lost old settings, or want to check if there were new features in new version, here it is:
      
      Just pick some items, they'll be appended to Preference window.

Edit window Usage ｜ Preference window Usage

1. In Preference Window, double click a row will open Edit window.
   
   Each field means:

   1. Name

      The name of item.

   2. Event

      According to different event types, this should be a topic or an event type. More info described below.

      

      Hey, please wait!
      If you don't have interest to know what the inner code working.
      Directly go to Events Reference and find what string to fill in, it would be much simpler.

      
      

      For advenced user (knows what to do if Firefox crash...) we can use "Event Filter" to futher filter events.
      Append an & with event handler expersion to the event string, will only play sound while the evaluate result is true.
      Fox example, DOMContentLoaded&event.target.baseURI=='http://127.0.0.1/' will only play sound when loading http://127.0.0.1/
      Please visit Event Filter for more information.

   3. Event type

      Noise captures events via 3 different ways:
      

      • Event topic

        Some events use nsIObserverService's notifyObservers to notify something was happened, with a topic string.
        So Noise creates nsIObserver to capture topics.
        In such a case a topic string is needed to fill in the Event field, ex: domwindowclosed.

      • Browser event

        If an event can be capture by gBrowser.addEventListener then it can make noise.
        For example click, copy, and TabOpen are valid.

      • Window event

        Similar to browser event, Noise capture these events by window.addEventListener.

   4. Sound file

      Accept string in three formats below:

      • beep

        Directly input string beep to play a platform-dependent beep.

      • system sound

        Use event:aEventId (require Gecko 1.9.2) or sys:soundAlias to play system sounds.
        For example: event:EVENT_MENU_POPUP.
        See aEventId for more information.

      • Local wav file

        Click the "Choose..." button you can get file string like C:\WINDOWS\Media\ding.wav.

        You can also use relative path, with a base directory, to manage your sounds.
        Just enable the "Use sound directory" checkbox, then "Choose..." will start from your base directory.
        Therefore we can simply use filename.wav which is much more portable!

        Note: only one base directory could be set.
        If you use relative path with a different base, original ones will lose their point.
        In fact Noise will notify you if we need to change the base.

      • Local wav file in chrome URL format

        This is also a local wav file, but the string is in Chrome URL format.
        Might be useful when packaging custom version of Noise... I'm not sure.

   5. Play

      Play the sound for testing. Even you disabled Noise globally, this sounds.

Please report bugs on use Google groups: Noise (Firefox Extension), thanks!

• I've learned very much from PopupSound Add-on by nrlz , and FireGestures Add-on by Gomita.
• In Add-ons Manager, check the About dialog to see other contributors.

1. Uninstall Noise in Add-ons Manager.
2. Everything is done here.
   But you can clean all settings below if you really like to.
3. Go to your Profiles directory, delete the file noise-mappings.rdf. That is your event-sound mapping settings.
4. In Profiles directory, delete the noise directory. That is the default base directory for parse relative paths to sound files.
5. Enter about:config, if there're extensions.noise.base, extensions.noise.enabled, extensions.noise.version and [email protected], you can delete them.

• PopupSound 0.1.5 - Customizable Popup Blocked, Link Clicked, and Download Finisihed sounds.
• Navigational Sounds 1.1.0 - Use Windows system sound settings for navigation (pages start and finish), Popup Blocked, and information bar sounds.