• Please note: these advanced settings may make troubles (ex: let Firefox crash),
  if you don't have interest to write custom code, directly pick items from Usage Examples would be a good idea.
• Advanced users, or people like to play, please continue to read Setting Summary for more info.

Usually we just fill topic or event type into the "event" field of Noise Edit window,
for example, dblclick will capture double clicking events.
And what is called Event Filtering, is to append an & with filter expression after the string,
then Noise will evaluate the result of the expression when events happen, and play sounds only if the result is true.
For example, dblclick&event['target'].tagName=='H1' checks if the clicked target is a H1 element, if so, continue to play a sound.

In the inner implementation of Noise 1.0,
the mentioned & with filter expression will become a function named filtertFx which will be called when events happen,
and parameters (event object, or subject and data objects) relevant to the event will be passed to it, and available for evaluating.

More detailed description:

observe: function(subject, topic, data) {
  try {
    if( filtertFx(subject,data) ) Noise.play( i['se'] );
  } catch(e) { dump('Noise: '+e); }
}

this.listeners[i['urn']] = function(event) {
  try {
    if( filtertFx(event) ) Noise.play( i['se'] );
  } catch(e) { dump('Noise: '+e); }
}

Type: 1 = Event topic 2 = Browser Event 3 = Window Event

ps. example may not available on old versions of Noise.

• Observer Notifications - MDC
• Table Of Errors - MDC
• Mozilla Error Lookup
• Document Object Model Events - Complete list of event types - W3C