Enumerating and Playing System Sounds from Delphi code

To play a system sound ("application even" or "system even" as called by MS), you can call the PlaySound API function, available in the mmsystem unit.

The PlaySound function plays a sound specified by the given filename, resource, or system event. System event are, in general, associated with a sound in the registry.

Registered system sounds are located under the "AppEvents\Apps" key under HKEY_CURRENT_USER in the Registry database.

Here's how to play the "System Question" system sound:

 uses MMSystem, ...
 
 PlaySound('SystemQuestion', 0, SND_ALIAS or SND_ASYNC) ; 

Note: Using the SND_ASYNC flag the sound is played asynchronously and PlaySound returns immediately after beginning the sound playback. SND_ALIAS tells the PlaySound function that the first parameter is a system-event alias. Note (also): the actual sound refrences are stored in HKEY_CURRENT_USER\AppEvents\Schemes\Apps\.Default.

Listing all System/Event Sounds

Now that you know how to play a system sound, here's how to get the list of all the registered sounds in Windows:

Drop a TButton (name: "Button1") and a TListBox (name: "ListBox1") on a Delphi form (name: "SystemSoundPlayerForm"). Handle the Form's OnCreate and Button's OnClick events as:

 uses MMSystem, Registry, ... 
//Button1 ... OnClikc
 procedure TSystemSoundPlayerForm.Button1Click(Sender: TObject) ;
 var
    soundAlias : string;
 begin
    if ListBox1.ItemIndex = -1 then
    begin
      ShowMessage('Select a sound alias from the list...') ;
      Exit;
    end;
 
    soundAlias := ListBox1.Items[ListBox1.ItemIndex];
 
    PlaySound(PAnsiChar(soundAlias), 0, SND_ALIAS or SND_ASYNC) ;
 end;
 
 //SystemSoundPlayerForm ... OnCreate
 procedure TSystemSoundPlayerForm.FormCreate(Sender: TObject) ;
 var
    reg : TRegistry;
 begin
    reg := TRegistry.Create;
    try
      reg.RootKey := HKEY_CURRENT_USER;
 reg.OpenKeyReadOnly('\AppEvents\EventLabels') ;
      reg.GetKeyNames(ListBox1.Items) ;
    finally
      reg.Free;
    end;
 end; 

Select a sound alias from the list and hit the play button ...

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