Изменение громкости звуков в Windows

uses MMSystem;

function GetWaveVolume: DWord;
var Woc : TWaveOutCaps;
    Volume : DWord;
begin
  result:=0;
  if WaveOutGetDevCaps(WAVE_MAPPER, @Woc, sizeof(Woc)) =
       MMSYSERR_NOERROR then begin
    if Woc.dwSupport and WAVECAPS_VOLUME = WAVECAPS_VOLUME then begin
      WaveOutGetVolume(WAVE_MAPPER, @Volume);
      Result := Volume;
    end;
  end; 
end;

procedure SetWaveVolume(const AVolume: DWord);
var Woc : TWaveOutCaps;
begin
  if WaveOutGetDevCaps(WAVE_MAPPER, @Woc, sizeof(Woc)) =
       MMSYSERR_NOERROR then begin
    if Woc.dwSupport and WAVECAPS_VOLUME = WAVECAPS_VOLUME then
      WaveOutSetVolume(WAVE_MAPPER, AVolume);
  end;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  Beep;
end;

procedure TForm1.Button2Click(Sender: TObject);
var LeftVolume: Word;
    RightVolume: Word;
begin
  LeftVolume := StrToInt(Edit1.Text);
  RightVolume := StrToInt(Edit2.Text);
  SetWaveVolume(MakeLong(LeftVolume, RightVolume));
end;

procedure TForm1.Button3Click(Sender: TObject);
begin
  Caption := IntToStr(GetWaveVolume);
end;