Как управлять звуком правой и левой колонок с помощью TrackBar?

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.FormCreate(Sender: TObject);
var a,b:integer;
begin
a:=GetWaveVolume shr 16;
b:=GetWaveVolume-(GetWaveVolume shr 16)shl 16;
sb2.Position:=a;
sb.Position:=b;
caption:=inttostr(a)+'<=>'+inttostr(b);
end;

procedure TForm1.sbChange(Sender: TObject);
begin
SetWaveVolume(MakeLong(sb.Position,sb2.Position)); 
caption:=inttostr(sb.Position)+'<=>'+inttostr(sb2. Position);
end;