uses mmsystem;

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

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