var soundmaster = m_Map.SoundMaster();

.... 

if (soundmaster.IsActive()) {
	alert("SoundMsater 활성");
} else {
	alert("SoundMaster 비활성");
}

#include "CXSoundMaster.h"

CXSoundMaster soundmaster = m_Map.GetSoundMaster();

....

if (soundmaster.IsActive()) {
	AfxMessageBox(_T("SoundMsater 활성"));
} else {
	AfxMessageBox(_T("SoundMaster 비활성"));
}