diff --git a/dxlibex/basic_types.hpp b/dxlibex/basic_types.hpp
index 2aaa240..7e6160d 100644
--- a/dxlibex/basic_types.hpp
+++ b/dxlibex/basic_types.hpp
@@ -11,6 +11,7 @@
 #include "dxlibex/basic_types/point3d.hpp"
 #include "dxlibex/basic_types/size.hpp"
 #include "dxlibex/basic_types/tchar.hpp"
+#include "dxlibex/basic_types/bel.hpp"
 namespace dxle {
 
 	//operators betwin point_c and size_c
diff --git a/dxlibex/basic_types/bel.hpp b/dxlibex/basic_types/bel.hpp
new file mode 100644
index 0000000..fe7e15f
--- /dev/null
+++ b/dxlibex/basic_types/bel.hpp
@@ -0,0 +1,24 @@
+/*=============================================================================
+Copyright (C) 2015-2016 DxLibEx project
+https://github.com/Nagarei/DxLibEx/
+
+Distributed under the Boost Software License, Version 1.0.
+(See http://www.boost.org/LICENSE_1_0.txt)
+=============================================================================*/
+#ifndef DXLE_INC_BASIC_TYPES_BEL_HPP_
+#define DXLE_INC_BASIC_TYPES_BEL_HPP_
+#include <limits>
+#include <ratio>
+#include <utility>
+#include "dxlibex/type_traits/is_ratio.hpp"
+#include "dxlibex/type_traits/enable_if.hpp"
+namespace dxle {
+	typedef std::ratio<1, 10000> myrio;
+	namespace sound_units {
+		template<typename T, typename Period, enable_if<is_ratio<Period>::value, nullptr_t> = nullptr>
+		class bel {
+
+		};
+	}
+}
+#endif //DXLE_INC_BASIC_TYPES_BEL_HPP_
diff --git a/dxlibex/type_traits.hpp b/dxlibex/type_traits.hpp
index ef250e7..493e78e 100644
--- a/dxlibex/type_traits.hpp
+++ b/dxlibex/type_traits.hpp
@@ -17,5 +17,6 @@
 #include "dxlibex/type_traits/is_nothrow.hpp"
 #include "dxlibex/type_traits/is_representable.hpp"
 #include "dxlibex/type_traits/is_well_format.hpp"
+#include "dxlibex/type_traits/is_ratio.hpp"
 
 #endif//#ifndef DXLE_INC_TYPE_TRAITS_HPP_
diff --git a/dxlibex/type_traits/is_ratio.hpp b/dxlibex/type_traits/is_ratio.hpp
new file mode 100644
index 0000000..4a656b2
--- /dev/null
+++ b/dxlibex/type_traits/is_ratio.hpp
@@ -0,0 +1,17 @@
+/*=============================================================================
+Copyright (C) 2015-2016 DxLibEx project
+https://github.com/Nagarei/DxLibEx/
+
+Distributed under the Boost Software License, Version 1.0.
+(See http://www.boost.org/LICENSE_1_0.txt)
+=============================================================================*/
+#ifndef DXLE_INC_TYPE_TRAITS_IS_RATIO_HPP_
+#define DXLE_INC_TYPE_TRAITS_IS_RATIO_HPP_
+#include <ratio>
+#include <type_traits>
+#include <cstdint>
+namespace dxle {
+	template <typename T> struct is_ratio : std::false_type {};
+	template <std::intmax_t N, std::intmax_t D> struct is_ratio<std::ratio<N, D>> : std::true_type {};
+}
+#endif //DXLE_INC_TYPE_TRAITS_IS_RATIO_HPP_