diff --git a/Makefile b/Makefile
index 1e82a74..942fb4a 100644
--- a/Makefile
+++ b/Makefile
@@ -195,6 +195,16 @@ $(error Invalid target: T=$(T))
 endif
 export T
 
+# Select sound language
+LANGUAGE_SOUND_FOLDER = config/_default_cfg_src_/res/$(LANG)
+ifeq ($(LANG),)
+$(error Please specify the sound language in the command line: LANG=<languageAbbrev>)
+endif
+ifeq ($(wildcard $(LANGUAGE_SOUND_FOLDER)),)
+$(error Invalid target: LANG=$(LANG))
+endif
+export LANG
+
 KBUILD_OUTPUT := $(KBUILD_OUTPUT)/$(T)
 
 # That's our default target when none is given on the command line
diff --git a/services/bt_app/Makefile b/services/bt_app/Makefile
index 684c540..e74116e 100644
--- a/services/bt_app/Makefile
+++ b/services/bt_app/Makefile
@@ -9,8 +9,7 @@ ifeq ($(VOICE_DATAPATH_TYPE),gsound)
 obj_cpp += $(patsubst $(cur_dir)%,%,$(wildcard $(cur_dir)/app_voice/app_$(VOICE_DATAPATH_TYPE)/*.cpp))
 endif
 
-obj_mp3 := $(patsubst $(cur_dir)%,%,$(wildcard ../../config/_default_cfg_src_/res/en/*.mp3))
-obj_mp3 += $(patsubst $(cur_dir)%,%,$(wildcard ../../config/_default_cfg_src_/res/cn/*.mp3))
+obj_mp3 := $(patsubst $(cur_dir)%,%,$(wildcard ../../config/_default_cfg_src_/res/$(LANG)/*.mp3))
 
 obj-y := $(obj_mp3:.mp3=.snd.o) $(obj_mp3:.mp3=.snd.cpp) $(obj_c:.c=.o) $(obj_s:.S=.o) $(obj_cpp:.cpp=.o)