diff --git a/df.d_interface.xml b/df.d_interface.xml
index f8fee032d..fcc002ec8 100644
--- a/df.d_interface.xml
+++ b/df.d_interface.xml
@@ -17,6 +17,7 @@
             <vmethod name='toggle'/>
             <vmethod name='decrease'/>
             <vmethod name='increase'/>
+            <vmethod ret-type='bool' name='is_on'/>
             <vmethod is-destructor='true'/>
         </virtual-methods>
     </class-type>
diff --git a/df.dfaudio.xml b/df.dfaudio.xml
new file mode 100644
index 000000000..20551dffe
--- /dev/null
+++ b/df.dfaudio.xml
@@ -0,0 +1,18 @@
+<data-definition>
+    <struct-type type-name='dfaudio_environment_state'>
+        <int32_t name='biome' comment='enum'/>
+        <int32_t name='weather' comment='enum'/>
+        <int32_t name='surroundings' comment='enum'/>
+        <int32_t name='elevation'/>
+        <s-float name='occlusion'/>
+        <s-float name='evilness'/>
+        <s-float name='savagery'/>
+    </struct-type>
+</data-definition>
+
+<!--
+Local Variables:
+indent-tabs-mode: nil
+nxml-child-indent: 4
+End:
+-->
diff --git a/df.g_src.init.xml b/df.g_src.init.xml
index 658e9c3c2..e48ad13fd 100644
--- a/df.g_src.init.xml
+++ b/df.g_src.init.xml
@@ -90,10 +90,12 @@
         <int32_t name='volume_music_fort'/>
         <int32_t name='volume_ambience_fort'/>
         <int32_t name='volume_sfx_fort'/>
+        <int32_t name='volume_ui_fort'/>
         <int32_t name='time_between_songs_fort'/>
         <int32_t name='volume_music_adv'/>
         <int32_t name='volume_ambience_adv'/>
         <int32_t name='volume_sfx_adv'/>
+        <int32_t name='volume_ui_adv'/>
         <stl-string name='title_music_str'/>
     </struct-type>
 
diff --git a/df.g_src.music_and_sound_g.xml b/df.g_src.music_and_sound_g.xml
index 763361194..554aaabec 100644
--- a/df.g_src.music_and_sound_g.xml
+++ b/df.g_src.music_and_sound_g.xml
@@ -87,6 +87,8 @@
         <static-array type-name='int32_t' count='3' name='play_history'/>
         <static-array type-name='int32_t' count='3' name='neutral_card_history'/>
 
+        <compound type-name='dfaudio_environment_state' name='environment_active'/>
+
         <int32_t name='ambience_active'/>
         <int32_t name='ambience_fading'/>
         <int32_t name='ambience_active_channel'/>