A few more audio tweaks.

src/constants.nvgt

@@ -107,6 +107,8 @@ const float FIREPIT_SOUND_VOLUME_STEP = 6.0;  // 30 dB over 5 tiles
 const int STREAM_SOUND_RANGE = 7;
 const float STREAM_SOUND_VOLUME_STEP = 4.3;  // 30 dB over 7 tiles
 
+const float TREE_SOUND_VOLUME_STEP = 4.0;  // Similar to snares for good audibility
+
 // Mountain configuration
 const int MOUNTAIN_SIZE = 60;
 const int MOUNTAIN_MIN_ELEVATION = 0;