I added the music Interlude to ambience_modpack (It was compressed) and added it into the init.lua config and into the soundlicenses.txt informations

mods/ambience_modpack/ambience/init.lua

@@ -217,6 +217,7 @@ local music = {
 	{name="StrangelyBeautifulShort", length=3*60+.5, gain=music_volume*.7},
 	{name="Loneliness", length=3*60+51, gain=music_volume*.9},
 	{name="AvalonShort", length=2*60+58, gain=music_volume*1.4},
+	{name="Interlude", length=2*60+15, gain=music_volume*1.6},
 	--{name="mtest", length=4*60+33, gain=music_volume},
 	--{name="echos", length=2*60+26, gain=music_volume},
 	--{name="FoamOfTheSea", length=1*60+50, gain=music_volume},

mods/ambience_modpack/ambience/sounds/SoundLicenses.txt

@@ -13,6 +13,10 @@ These sounds are used for the Mod for Minetest; Ambiance.
 The included sounds are http://creativecommons.org/licenses/by-nc-sa/3.0/ 
 Not Used:--mtest
 
+Obani:
+--Interlude
+This sounds is under the license CC-BY-SA
+
 -----------Sound Lic:
 --Nightime Sound, Recorded by Mike Koenig, License: Attribution 3.0 http://soundbible.com/951-Nightime.html
 --Crickets At Night Sound, License: Attribution 3.0 | Recorded by Mike Koenig |http://soundbible.com/365-Crickets-At-Night.html