diff --git a/Nasal/Libraries/libraries.nas b/Nasal/Libraries/libraries.nas
index 9dd5f0f8..9bf5b40b 100644
--- a/Nasal/Libraries/libraries.nas
+++ b/Nasal/Libraries/libraries.nas
@@ -448,7 +448,7 @@ controls.elevatorTrim = func(d) {
     if (systems.HYD.Psi.green.getValue() >= 1500) {
         slewProp("/controls/flight/elevator-trim", d * 0.0185); # Rate in JSB normalized (0.125 / 13.5)
     } else {
-		 slewProp("/controls/flight/elevator-trim", d * 0.0092) # Rate in JSB normalized (0.125 / 13.5)
+		slewProp("/controls/flight/elevator-trim", d * 0.0092) # Rate in JSB normalized (0.125 / 13.5)
 	}
 }
 
diff --git a/Sounds/cfm56-sound.xml b/Sounds/cfm56-sound.xml
index 75f4d669..e49487ee 100644
--- a/Sounds/cfm56-sound.xml
+++ b/Sounds/cfm56-sound.xml
@@ -544,9 +544,8 @@
 			</equals>
 		</condition>
 		<volume>
-			<property>/sim/sound/internal-custom</property>
-			<factor>-1</factor>
-			<offset>1</offset>
+			<property>/sim/sound/external-custom</property>
+			<factor>1</factor>
 		</volume>
 		<orientation>
 			<x>-1</x>
@@ -575,9 +574,8 @@
 			</equals>
 		</condition>
 		<volume>
-			<property>/sim/sound/internal-custom</property>
-			<factor>-1</factor>
-			<offset>1</offset>
+			<property>/sim/sound/external-custom</property>
+			<factor>1</factor>
 		</volume>
 		<orientation>
 			<x>-1</x>
@@ -606,9 +604,8 @@
 			</equals>
 		</condition>
 		<volume>
-			<property>/sim/sound/internal-custom</property>
-			<factor>-1</factor>
-			<offset>1</offset>
+			<property>/sim/sound/external-custom</property>
+			<factor>1</factor>
 		</volume>
 		<orientation>
 			<x>-1</x>
@@ -637,9 +634,8 @@
 			</equals>
 		</condition>
 		<volume>
-			<property>/sim/sound/internal-custom</property>
-			<factor>-1</factor>
-			<offset>1</offset>
+			<property>/sim/sound/external-custom</property>
+			<factor>1</factor>
 		</volume>
 		<orientation>
 			<x>-1</x>
@@ -668,9 +664,8 @@
 			</equals>
 		</condition>
 		<volume>
-			<property>/sim/sound/internal-custom</property>
-			<factor>-1</factor>
-			<offset>1</offset>
+			<property>/sim/sound/external-custom</property>
+			<factor>1</factor>
 		</volume>
 		<orientation>
 			<x>1</x>
@@ -699,9 +694,8 @@
 			</equals>
 		</condition>
 		<volume>
-			<property>/sim/sound/internal-custom</property>
-			<factor>-1</factor>
-			<offset>1</offset>
+			<property>/sim/sound/external-custom</property>
+			<factor>1</factor>
 		</volume>
 		<orientation>
 			<x>1</x>
@@ -730,9 +724,8 @@
 			</equals>
 		</condition>
 		<volume>
-			<property>/sim/sound/internal-custom</property>
-			<factor>-1</factor>
-			<offset>1</offset>
+			<property>/sim/sound/external-custom</property>
+			<factor>1</factor>
 		</volume>
 		<reference-dist>30</reference-dist>
 		<position>
@@ -753,9 +746,8 @@
 			</equals>
 		</condition>
 		<volume>
-			<property>/sim/sound/internal-custom</property>
-			<factor>-1</factor>
-			<offset>1</offset>
+			<property>/sim/sound/external-custom</property>
+			<factor>1</factor>
 		</volume>
 		<reference-dist>30</reference-dist>
 		<position>
diff --git a/Sounds/leapx-sound.xml b/Sounds/leapx-sound.xml
index d7ff4875..8156494f 100644
--- a/Sounds/leapx-sound.xml
+++ b/Sounds/leapx-sound.xml
@@ -458,9 +458,8 @@
 			</equals>
 		</condition>
 		<volume>
-			<property>/sim/sound/internal-custom</property>
-			<factor>-1</factor>
-			<offset>1</offset>
+			<property>/sim/sound/external-custom</property>
+			<factor>1</factor>
 		</volume>
 		<orientation>
 			<x>-1</x>
@@ -489,9 +488,8 @@
 			</equals>
 		</condition>
 		<volume>
-			<property>/sim/sound/internal-custom</property>
-			<factor>-1</factor>
-			<offset>1</offset>
+			<property>/sim/sound/external-custom</property>
+			<factor>1</factor>
 		</volume>
 		<orientation>
 			<x>-1</x>
@@ -520,9 +518,8 @@
 			</equals>
 		</condition>
 		<volume>
-			<property>/sim/sound/internal-custom</property>
-			<factor>-1</factor>
-			<offset>1</offset>
+			<property>/sim/sound/external-custom</property>
+			<factor>1</factor>
 		</volume>
 		<orientation>
 			<x>-1</x>
@@ -551,9 +548,8 @@
 			</equals>
 		</condition>
 		<volume>
-			<property>/sim/sound/internal-custom</property>
-			<factor>-1</factor>
-			<offset>1</offset>
+			<property>/sim/sound/external-custom</property>
+			<factor>1</factor>
 		</volume>
 		<orientation>
 			<x>-1</x>
@@ -582,9 +578,8 @@
 			</equals>
 		</condition>
 		<volume>
-			<property>/sim/sound/internal-custom</property>
-			<factor>-1</factor>
-			<offset>1</offset>
+			<property>/sim/sound/external-custom</property>
+			<factor>1</factor>
 		</volume>
 		<orientation>
 			<x>1</x>
@@ -613,9 +608,8 @@
 			</equals>
 		</condition>
 		<volume>
-			<property>/sim/sound/internal-custom</property>
-			<factor>-1</factor>
-			<offset>1</offset>
+			<property>/sim/sound/external-custom</property>
+			<factor>1</factor>
 		</volume>
 		<orientation>
 			<x>1</x>
diff --git a/Sounds/v2500-sound.xml b/Sounds/v2500-sound.xml
index 3fcf70ba..9654322c 100644
--- a/Sounds/v2500-sound.xml
+++ b/Sounds/v2500-sound.xml
@@ -361,9 +361,8 @@
 			</equals>
 		</condition>
 		<volume>
-			<property>/sim/sound/internal-custom</property>
-			<factor>-1</factor>
-			<offset>1</offset>
+			<property>/sim/sound/external-custom</property>
+			<factor>1</factor>
 		</volume>
 		<orientation>
 			<x>-1</x>
@@ -392,9 +391,8 @@
 			</equals>
 		</condition>
 		<volume>
-			<property>/sim/sound/internal-custom</property>
-			<factor>-1</factor>
-			<offset>1</offset>
+			<property>/sim/sound/external-custom</property>
+			<factor>1</factor>
 		</volume>
 		<orientation>
 			<x>-1</x>
@@ -423,9 +421,8 @@
 			</equals>
 		</condition>
 		<volume>
-			<property>/sim/sound/internal-custom</property>
-			<factor>-1</factor>
-			<offset>1</offset>
+			<property>/sim/sound/external-custom</property>
+			<factor>1</factor>
 		</volume>
 		<orientation>
 			<x>-1</x>
@@ -454,9 +451,8 @@
 			</equals>
 		</condition>
 		<volume>
-			<property>/sim/sound/internal-custom</property>
-			<factor>-1</factor>
-			<offset>1</offset>
+			<property>/sim/sound/external-custom</property>
+			<factor>1</factor>
 		</volume>
 		<orientation>
 			<x>-1</x>
@@ -485,9 +481,8 @@
 			</equals>
 		</condition>
 		<volume>
-			<property>/sim/sound/internal-custom</property>
-			<factor>-1</factor>
-			<offset>1</offset>
+			<property>/sim/sound/external-custom</property>
+			<factor>1</factor>
 		</volume>
 		<reference-dist>30</reference-dist>
 		<position>
@@ -508,9 +503,8 @@
 			</equals>
 		</condition>
 		<volume>
-			<property>/sim/sound/internal-custom</property>
-			<factor>-1</factor>
-			<offset>1</offset>
+			<property>/sim/sound/external-custom</property>
+			<factor>1</factor>
 		</volume>
 		<reference-dist>30</reference-dist>
 		<position>
@@ -531,9 +525,8 @@
 			</equals>
 		</condition>
 		<volume>
-			<property>/sim/sound/internal-custom</property>
-			<factor>-1</factor>
-			<offset>1</offset>
+			<property>/sim/sound/external-custom</property>
+			<factor>1</factor>
 		</volume>
 		<orientation>
 			<x>1</x>
@@ -562,9 +555,8 @@
 			</equals>
 		</condition>
 		<volume>
-			<property>/sim/sound/internal-custom</property>
-			<factor>-1</factor>
-			<offset>1</offset>
+			<property>/sim/sound/external-custom</property>
+			<factor>1</factor>
 		</volume>
 		<orientation>
 			<x>1</x>
diff --git a/Systems/a320-adr.xml b/Systems/a320-adr.xml
index 070643c7..9d3479fd 100644
--- a/Systems/a320-adr.xml
+++ b/Systems/a320-adr.xml
@@ -75,51 +75,19 @@
 		
 		<fcs_function name="/systems/navigation/probes/tat-1/compute-tat">
 			<function>
-				<difference>
-					<product>
-						<sum>
-							<property>/environment/temperature-degc</property> <!-- SAT -->
-							<value>273.15</value>
-						</sum>
-						<sum>
-							<value>1</value>
-							<product>
-								<value>0.2</value> <!-- ratio of specific heats - 1 / 2 -->
-								<value>0.995</value> <!-- empirical recovery factor -->
-								<pow>
-									<property>velocities/mach</property> <!-- going to use the pure value of mach here and then calculate another value -->
-									<value>2</value>
-								</pow>
-							</product>
-						</sum>
-					</product>
-					<value>273.15</value>
-				</difference>
+				<product>
+					<value>0.995</value> <!-- empirical recovery factor -->
+					<property>propulsion/tat-c</property>
+				</product>
 			</function>
 		</fcs_function>
 		
 		<fcs_function name="/systems/navigation/probes/tat-2/compute-tat">
 			<function>
-				<difference>
-					<product>
-						<sum>
-							<property>/environment/temperature-degc</property> <!-- SAT -->
-							<value>273.15</value>
-						</sum>
-						<sum>
-							<value>1</value>
-							<product>
-								<value>0.2</value> <!-- ratio of specific heats - 1 / 2 -->
-								<value>0.996</value> <!-- empirical recovery factor -->
-								<pow>
-									<property>velocities/mach</property> <!-- going to use the pure value of mach here and then calculate another value -->
-									<value>2</value>
-								</pow>
-							</product>
-						</sum>
-					</product>
-					<value>273.15</value>
-				</difference>
+				<product>
+					<value>0.996</value> <!-- empirical recovery factor -->
+					<property>propulsion/tat-c</property>
+				</product>
 			</function>
 		</fcs_function>
 		
diff --git a/Systems/sound-common.xml b/Systems/sound-common.xml
index 2f8985b0..eabc0903 100644
--- a/Systems/sound-common.xml
+++ b/Systems/sound-common.xml
@@ -55,6 +55,18 @@
 		<output>/sim/sound/internal-custom</output>
 	</logic>
 	
+	<logic>
+		<input>
+			<not>
+				<equals>
+					<property>/sim/sound/internal-custom</property>
+					<value>1</value>
+				</equals>
+			</not>
+		</input>
+		<output>/sim/sound/external-custom</output>
+	</logic>
+	
 	<!-- Misc -->
 	<filter>
 		<type>gain</type>