fgdata/Aircraft/ufo/ufo-sound.xml

<?xml version="1.0"?>
 
<PropertyList>

 <fx>
 
<!--
  <engine>
   <name>rumble</name>
   <mode>looped</mode>
   <path>Sounds/rumble.wav</path>
   <property>/velocities/airspeed-kt</property>
   <volume>
    <property>/velocities/airspeed-kt</property>
    <factor>0.0001</factor>
    <min>0.0</min>
    <max>0.0</max>
   </volume>
   <pitch>
    <property>/velocities/airspeed-kt</property>
    <factor>0.0001</factor>
    <offset>1.5</offset>
   </pitch>
  </engine>
-->

  <machwave>
   <name>Shock Wave</name>
   <path>Sounds/exhaust_loop.wav</path>
   <mode>looped</mode>
   <property>/sim/sound/machwave/active</property>
   <volume>
    <expression>
     <table>
      <property>/sim/sound/machwave/offset-m</property>
      <entry>
       <ind>15</ind>
       <dep>1.0</dep>
      </entry>
      <entry>
       <ind>20</ind>
       <dep>1.0</dep>
      </entry>
      <entry>
       <ind>30</ind>
       <dep>1.0</dep>
      </entry>
      <entry>
       <ind>75</ind>
       <dep>0.0</dep>
      </entry>
     </table>
    </expression>
   </volume>
   <pitch>
    <expression>
     <table>
      <property>sim/sound/machwave/offset-m</property>
      <entry>
       <ind>15</ind>
       <dep>2.5</dep>
      </entry>
      <entry>
       <ind>20</ind>
       <dep>2.5</dep>
      </entry>
      <entry>
       <ind>30</ind>
       <dep>2.5</dep>
      </entry>
      <entry>
       <ind>75</ind>
       <dep>1.5</dep>
      </entry>
     </table>
    </expression>
   </pitch>
  </machwave>

 </fx>
 
</PropertyList>