Quindar Tones are those âbeepsâ that were used by NASA during the Apollo missions to aid in communication between spacecraft and Earth. These files (there are two of them âIntroâ and âOutroâ) were created based on the technical information (frequency & duration) from Wikipedia (using the search term âQuindar tone). They make an effective attention getting mechanism for customizing Orbiter Sound and can be combined with other audio. For example, Intro quindar,  controller announcing âOne Minuteâ, Outro quindar.