Introduced in TC-Helicons VoiceLive Play and VoiceLive Play GTX, 2 small microphones listen to music being created in the room and attempt to pick out chord information for use in processing Key/Scale. The best location to place your device using RoomSense is close to a chord based instrument, like a piano or guitar. The more clearly RoomSense can hear the chords, the more accurate it will be. RoomSense can also be blended in with your headphone mix to allow you to hear room sounds. This is especially useful with In Ear Monitors or IEMs.