This function makes it more comfortable and convenient for you to hear ambient sound (such as aeroplane announcements or make conversations when you shop), without the need to remove your headphones or lower the volume of the music you're playing, phone calls, and ringtones. To activate this function, cover the entire touch sensor control panel with your hand. You can also check the detailed instructions in the following video. (The video uses WH-1000XM3 as an example.)