It is represented by larger sine waves going into the QC20 and smaller smoothed out sine waves coming out. I purchased this headset because of its amazing reviews. I am going to order another pair - probably in the same colour again as I like this shade so much. Excelente regalo. I am very happy with them Sound quality: Balanced and detailed, I could make out enemy steps over the gun fire, or the flute playing the background of percussion, relaxing and got the job done. So in respect for the author and their work, I am going to start pasting this along with a generic review I found somewhere. If you go direct to Birkenstock online, this sandal is listed as unisex. The volume is fantastic. I was surprised theyre cute theyre comfy thats a fact my toddler she just loves them.