This edition comes with no CD. You must purchase either the associated CD separately or digitally download the CD from an on-line vendor. Otherwise this book is exactly the same as the book/CD edition. KEY NOTE RECOGNITION is part of a series of ear training books designed to help the student develop better relative pitch. This book and separately available CD addresses hearing one specific note against all keys, allowing the student to identify key modulations when they occur. Recommended for use prior to "Ear Training Two Note Method".Recommended prerequisite to this book: "Ear Training One Note Complete." As mentioned the audio portion of this book is also available in CD and MP3 format. This CD and MP3 audio has the same title as this book. Both formats can be purchased from various on-line vendors. A list of recommended vendors can be found on the muse-eek.com website. This book is a required text for students at New York University and Princeton University and is recommended for beginning through advanced students ages 13 and up.