It's not. You should actually try out the exercise. (I used this approach to build partial perfect pitch, i.e., to sing/identify a small number of specific pitc

It's not. You should actually try out the exercise. (I used this approach to build partial perfect pitch, i.e., to sing/identify a small number of specific pitches.) Close your eyes and try to imagine a song that you know really well. Imagine the original version playing on your phone/mp3 player/cd/record. Pick a stable note from that song (for me, the third note of the beginning of "Tears in Heaven" is a solid A.) Try to sing it and match the pitch in your head. As you practice it you'll get better, and do it faster, and over time even be able to recognize it in the wild.