More melodies need at most a 2 octave range (especially in pop), which limits us to 24 choices for each melody note. (Actually less, if you factor in the const

More melodies need at most a 2 octave range (especially in pop), which limits us to 24 choices for each melody note. (Actually less, if you factor in the constrains of the specific key the tune is in, but let's be maximalist and get an upper bound). Now, a melody also comes with a rhythm / syncopation pattern, but let's just count simple 8th notes in our test case (one can consider a whole note as 8 consecutive "legato" 8th notes of the same pitch for our purposes). How many bars? 8 bars might be a good starting point (many pop verses are that, eg: http://en.wikipedia.org/wiki/Thirty-two-bar_form http://en.wikipedia.org/wiki/Thirty-two-bar_form ). So, that would gives us: 8 bars * 8 eights with 24 notes for each eight, which gives us roughly: (8*8)^24 different melodies. Which is like, a lot, man (think 40-figure range). In practice it could be from much less (considering key constraints which limits the notes you could use) to much more (considering higher than 2 octaves Zappa or avant-guard like melodies, durations shorter than 8ths, etc). Another major factor is the "melodic quality" of the melody, which is kinda subjective. 8 bars of 8th C notes, for example, wouldn't be that interesting, and many people would not even consider them a melody. Still that would leave billions of quality melodies in the millions of trillions of possible melodies.