13. The computer-readable medium of claim 1 , wherein the instruction for characterizing the melody of the musical query, comprises instructions for: assigning a digital representation of the number zero to the first note of the sequence; and for each note of the sequence after the first note, assigning a digital representation of an integer number signifying the pitch difference of the note under consideration with respect to the first note.
13. The computer-readable medium of claim 1 , wherein the instruction for characterizing the melody of the musical query, comprises instructions for: assigning a digital representation of the number zero to the first note of the sequence; and for each note of the sequence after the first note, assigning a digital representation of an integer number signifying the pitch difference of the note under consideration with respect to the first note. 14. The computer-readable medium of claim 13 , wherein the instruction for assigning a digital representation of an integer number signifying the pitch difference of the note under consideration with respect to the first note for each note of the sequence after the first note, comprises instructions for: computing the difference in pitch between the note under consideration and the first note in terms of the number of semi-tones separating said notes; assigning a digital representation of an integer number equal to the number of semi-tones separating the note under consideration and the first note of the sequence, wherein the integer number is positive whenever the note under consideration has a higher pitch than the first note, the integer number is negative whenever the note under consideration has a lower pitch than the first note, and the integer number is zero whenever the note under consideration has the same pitch as the first note.