Schillinger believed in the biological origin of melody. For example, the emotion of joy is an expansive physical gesture, fear usually makes us shrink away or contract. A melody must have a point of balance, a pitch which roots it. This is represented by the first parameter in the function. Schillinger represents this balance point as a horizontal line on a graph. A melody moving towards the line from above or below represents contraction, the diminution of energy. A melody moving away from the balance line is expanding and gaining energy. These melodic directions are called secondary axes to distinguish them from the balance line which is the primary axis.
Axis-plot allows you to specify the direction of the melody: a = away from the primary axis in the upwards direction. b = towards primary axis, downwards. c = towards axis, upwards. d = away from axis downwards.In addition we must say how far in pitch the melody moves from the primary axis. This is the second part of axis-plot.
(interference1 '(8 5))
=> (5 3 2 5 1 4 4 1 5 2 3 5)
(axis-plot 0 '(a b c d) '(5 3 2 5 1 4 4 1 5 2 3 5))
