Audio: retrograde (0:08)
retrograde plays a retrograde and offset variant of elision and ellipsis on an English horn. The retrograde figure shows the score. Only the retrograde and offset variant in the bottom part is played, the retrograde variant in the top part is there solely for comparison.
A retrograde melody is a reverse melody.
Reversing a melody significantly changes its rhythm. It is a more radical technique than invert melody, which always preserves the rhythm of the original. You may, of course, strike lucky and achieve the effect you want first time round, more likely, the rhythm of the reverse variant will be startlingly different.
This is the case with retrograde. The solution is more tweaking.
The unaltered reverse melody, shown in the top part of the score, has an unbelievable rhythm. It is a syncopated rhythm in 4/4 meter yet it looks a challenge to sing or play. The solution is shown in the bottom part of the score and it is a simple one: offset the melody backwards by half a bar. The rhythm is still syncopated but now it is possible to at least tap your foot to it.
It is of course entirely your choice whether to write a retrograde variant. The benefits are that the change in rhythm may be pleasing; there is plenty of scope for further variation using offset, elision, ellipsis and substitution; and a retrograde melody can be written for any musical instrument.
Whilst it is perfectly feasible for an instrumental melody to be written in reverse, a sung melody with lyrics cannot be written backwards. Well it can. But.