This piece focuses the augmentation of an existing instrument. It requires a piano, a PA system, microphones, a MIDI pedal, and a computer running the reversing pedal software. I like to think of the combination of the MIDI pedal, the computer and the software as a single unit that is from now on referred to as a reversing pedal. Conceptually, the reversing effect is similar to an echo. If Hera had cursed Echo to only repeat backwards what others had said, this is what you might get. (footnote) An audible echo can be likened to a reflection such as the reflection that Narcissus sees in the pool. These could be referred to as spatial reflections since in each case a sound or image travels to a reflecting surface and back to the subject. The reversing pedal causes what I would like to call a temporal reflection, reflecting back in time rather than space.
When the pedal is pushed and until it is released, the sound leading up to the moment it was pressed is played back in reverse as though a hypothetical back button was suddenly pressed on a tape player. The reversed sound is in fact analagous to a second tape playback head that moves into the past while simultaneously recording into the present. When the pedal is lifted the tape head returns to the present and waits until the pedal is again pressed before moving once again back into the past but feeding back into the present. The piece employs this feedback process to build up layers of harmony, and by holding the reversing pedal for a longer time, removes them. This is similar in some respects to a looping delay module but with certain differences. The pedal with which the reversing algorithm is controlled is nothing more than a single switch, which makes it very simple to operate. By the addition of the reversing pedal, the piano loses nothing but gains many new possibilities.
The concept of the reversing pedal is implemented using a computer using my prreverse algorithm. The incoming audio is recorded into a circular memory buffer and when the reversing pedal is depressed it is played back from the present moment, in reverse, until the pedal is lifted. The output of the reversing process is routed to the speakers and also incorporated with the incoming audio and fed back into the rotating buffer.
The prelude is based on the rules of traditional harmony and counterpoint and while it doesn't follow them strictly it stays within the vocabulary of modern tonal harmony. I hope that this will make it a good introduction to the reversing pedal for traditional musicians so that composers might be inspired to compose using it or so that performers can prepare for more difficult repertoire.
At the start of the piece, the pedal is changed (lifted and immediately pressed again) on every note building up layers of alternating chords until bar 4 where it is held for two bars, allowing the layers to gradually peel away again while new notes are added underneath. When the pedal is changed again in bar 6 it is held for almost twice as long - for three and a half bars until bar 9, at which point it is held for about twice as long again. In this pattern, the piece repeatedly returns to the beginning replaying the piece so far, each time doubling its length and adding another musical layer.
The following sections use the pedal more as an an effect than as a structural device. In bar 18, it is used to reverse the first three quarters of the first C and so extend its length by a crotchet to form a suspension against the D. A pleasant side effect of this device is that the dissonant note crescendos, something the piano cannot do normally but something that a string or wind player or a singer probably would. In bar 19 the pedal is held long enough to return to the suspension of C against D where it becomes the tonic and seventh note in a dominant seventh third inversion leading to G. This helps to demonstrate the versatility of the reversing pedal.
The palindrome, as the name implies, sounds the same in reverse as forwards. While the palindrome is not a new concept (footnote), traditional examples involve the retrograde inversion of notes. Modern music technology allows sound to be recorded and played backwards so a more literal approach can be taken. This palindrome, rather than simply inverting the notes, also inverts the sound of the palindrome. I will refer to this as a sonic palindrome.
I have written a number of peices that are sonic palindromes in the past. The first was made as a proof of concept and was constructed by arranging the forward musical elements, recording the composition to disk, reversing it, then superimposing the reversed version on the original. This construction is equivalent to that of the crab canon where 'the original is present with the retrograde' [Newbould]. The forward elements were arranged carefully so that they would work with the reversed ones. I then began working on a palindrome that could be played live. The approach I took was to record live musical input into a buffer and programmed a sequence that would play back parts of the buffer forwards and backwards into a second buffer. At the midpoint of the piece, the second buffer was played back in reverse to give the palindromic structure. Because about half the material in the first half was reversed, the second half of the piece doesn't sound suddenly backwards. This approach helped me with my next palindromic studio piece, 'What it Feels Like to Be a Lamp Post' where I started from the middle of the piece, building outwards adding the same thing to the beggining as I added in reverse to the end.
In the live palindrome described above, it was necessary to play along to a metronome click in order to synchronise with the programmed sequence and to play exactly in the temporal windows specified by the same, while changing the structure of the composition meant editing the sequence. These problems are in part what led me to design the reverser - as a way to realise an interesting, multi layered palindromic piece without the need for a predetermined sequence or metronome and to put the musician in control of the reversing process.
The piece is built up from palindromic units. When the main palindromic theme is first played, the reversing pedal is pressed at its midpoint so the second half overlaps with the revrse of the first. The first approach I tried was to press the pedal at the same time as playing the middle note with the result that the tail of the forward notes overlap with the reversed tail of the reversed notes as illustrated in the 'reversing pedal pressed on the beat' example in the adjacent diagram. This was unsatisfactory since the pitches of the forward and backward notes clashed. I found that a solution to this problem was to press the pedal between beats so that the tails of the reversed notes overlap the tail of the same forward note as shown in the 'reversing pedal pressed between the beat' example.
At the midpoint, the reversing pedal is held down and the whole piece played back in reverse.