Phrasing involves certain rhythmic fluctuation which takes place at structurally important elements of the piece. This fluctuation helps to emphasize the places which make up the form of the composition. While the usual playing and articulation help to achieve the hierarchy of the strong and weak beats in the measure, the phrasing is used to make subtle rhythmic inequalities. In other words, with the help of the phrasing the organist is able to achieve gentle riterdandos and accelerandos which are governed by certain compositional elements. Sometimes phrasing has much to do with articulation and taking a breath in a musical line.
Cadence is a certain harmonic or melodic curve which helps to complete the musical idea. Whenever you see a cadence, you can gently slow down to make it more prominent. Gradually resume the normal speed afterwards.
Rests are important for the phrasing as well. Quite often the composer will put a rest in a place where one particular voice or part has to take a breath. This is the sign for the subtle phrasing technique.
Very often caesuras are placed at the end of the phrase in order to show the necessity of taking a breath. Although the organ can play without breathing, if you emphasize those musically important places and articulate them, your musical lines will become much clearer.
After the long note there is a tendency to take a breath in a vocal composition. The same applies in organ music as well. Make a short rest after long notes to show the contour of the melody.
Repetition of Rhythmical Figures
If you see some repeated rhythmical figures in your organ piece, feel free to make more pronounced articulation at the end of each figure. This will be a natural way to make phrasing.
Beginnings and Endings of Melodic Line
Very often it is appropriate to make gentle rhythmical inequalities at the beginning and the end of the melodic line. Start slowly, speed up a little and finish slower. This is especially useful in Romantic organ music. It is helpful to imagine analogy with driving a car here. Similarly to the shape and performance of the melodic line, the car will start to move slowly, speed up and slow down at the stop.
If you apply subtle rhythmical phrasing and make articulation at structurally important points of the piece, your performance will become very natural. However, do not over do it, especially in the Baroque music. Although the Romantic compositions often require these rhythmical alterations, the early music must be played much more rhythmically and should emphasize meter, pulse, and alternation of strong and weak beats.
If you want more information on phrasing and other aspects of performance practice, I recommend Making Music on the Organ by Peter Hurford.
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