Opening
Introductory movement or section.
What it means
Opening (German Eröffnung) designates the introductory movement or section of a work — that piece of music which sets the beginning and creates the frame for what follows. The term is more general than overture, prelude, or praeludium and includes these as particular forms. What can be meant is an independent movement before a stage work, a slow introduction before a fast movement, or the first section within a movement in which the material is presented.
Musical use
Openings fulfil several tasks at once: they establish key, tempo, and character, gather attention, and prepare musically what follows. Some anticipate thematic material, others deliberately set a contrast. Historically, fixed types have formed — the French overture with a dotted slow introduction and a following fugal part, the Italian sinfonia in three sections, the free prelude. Even in works without an opening movement of their own, the beginning is formally distinguished: the first bars shape the listener's expectation more strongly than any later passage.
An opening can be an independent movement, for instance an overture, intrada, sinfonia, or prelude, or the initial part of a larger movement. It presents key, character, and scoring and prepares the audience for what follows. In opera the opening attunes to the action, in suites to the dance character. In concerts it used to be usual to begin with an overture that gathered attention.
Performance practice
Prepare the beginning with particular care: tempo, character, and tone colour must be there from the first note; finding one's feet during the first bars is audible. Settle in the ensemble how the entry is given, and breathe together. Take care not to begin too massively so that possibilities of intensification remain. With slow introductions, plan the relation to the following fast part, because the two work together. Check the effect in the room, because beginnings react particularly sensitively to acoustics.
Bear in mind that a beginning should also be checked acoustically: what begins clearly in the rehearsal room can blur or seem too hard in the hall. Try out the entry in the performance space and adapt tempo and articulation.