The sudden ones — sf, fp, subito · From Zero to Mozart

Not every dynamic changes gradually. Some marks hit a single note, and some flip the level in an instant with no ramp at all.

The marks

Mark	Name	What it does
sf, sfz, fz	sforzando / forzando	a sharp, forced push on that one note — then back to the prevailing level
rf, rfz	rinforzando	a reinforcement across a short group or until the next dynamic — broader than sf
fp	forte-piano	attack the note loud, drop to soft immediately, on the same note
sfp	sforzando-piano	a forced attack, then instantly soft
subito p / subito f	suddenly	the new level starts now, with no crescendo or diminuendo leading in

Hear it — forte-piano

72 bpm

The held B is marked fp: strike it with full weight and speed, then — almost at once — release to a whisper and let it sit there for the rest of the note. One note, two dynamics.

A forced note in a line — sfz

84 bpm

The whole line is p. The sfz jabs the high E — a sudden bite — then the very next note is back to soft. An sfz inside a quiet passage is a quiet jab: sharp, but scaled to its surroundings.

Suddenly soft — subito p

88 bpm

Loud for a full bar, then subito p — drop straight to soft with no fade. The surprise is the point; a diminuendo into it would spoil it. A Classical favourite.

Try it

Try

On the open A string, play one bow that is forte-piano: a fast, full start — the first centimetre of bow moving quickly with weight — then release almost immediately to slow, light travel and hold that soft sound to the end of the bow. The ear should hear "bam … hmmm."

The usual mistake

Playing sf as "loud from here on." It marks one note — the note after it returns to whatever level you were at. Second: forgetting the p in fp — the loud attack is easy to remember, the instant drop is the hard, characterful part. Third: confusing sf with a plain accent >. An accent leans on the note within the current dynamic; sf is the more violent gesture — a jab, not a lean — but both are still measured against what's around them.