Originally posted by CrashTest:
In my Henle edition of the Mozart sonatas, they say that the "long" appogiatura becomes a suspension (I think they mean it changes with the note is precedes), does this only occur when the appogiatura is above the note? When it is below, look in measure 7 of sonata k.330, does that appogiatura get played on the beat, or before?
Also, it says ornaments are played on the beat. I understand trills and the like to be on the beat, but what about appogiaturas[/b]
I guess it's time for the annual appoggiatura festival.
In the case of Mozart (and most other music written for nearly another hundred years afterwards), you have to think of an appoggiatura as just another ornament. As your Henle edition states, all ornaments are to be played on the beat (or perhaps more clearly, at the time that following normal-size note would be played).
There are long and short appoggiaturas. The long appogiatura takes half (sometimes more in really slow tempi) of the next note's value. A long appoggiatura is written without a slash through the stem. The short appoggiatura, written with a slash through the stem, is extremely short, usually less than one-fourth the value of the following note.
Appoggiaturas should not be confused with "grace notes" which only really start to appear about the time of Chopin and Schumann. These are notated in similar fashion to the appoggiatura, but are almost always placed in the score so that they are clearly intended as such (when at the start of a measure, for example, they are usually written at the end of the previous measure). There are no grace notes in Mozart.
As for the comment about an appoggiatura becoming a suspension, I believe the indication is that when the written appoggiatura is the same note as the previous note, the appoggiatura should be 'tied' to the previous note and treated like a suspension and not sounded separately.
Hope that clears a few things up. If anyone disagrees with these statements, please feel free to comment. I can't make any claim to be authoritative.