"William F. Dishman" <[log in to unmask]> wrote:

>Rubato in the strictist sense refers to  piano practice, specifically
>Chopin.  It is a difficult concept for me to understand as it refers to
>the left hand playing its part in a different tempo than the right hand.

This is simply extravagantly incorrect.  I'd like to clear up this
and some other confusion about these two terms.  Rubato is Italian
for "robbed", and is used in the performing of any music (singing or
instrumental).  It suggests that time is stolen from certain beats and
given to others, but this is misleading, since there is not literal
transferral of time.  (I.e. if you slightly shorten one beat of a measure,
you need not precisely compensate another beat proportionally; that is
ridiculous notion).  A better explanation of rubato is rhythmic freedom
not precisely called for in the score, the manner of execution determined
entirely by the performer.  (It does not specifically refer to
desynchronization.)

Occasionally a score calls specifically for rubato but usually how and
when to employ it is solely at the discretion of the performer.  (Obviously
an indiscreet performer can mangle a piece with poorly judged rubato or
other distortions.)  One of the hallmarks of a great musician is being
convincing in the employment of rubato, regardless of to what extent
they use it.

Ad libitum, Latin, more or less "as you please" is used much more
frequently as a musical direction, and indicates that the passage should
be played freely.  Note that you can play in strict relatively normal
time and still play ad libitum, since the employment of varying degrees
of dynamics and timbres can satisfy the direction.

Rubato is a technique (like legato), ad libitum is a musical direction.

Michael Cooper