what is a musical gesture?
what does it share with / how does it differ from:

physical gestures of the hands/arms?

facial gestures?

see also Descriptors

There are several meanings attributed to the word gesture, even within the relatively limited context of music, and various interpretations of the significance of musical gesture.  The gesture may be interpreted, at perhaps its most basic, as the sonic result of a physical gesture on a sound-producing object, such as the strum of a guitar, the strike of a mallet on a xylophone, or the bowing of a cello string.  It is quite possible for those with a well-developed aural imagination to realize that the energy involved in such gestures is clearly transmitted by the resultant sound, and thus we may understand the association of gesture with its musical counterpart: we can aurally differentiate between an energetically-bowed chord and a meekly-bowed one (but is this universal, or the result of habituation?)

As Ferneyhough points out, gestures are traditionally indicators of meaning, and he deplores the usage of gestures in music which share the outward characteristics but have no musical meaning, or "expressiveness" (FFS, pp 33-34, ff).  Sullivan, in a similar vein, compares the examination of musical gesture without examining its function is like studying the pointing finger rather than that to which it is pointing.  However, there is another perspective which finds the study of gesture interesting in itself, as revealing more or less of its original intent or signification:  the dancer who bows low may or may not be referring to a subservience to something / someone else, but in any case the bow can be identified as more or less energetic, smooth, casual, etc.  Similarly, the musical gesture can probably be used to convey degrees of energy, character, etc. without further analysis of function (from which it may, in fact, be divorced, beyond abstract musical functions of texture and energy profile shaping.

The term "gesture" is also sometimes used in musical contexts in an analogous way, such as referrals to the opening gesture of a work.  In this case, the function is similar to a physical gesture, in that a general, often formalized, pattern is used to suggest a familiar action.

Denis Smalley speaks of the "energy trajectory" of a gesture. My impression of a gesture is that in a "normal" state, it will be short, probably framed by silence, and imply a continuity of movement -- just like a typical physical gesture of the hands/arms.  It also, to me, suggests a lack of repetition: once there is repetition, it is a repeated gesture (implying that a non-repeated kernel gesture could be isolated from the repeated series).  The implication of movement can also be understood as the (single) action resulting from a single energy burst.  This unity of movement may be conveyed by the linear or logarithmic organization of one or more of the parameters: thus, an ascending line of pitches; a steady crescendo  / decrescendo pattern of amplitude; a series of increasingly long durations; etc.

For a while, I examined gestures with the help of a group of dance students at the University of Concordia and their professor Silvy Panet-Raymond.  This is now part of the IMP-NESTAR project.  There are various results so far:

(1)  the exchange of perspectives and ideas is fruitful in clarifying what we (each) mean by "gesture", and to what extent our views and terminology are compatible;

(2)  if, as I suspect, the idea of musical gestures originally had its basis in the physical gesture, either through the direct correlation of a gesture on an instrument with the resulting sound, or through the sonic imitation of a physical gesture, then such a study is likely to shed light on our understanding of musical gesture;

(3) by examining the way in which dancers can differentiate various manifestations of a single gesture, composers can receive not only a general stimulus, but also try to establish how to transfer the manner of variation from one medium to another.