  This paper proposes a new research direction for the large family of
instrumental musical interfaces where sound is generated using digital granular
synthesis, and where interaction and control involve the (fine) operation of
stiff, flat contact surfaces. First, within a historical context, a general
absence of, and clear need for, tangible output that is dynamically
instantiated by the grain-generating process itself is identified. Second, to
fill this gap, a concrete general approach is proposed based on the careful
construction of non-vibratory and vibratory force pulses, in a one-to-one
relationship with sonic grains. An informal pilot psychophysics experiment
initiating the approach was conducted, which took into account the two main
cases for applying forces to the human skin: perpendicular, and lateral.
Initial results indicate that the force pulse approach can enable perceivably
multidimensional, tangible display of the ongoing grain-generating process.
Moreover, it was found that this can be made to meaningfully happen (in real
time) in the same timescale of basic sonic grain generation. This is not a
trivial property, and provides an important and positive fundament for further
developing this type of enhanced display. It also leads to the exciting
prospect of making arbitrary sonic grains actual physical manipulanda.
