  In this short note, we study the variation of orbital integrals, as traces on
the group algebra $G$, under the deformation groupoid. We show that orbital
integrals are continuous under the deformation. And we prove that the pairing
between orbital integrals and $K$-theory element of $C^*_r(G)$ stays constant
with respect to the deformation for regular group elements, but vary at
singular elements.
