Using Lusztig's geometric classification, we find the reducibility points of a standard module for the affine Hecke algebra, in the case when the inducing data is generic.This recovers the known result of Mui and Shahidi for representations of split p -adic groups with Iwahori-spherical Whittaker vectors.We also give a necessary (but insufficient) condition for reducibility in the nongeneric case.
Barbasch et al. (Sat,) studied this question.