  It has been shown that there is a potential ambiguity in the asteroseismic
determination of the location of internal structures in a pulsating star. We
show how, in the case of high-order non-radial acoustic modes, it is possible
to remove this ambiguity by considering modes of different degree. To support
our conclusions we have investigated the seismic signatures of sharp density
variations in the structure of quasi-homogeneous models.
