  We study the quasi-normal modes of a massless scalar field in a general
sub-extreme Kerr back- ground by exploiting the hidden SL(2, R) x SL(2, R) x
SO(3) symmetry of the subtracted geometry approximation. This faithfully models
the near horizon geometry but locates the black hole in a confining
asymptotically conical box analogous to the anti-de-Sitter backgrounds used in
string the- ory. There are just two series of modes, given in terms of
hypergeometric functions and spherical harmonics, reminiscent of the
left-moving and right-moving degrees in string theory: one is over- damped, the
other is underdamped and exhibits rotational splitting. The remarkably simple
exact formulae for the complex frequencies would in principle allow the
determination of the mass and angular momentum from observations of a black
hole. No black hole bomb is possible because the Killing field which co-rotates
with the horizon is everywhere timelike outside the black hole.
