  For convex co-compact hyperbolic quotients $X=\Gamma\backslash\hh^{n+1}$, we
analyze the long-time asymptotic of the solution of the wave equation $u(t)$
with smooth compactly supported initial data $f=(f_0,f_1)$. We show that, if
the Hausdorff dimension $\delta$ of the limit set is less than $n/2$, then
$u(t) = C_\delta(f) e^{(\delta-\ndemi)t} / \Gamma(\delta-n/2+1) +
e^{(\delta-\ndemi)t} R(t)$ where $C_{\delta}(f)\in C^\infty(X)$ and
$||R(t)||=\mc{O}(t^{-\infty})$. We explain, in terms of conformal theory of the
conformal infinity of $X$, the special cases $\delta\in n/2-\nn$ where the
leading asymptotic term vanishes. In a second part, we show for all $\eps>0$
the existence of an infinite number of resonances (and thus zeros of Selberg
zeta function) in the strip $\{-n\delta-\eps<\Re(\la)<\delta\}$. As a byproduct
we obtain a lower bound on the remainder $R(t)$ for generic initial data $f$.
