  We are interested in the inverse problem of the determination of the
potential $p(x), x\in\Omega\subset\mathbb{R}^n$ from the measurement of the
normal derivative $\partial_\nu u$ on a suitable part $\Gamma_0$ of the
boundary of $\Omega$, where $u$ is the solution of the wave equation
$\partial_{tt}u(x,t)-\Delta u(x,t)+p(x)u(x,t)=0$ set in $\Omega\times(0,T)$ and
given Dirichlet boundary data. More precisely, we will prove local uniqueness
and stability for this inverse problem and the main tool will be a global
Carleman estimate, result also interesting by itself.
