Recently I came across a forum contribution, where the author Charles Link describes how to use the unitarity of the Fourier transform on $L^2(\RR)$ to compute the definite integral

\begin{equation}\label{eq:I}

I(t_0) \DEF \int_{-\infty}^{\infty}{\frac{\sin(\tau – t_0)}{(\tau – t_0)}\frac{\sin(\tau + t_0)}{(\tau + t_0)}\,d\tau},

\end{equation}

where $t_0 \in \RR$ is a constant. In the comments it is also argued that one may alternatively use contour integration. I liked the article, but wondered whether the symmetry of the problem would perhaps admit a simpler approach.