  This work investigates anomalous transmission effects in periodic dissipative
media, which is identified as an acoustic analogue of the Borrmann effect. For
this, the scattering of acoustic waves on a set of equidistant resistive sheets
is considered. It is shown both theoretically and experimentally that at the
Bragg frequency of the system, the transmission coefficient is significantly
higher than at other frequencies. The optimal conditions are identified: one
needs a large number of sheets, which induce a very narrow peak, and the
resistive sheets must be very thin compared to the wavelength, which gives the
highest maximal transmission. Using the transfer matrix formalism, it is shown
that this effect occurs when the two eigenvalues of the transfer matrix
coalesce, i.e. at an exceptional point. Exploiting this algebraic condition, it
is possible to obtain similar anomalous transmission peaks in more general
periodic media. In particular, the system can be tuned to show a peak at an
arbitrary long wavelength.
