  Adding salt to water at ambient pressure affects its thermodynamic
properties. At low salt concentration, anomalies such as the density maximum
are shifted to lower temperature, while at large enough salt concentration they
cannot be observed any more. Here we investigate the effect of salt on an
anomaly recently observed in pure water at negative pressure: the existence of
a sound velocity minimum along isochores. We compare experiments and
simulations for an aqueous solution of sodium chloride with molality around
$1.2\,\mathrm{mol\,kg^{-1}}$, reaching pressures beyond $-100\,\mathrm{MPa}$.
We also discuss the origin of the minima in the sound velocity and emphasize
the importance of the relative position of the temperatures of sound velocity
and density anomalies.
