  The presence of flare related acoustic emission (sunquakes) in some flares
represents a severe challenge to our current understanding of flare energy
transport processes. We present a comparison of new spectral observations from
Hinode's EUV imaging Spectrometer (EIS) and the Interface Region Imaging
Spectrograph (IRIS) of the atmosphere above a sunquake, and compare them to the
spectra observed in a part of the flaring region with no acoustic signature.
Evidence for the sunquake is determined using both time-distance and acoustic
holography methods, and we find that, unlike many previous sunquake detections,
the signal is rather dispersed, but that the time-distance and 6 and 7 mHz
sources converge at the same spatial location. We also see some evidence for
different evolution at different frequencies, with an earlier peak at 7 mHz
than at 6 mHz. Using spectroscopic measurements we find that in this location
at the time of the 7 mHz peak the spectral emission is significantly more
intense, shows larger velocity shifts and substantially broader profiles than
in the location with no sunquake, and that there is a good correlation between
blue-shifted, hot coronal, hard X-ray (HXR) and red-shifted chromospheric
emission, consistent with the idea of a strong downward motion driven by rapid
heating by non-thermal electrons and the formation of chromospheric shocks.
Exploiting the diagnostic potential of the Mg II triplet lines, we also find
evidence for a single, large temperature increase deep in the atmosphere,
consistent with this scenario. The time of the 6 mHz and time-distance peak
signal coincides with a secondary peak in the energy release process, but in
this case we find no evidence of HXR emission in the quake location, but very
broad spectral lines, strongly shifted to the red, indicating the possible
presence of a significant flux of downward propagating Alfven waves.
