  Using a high cadence imaging spectropolarimetric observation of a sunspot and
its surroundings in magnetically sensitive (FeI 6173 A) and insensitive (FeI
7090 A) upper photospheric absorption lines, we map the instantaneous wave
phases and helioseismic travel times as a function of observation height and
inclination of magnetic field to the vertical. We confirm the magnetic
inclination angle dependent transmission of incident acoustic waves into upward
propagating waves, and derive (1) proof that helioseismic travel times receive
direction dependent contributions from such waves and hence cause errors in
conventional flow inferences, (2) evidences for acoustic wave sources beneath
the umbral photosphere, and (3) significant differences in travel times
measured from the chosen magnetically sensitive and insensitive spectral lines.
