Maps of travel-time shifts obtained for the sunspot model with B_u = 1500 G and z_WD = 550 km using phase speed and frequency bandpass filters. Each column corresponds to a different phase-speed filter (the name of the filter and its phase speed in km s^-1 are indicated at the top). The rows correspond to frequency filters (increasing from 2.75 mHz in the top row to 5.25 mHz in the bottom row).