Checking the Frequency Response Bandwidth makes sure you have set the range of measurement large enough to capture all the data, but not too large to affect its accuracy. After completing your first X-Direction taps, click on the radio button next to Freq. Response.
Step 1: Cutoff Wave
Here is an example of a measurement where one of the mode waves is cutoff a 5000 Hz. The Bandwidth for this tool needs to be increased to 10,000 Hz, the tool re-practiced and re-tapped.