Increasing the wall filter during Doppler sampling will most likely do what?

• A. Increase visibility of low velocity signals
• B. Increase spectral broadening
• C. Decrease bandwidth
• D. Reduce display of low-frequency shifts

Answer: (D)

The wall filter serves as a high-pass filter for Doppler signals, removing tissue motion and very slow flow. When you increase it, the cutoff is raised, so low-velocity signals are suppressed and fall off the display. That leads to a reduced display of low-frequency Doppler shifts, which is why this option is correct.

Increasing the wall filter would not increase visibility of low-velocity signals; it would suppress them. It doesn’t inherently increase spectral broadening—the range of velocities in a vessel—and the filter isn’t a measure of system bandwidth, so it doesn’t decrease bandwidth.