On an A-scan display, the 'dead zone' refers to which of the following?

• A. The distance contained within the near field
• B. The area outside the beam spread
• C. The distance covered by the front surface pulse width and recovery time
• D. The area between the near field and the far field

Answer: (C)

In an A-scan, the dead zone is the distance from the probe face that corresponds to the time the transducer is still ringing after sending the pulse and the receiver is not yet listening. The front surface pulse width and the recovery (ring-down) time set how long the transducer is effectively blind to echoes. The distance that sound travels during that time defines the dead zone, because any reflections originating within that interval cannot be resolved. In practical terms, you’re converting that listening time into a physical distance, using the material’s sound velocity, and that distance marks the near region where flaws cannot be detected. This concept is about the transducer’s timing and ringing, not about the beam’s geometric near-field or far-field regions.