As imaging depth increases transmit time remains _______ while listening time is ______.

As imaging depth increases transmit time remains _______ while listening time is ______.

• A. Constant; Shortened
• B. Variable; Prolonged
• C. Constant; Prolonged
• D. Prolonged; Constant

Answer: (C)

The main idea is that the transmitted pulse has a fixed duration, set by the transmitter and transducer, so transmit time stays the same regardless of depth. In contrast, as imaging depth increases, echoes have to travel farther to and from the target, so the window during which the system listens for echoes—the listening time—gets longer. In tissue, echo return times increase roughly in proportion to depth, so the receive window is prolonged. For these reasons, the correct statement is that transmit time is constant while listening time is prolonged.

The main idea is that the transmitted pulse has a fixed duration, set by the transmitter and transducer, so transmit time stays the same regardless of depth. In contrast, as imaging depth increases, echoes have to travel farther to and from the target, so the window during which the system listens for echoes—the listening time—gets longer. In tissue, echo return times increase roughly in proportion to depth, so the receive window is prolonged. For these reasons, the correct statement is that transmit time is constant while listening time is prolonged.