Upon hearing the report from Sonar Technician No.1, the duty officer looked at him intensely. The duty officer knew the standards of Sonar Technician No.1, and he knew that he wouldn't fail to distinguish whether or not the target was a whale. He grabbed a spare earphone and put it on his head. Sonar Technician No.2 also began to track the unusual sound.
The three of them were in deep concentration, and the already quiet sonar room became even more quiet––so quiet that even their breathing could be heard clearly. Based on their judgment, they would decide whether or not to report the abnormal contact to the captain.
Half a minute later.
The duty officer let out a breath of air. The alertness on his face gradually disappeared and he smiled. "Turns out that an old friend is back," he chuckled and said to himself.
Sonar Technician No.1 had barely ever heard him laugh while on duty, so when he did, he couldn't help but ask, "Sir?"