The Hunt for Red October (Jack Ryan, #3)

by Tom Clancy

An eyebrow went up, and his nearly bald head cocked to one side. The pulls on the pipe grew irregular. His right hand reached forward to the control panel and switched off the signal processors so that he could get the sound without computerized interference. But it was no good. There was too much background noise. He switched the filters back on. Next he tried some changes in his azimuth controls. The SOSUS sensors were designed to give bearing checks through the selective use of individual receptors, which he could manipulate electronically, first getting one bearing, then using a neighboring gang to triangulate for a fix. The contact was very faint, but not too far from the line, he judged. Franklin queried his computer terminal. The USS Dallas was up there. Gotcha! he said with a thin smile. Another noise came through, a low-frequency rumble that only lasted a few seconds before fading out. Not all that quiet, though. Why hadn’t he heard it before switching the reception azimuth? He set his pipe down and began making adjustments on his control board.