It's always bothered me that this new Russian Stealth sub that supposedly had the capability to sneak up on the US coastline loaded with nuclear missiles, was easily detected by the sonar man on the Dallas.
Whales humping & farting? Really? Seismic anomaly? Seems like a pretty big flaw in the submarine design. And if it is that easily trackable, the whole premise of defection is unnecessary.
Jones was much better at his job than most sonar-men. He had to analyze the faint sound he heard using his own crude methods, and after speeding up the recording realized it had to be man made. The only reason he was able to do that is because they were lucky enough to catch the Red October leaving port and were already tracking it when it went silent. Had it approached them running the caterpillar drive Jones probably never would have even heard it, and if he had heard, it would sound nothing like a sub so would be unlikely to have recorded or analyzed it on his own.
It was a talented sonar man combined with luck.