warrant officer a. p. kozhanov -lrb- explanatory report -rrb- : `` you could hear the ballast being blown , and we realized that the submarine had surfaced -lrb- we understood this from the depth gauge and from the rocking -rrb- , after that the whistling of air could be heard for some time longer , after which we could see from the pressure gauges that high-pressure air cofferdams 1 , 3 and 4 were completely discharged .