I guess it's highly likely JMSDF's helicopter dropped explosive sound sources very short distance to 093B.That data is also collected. In fact, the helo's sonar is just as or more important. Once you get the wave form, you can put that through a simulator against different water types based on temperature and salinity to determine its range and depth under varying conditions. The submarine can collect all that, and so can the Type 054A frigate nearby.