I think you might misunderstand how sonar scales in range and intensity. Think of water as being much less like perfectly-transparent air, and more like a light, but continuous fog. After a certain distance, increasing the intensity of sonar will only give you a marginal increase in range, since a certain portion of your signal will end up scattered back at your hydrophones. No matter how 'noisy' they are, there's really absolutely nothing a surface ship can do to ensure they can detect a deep and silent running submarine that really doesn't want to be detected. It's also much easier to design a submarine to mask its active sonar (reflective) signal. Typically, detecting a submarine is more about having better 'eyes' than it does having brighter 'lights'.