There are some misunderstandings here.
Basically, imagine a rod in space that is the length of one lightyear (ehrm, LONG). If you push in one end, will the other end move accordingly after one year, because it takes the light that much time to travel there? Not at all, it will move after time that is a product of the speed of sound in that material, which is much slower. When you push a rod, you push one atom, which hits the other atom, which hits the other atom, and so forth. This does not happen instantly, but with microscopical delays. THIS is speed of sound. In air, the speed of sound is rather slow (341 m/s I think) because there's a distance between the particles. In higher elevations the speed is slower, because the particles need to travel even MORE of a distance.
The speed of sound in water can be found (in feet/second at least) by use of
4388 + 11,25(temperature °F) + (0.0182 x depth + salinity (in parts-per-thousand, which I think is close to 35))
If I am not commmpletely off, that speed should be about 1500 m/s. I'm not doing the maths, though.
Basically, as with a RADAR, this also means that the TARGET hears the ping before anyone else. The time from the ping being sent out by the attacker, till it hits the target, is X. The time from the ping being sent out till it is heard by the attacker, is 2X, because the sound wave travels double the distance. These mechanics are not like those of a bullet in air.
Now, the pulses... are just pulses. The pushing of atoms, the frequency being how often the atoms are pushed in a second (translating to hertz).
Active sonar does not automatically give you a bearing of the contact unless you can distinguish his shape (a long boat's silhouette points in two directions, you figure out which he is facing by). A user of active sonar can not expect to make NO use of other sensors, unless the target is stationary. However, then he'd have to KNOW the target is stationary - only two or more pings may determine that. In a submarine, the user would definitely need use of hydrophones (passive sonar) and any other data he might be able to find.
Note that I do not claim to know the mechanics behind HEARING the ping. I, as someone posted before, expect that the hull of the submarine might act as a converter of sorts.