How far can a blue whales voice go?

There is no definite answer, but any answer applies to all sounds made underwater, whether by a blue whale or blue human. Low frequency sounds travel further. We know whales make low frequency sounds, like elephants, that we cannot hear, but they can.

Water temperature, salinity, and many other factors affect how far the whale can be heard. The question is poorly Worded in that sense.

Whale communication is also adversely affected by sonar pulses, boat noises and a lot of other noise humans cause and use.

I imagine the whale is saying, "What's to eat where you are?" or "I'm horny, anyone out there wanna have some fun?" And I wouldn't limit it to a "he" whale!