A bat kol, lit. a 'daughter of a voice', is understood by Marcus Jastrow as a divine voice, a substitute for prophecy. The instance of a bat kol occurs many times in the Talmud1. There are sources that clearly indicate when prophecy ended, and these sources identify the bat kol as a replacement of sorts.
How was the experience of a bat kol different from that of actual prophecy?
From the sources I've seen, they seem to be short experiences and their name, which is also understood as an echo or a reverberating sound by Jastrow, indicates that they may have been unclear and hard to make out. Do any sources or commentaries discuss the differences?
Sources preferred, but any well-reasoned ideas welcome.