What Makes a Voice Instantly Recognizable Even When You Can't See the Person?

Some voices are so distinctive that you can recognize the person within seconds, even if you aren't looking at the screen. Sometimes it's the tone, pitch, accent, rhythm, or the way they pronounce certain words. Other times, it's simply a unique quality in their voice that is difficult to describe. What do you think makes a voice instantly recognizable, and whose voice can you identify almost immediately?