The voice of a writer, an artist, a singer, a director, or a storyteller naturally changes over the course of their career, because, like every muscle that anyone uses regularly, the more that someone uses their gift of experience and imagination the more that they are able to act, to articulate, to show, or to say something without even having to think that much about it - because over time some things become effortless and as a result are able to grow and to morph into a state of being able to reform into any vision or personification of anything or anyone imaginable... the voice of people slowly but surely gets deeper as they grow older... the voice of people mostly gets wiser as they mature... the voice of a person's internal dialogue with themselves can get more insightful when attempting to answer life-long questions of meaning, reason, and choice... the way that people communicate with one another has been evolving since our ancestors used to spend their time sitting around a fire while sharing their beliefs and opinions about what they saw above them when they looked up at the night sky, as well as wondering what or who created them and everything - so it should be of no surprise for anyone that everybody over the course of their life will experience what it is like to hear their own voice changing.
