Why do we speak to ourselves mentally when we're thinking?

nice bit of introspection..we talk to ourselves,since when we are thinking ytically,we create mental images in our mind,as what will follow the next...but when we are thinking about something viusal(such as a food treat etc)then we bring out the feelings ociated with taste in our minds..then if we think about experiences,then we tend to recollect our feelings and emotions in that very instance and try to talk ourselves through...its all about listening to our inner voice..the soul,when we are in solitude and which we seldom communicate in d myriad of life's confusions..