advertising and the mass media
with increased trade and mass production of good it was logical that producers needed persuasive techniques so that people would buy the products of one company rather than those of its competitors.
the popularity of radio and then television provided a new use for the spoken word. one style of advertisements which we still have today focuses on a voice of authority-supposedly an expert like a doctor or a scientist-who tells us what to buy because he know it is good for us.
But with radio and TV. advertisers soon realised that they were speaking to us in our living rooms at home and many advertisement became less formal as sellers adopted a style which spoke directly to the listener or viewer in a friendly way.