Achange in tone is often used to listeners

Its often used to amuse or attract the attention of listeners.

Anxiety, stress, or something like that

Ok, before buying a burger. think of you diet and calories. how many calories are you suppose to eat a day. and look at how much fat, calories, salt is in it. if it is ok to you, then buy it. but if you think that it's to much fat and salt for you. don't buy !