The reason why narrators in back to school ads often speak faster than normal is because; The ads are being paid for per second and they need to say as much as possible within that period.
Usually in ads(advertisements) via any audible media means particularly by video or audio is usually as short as possible. This is so that the information can be passed across as fast as possible to the potential targets.
Now, this concept of advert when applied to back to school ads is not any different as in this too, they also have to speak faster than normal so they can fit in lots of information over the given short period of time since they pay per amount of seconds for which the ad runs.
Read more about Narrators at; https://brainly.com/question/13845140
