I would say that both sounds *and* animation should only be used when they
enhance the message or the information you want to convey. Some people just
love to use the typewriter sound as they animate the text to appear on the
screen one letter at a time. I detest that! I stop listening to the presenter,
don't see the text on the screen, and start looking for the door.
On the other hand, if the presentation topic is musical instruments and the
presenter wants to familiarize a room of first graders with what each one sounds
like, setting a picture of a guitar to glide in while the sound of a strumming
guitar is playing is very appropriate.
It's a judgment that only you can make based on your audience and your subject.
