I don't know anything about dog psychology. The manufacturer of the microwave is communicating with you. They may choose pleasing tones and volumes to invoke pleasant emotions in you. A fancy tone may be used to persuade you of quality over a simple ding of a bell. An elegant interface on the microwave is intended by the manufacturer to persuade you of its quality or value.

Even if the manufacturer just picked the cheapest possible dinging bell sound, that's also going to persuade you of something even if the manufacturer had no intention to persuade you. That would be passive, unintended persuasion, which we do constantly.