I don't know if it's something to do with my 3ds but when I use the megaphone, it just says "seems like it's getting feedback". I probably seem like an idiot trying to speak Beau's name in different tones and I checked the sound on the settings and it's just fine. Is this a problem or?
The megaphone isn't the most accurate tool. Sometimes, I'll call out the name of a certain villager, but another villager or Kapp'n would answer instead (or no one would answer). Just keep saying his name. Eventually, he'll answer if he's strolling around in town.
When I'm having trouble calling for a villager I try to keep my voice in one steady tone. I have to say it like a monotone robot or it doesn't work for me.