First off this question seems a little out of line with the site, not sure, but I think it's still a design question.
When I turn on the toaster oven, especially on a high setting, the compressor in the fridge next to it (presumably plugged into the same outlet) changes tone and gets a little lower/quieter. I am wondering why this would happen, since presumably, both devices are connected in parallel, and therefore both of them drawing current at once shouldn't do anything unless the current exceeds the breaker rating, in which case they should both lose power.
What part of (Canadian) house wiring am I misunderstanding?
Edit: To be 100% clear, I neither wired the house, nor plugged in the appliances - I am assuming that they are on the same outlet since the fridge reacts noticeably to the toaster. Either way, the point of the question was to understand what part of standard mains wiring is most likely to make the voltage source behave in a nonideal way, which is why I'm considering it a design question not a home improvement question.