It's can be daunting to think about, but we’re probably going to be finding easter eggs in Super Mario Odyssey for years to come. It was designed to pay attention to big spectacles as much as little details, and that’s a big part of what makes playing it a special experience.
The problem with little details is that even though they can subtly add to such an experience, they can also be incredibly easy to miss. They have their effect without a player ever even thinking about them. I’ve certainly never thought to compare the sound effects in one area to the sound effects in another, because my brain tells me they’re the same.
Except they’re not.
This is one of the game’s subtler tricks, but thanks to musician and streamer Joey Lopes it’s been demystified.
Lopes shared a short but illuminating video on YouTube about the way music and sound interact in Odyssey. In it, Lopes uses a conveniently placed power line that appears in Toastarena Town to demonstrate the way that sounds in the game can harmonize with the music playing in the background.
After capturing the power line and using it to move across a boundary where a music shift happens, the sound effect of traveling along that same power line audibly changes to match the new tune. In the comments, he notes that other items including rocket flowers respond similarly to the music. Lopes also transcribed these changes into musical notation for his video, which is very helpful for understanding those shifts if viewers happen to know a bit of music theory.
Regardless of how much musical prowess someone has, this remains a cool little trick. If nothing else, it makes me appreciate the profound care that went into making Odyssey even more than I already did.