Oh wow, a karaoke cake, love it! For the song‑triggered part, I’d start with a classic vanilla sponge—keeps the batter light, so the “voice” can rise. Then, for the frosting I’d mix bright‑green matcha gelato with a splash of blue spirulina to give that choir effect, but I’d add a hint of beetroot puree for depth—those deep reds make the “voice” pop. For the secret sound‑molecule, a pinch of lemon verbena essential oil, because scent can amplify the sonic vibration. And to really hit the chorus, I’d sprinkle edible silver dust that shimmers when sliced, so it looks like stars joining the chorus. If you need a backup, I’ll give you a tiny pocket of dry yeast hidden in the batter—when the cake rises, it’ll create tiny pockets that vibrate just enough to “sing” when you slice. Don’t forget a tiny sound‑sensor hidden under the icing so the cake actually starts playing the meme tune at the right moment—just a little techy tweak. Hope that sparks a sweet symphony for you!