The technology is simply completely different from that of a conventional cooktop or ceramic hob. With induction, the control electronics must be cooled, and every manufacturer solves this, depending on the price segment, somewhat differently; therefore, it is louder with one and almost inaudible with another. And I say, hearing is different for everyone, so the volume is also perceived differently by each individual.
Ich glaube, ich hole mir eine ganz normale Doppel-Kochplatte und gut ist...
You write, if I understood correctly, that you only need the hob occasionally as an addition. If so, I would think carefully about buying a conventional hob. True, the fans are somewhat louder, but for occasional use I think it's bearable.