Ours is much much louder than anything in our lab, significantly outpacing a pair of Siglent SDS2104X+ which many consider to be on the fan loud side, and our Tonghui TH2830 sounds like a whisper compared to the Hioki!!
We did contact Hioki and they were responsive, and compared a video we sent to a IM3536 in their lab in Texas. The result was that one in the Hioki lab produced a similar fan noise.
Best,