How loud are the fans on dual channel SMUs?

The 2604B is of primary interest, but other dual channel SMUs would be of interest too. Measuring in A-wieghted dB at 1 meter from the unit would be a good metric, but even qualitative information would be helpful since there aren't a lot of review videos of these SMUs showing them running without overdubbed audio.
I did look in the datasheet (for "fan", "dB", and "loud") but didn't find anything. It would be helpful if this parameter was included in the datasheet.

Hello Jeremy,
We don’t have an exact number for the sound noise, but we have noise with maximum load conditions under 80 dBA for 2604B. This is the safety requirement for sound level. We confirm that the instrument 2604B complied with the requirement. But we don’t have actual noise under 80 dBA in number.