Fun fact: the International Bureau of Weights and Measures in Paris is the owner of a perfect 0 dB noise floor enclosed in a perfect titanium sphere (with some sheep's wool filling to avoid reflections). There is a small door on the side over which microphone capsules can be inserted for calibration.
I genuinely wish there was a cost estimation feature built into them. Doesn't even have to be even remotely close to the true cost if it's anything like the meetings I attend, there will be enough people and it will go on for long enough to make up for it.
I worked as consultant. And started billing at normal hourly rates for meetings. You will be surprised how fast the company desire for my participation in them decreased.