[DanDan]

Y'all. Here's a quote from the Bruel and Kjaer primer on Measuring Sound. I am sure they won't mind. By the way, a booklet worth reading over and over again, IMHO.
"When measuring noise, precautions should be taken to
keep the sound level meter and operator from interfering
with the measurement. Not only can the instrument
body and operator's presence block sound coming from
a given direction, but they can cause reflections that
may cause measurement errors. You may never have
thought of your body as a sound reflector, but experiments
have shown that at frequencies of around 400 Hz,
reflections from a person may cause errors of up to
6 dB when measuring less than one meter from the person"


Perhaps Ethan will have a reason for that 200Hz commonality? I reckon US rooms would in general be much bigger than Irish ones.

DD