"The mic locations are 3 on either side, corners excluded."
As you will see in the B&K video, our standard is different. They use 5 and 7 which suggests my memory of 4 and 6 with more allowed may be correct.
I don't have our standards in my Library, or software enabled. But from memory ISO requires locations not nearer than 1.2 M from any boundary.
There is some requirement for distance between locations, again I think 1.2M
You are right about my conflating speaker and mic locations, brain fart, but I guess different speaker locations would show up anomalies or problems. Might be needed to get by the 'qualifiers' in the various meters and software.
These memories may have been superseded, I do see Hemi speakers of late. PZM effect overrides Boundary reflection I guess. But Omnidirectional and less than a metre from a double boundary strikes me as contradictory. Also regular DoDecs are always on stands. Maximum room drive would of course place them in a Tricorner, but I have never seen that happen.
When you get a moment you might take a look at the recommendations in the ISO standard and let us know.
But here is an extract from our Gov on the recently introduced mandatory testing. I see nothing excluding corners here, and I do see a height variation.
This may or may not be the same as ISO guidelines, but I guess the requirement for 8-10dB excess over ambient needs to be achieved in any case. At least one other speaker position seems mandatory.
(An omni-directional sound source should be used which meets the directivity requirements of Annex A of I.S. EN ISO 16283-1. For each source position, the average sound pressure level in the source and receiving rooms is measured in one-third octave bands using either fixed microphone positions (and averaging these values on an energy basis) or a moving microphone.
For the source room measurements, the difference between the average sound pressure levels in the adjacent one-third octave bands should be no more than 8 dB.
If this condition is not met, the source spectrum should be adjusted and the source room measurement repeated. If the condition is met, the average sound pressure level in the receiving room, and hence a level difference, should be determined.
It is essential that all measurements made in the source and receiving rooms to determine a level difference should be made without moving the sound source or changing the output level of the sound source, once its spectrum has been achieved.
The sound source should then be moved to the next position in the source room and the above procedure repeated to determine another level difference. At least two
positions, at a minimum 1.4 metres apart, should be used with each source position also varied in height by at least 0.7 metres.
The standardised level differences, in one- third octave bands, obtained from each source position shall be inverse-energy averaged to determine the level difference, DnT according to equation 6 of I.S. EN ISO 16283-1.
A.2.3 Measurements using multiple sound sources operating
simultaneously
Omni-directional sound sources should be used which meets the directivity requirements of Annex A of I.S. EN ISO 16283-1. The sound sources should be driven by separate and uncorrelated signals and adjusted so that each sound source is of a similar level.
The average sound pressure level in the source and receiving rooms is measured in one-third octave bands using either fixed microphone positions (and averaging these values on an energy basis) or a moving microphone.
For the source room measurements, the difference between the average sound pressure levels in the adjacent one-third octave bands should be no more than 8 dB.
If this condition is not met, the source spectrum should be adjusted and the source room measurement repeated. If the condition is met, determine the average sound pressure level in the receiving room, and hence the level difference, D as defined in I.S. EN ISO 16283-1.)
