One more question on triple leaf

Hi to everyone, can anyone please tell me if the situation depicted in the figure is configured as a 'triple leaf'? The main difference with the situations described in other threads is that the space between the room 1 and room 2 is not air tighted. So I wonder if it is advisable to remove the central leaf as in situations where the walls touch the ceiling. Thanks for the advice.

The main difference with the situations described in other threads is that the space between the room 1 and room 2 is not air tighted.

Yes, that is a 3-leaf system. Being sealed or not does not make much difference in defining if it is or is not a 3-leaf systm. If there are two large massive surfaces with an air gap between them, that is an MSM system and both surface are leaves. If there are three large massive surfaces with two air gaps between them, then it is a 3-leaf system. Air is a spring, regardless of whether or not it is sealed into an air-tight box. If air was not springy, then sound would not exist! The collisions between air molecules MUST be elastic: if not, sound waves would not be able to propagate through the air. When one molecule strikes another, it must transfer all of its energy to that second molecule, and bounce back to where it was before. If there is no energy transfer and no bounce-back, then there is no wave: no sound. So air is always a spring, even when it isn't trapped in an air-tight cavity. So yes, what you show there is a 3-leaf system. - Stuart -

Thank you very much Stuart, as always your suggestions are very useful and professional.