Flanking in your walls
The consequences of architectural design. What a concept!
Designing for confidential privacy is the same thing as designing so your neighbor isn’t experiencing your music!
Knowing where you are in speech levels gives you an idea of what you are going to have to do to get your frequency levels down to an acceptable level. If you can hear the neighbors, the neighbors can hear you!
Flanking over party walls is very common in apartments and can be found in many parts of a typical residential or commercial structure.
The video talks about building more robustly. In this case it is referring to adding more mass to the ceiling and to the wall area to push down the audible speech levels.
To take this one step farther, adding enough mass with the proper de-coupled methods will not only push the audible speech frequencies down to a lower threshold, it will also contain or isolate the lower bass frequencies known to be the biggest part of sound disturbance in apartment dwelling.
To isolate the frequencies and SPL that musicians are used to generating, the walls have to go to the upper deck. At least in a one leaf type construction. Naturally in a standard two leaf, or room with in a room construction, your exterior walls would go to the upper most part of the structure and the interior walls would go to the separate ceiling being constructed for the inner box.
But to construct a room in a room on the upper level of an apartment building is not something that will ever be built without serious money. Even then the issues associated with an upper level decoupled build will go up against many obstacles.
To continue your understanding of flanking, where it is and how to address the paths, continue to the document “Airborne Sound Insulation in Multi-Family Buildings” provided by the National Research Council Canada.