Two problems that get confused constantly
Stopping sound from leaving and making a room pleasant inside are two different jobs with different materials. Foam on the walls does not reduce what the neighbour hears, and a heavy double wall does not make a control room reliable. This confusion is expensive because it leads people to pay for treatment that does not address the problem they wanted solved.
A control room is judged elsewhere
A good control room is not the one where music sounds most flattering. It is the one where the decisions you take survive the car, the phone and another studio. So we measure the response, but what we really check with clients a few weeks after commissioning is that test, because it is the only one that counts.