per wiki, an acoustic anechoic chamber is
a room designed to absorb as much sound as possible. The walls consist of a number of baffles with highly absorptive material arranged in such a way that the fraction of sound they do reflect is directed towards another baffle instead of back into the room. This makes the chamber almost devoid of echos which is useful for measuring the sound pressure level of a source and for various other experiments and measurements.
Does an anechoic chamber take mainly effect on the sound from inside or outside the chamber? Are there some measurements about the effect that an anechoic chamber takes on the sound from inside or outside?