to minimise echoes and room reflections of sound waves.The goal of active psychoacoustic control is using direct waves and early and late reflections in a positive way and timing them to create at will the adequate imaging, soundstage, and a ratio for the listener envelopment (LEV) and source relative width (ASW) factors that will be optimal...
Then thinking about minimising reflections or neutralizing them is not enough and not very powerful in a small room....
The positive use of reverberation is key.... But it takes more than just a balance between absorbtion,reflection and diffusion... This is elementary passive material treatment....
Complementing it and more powerful is the systematic use of Helmholtz resonators in a grid beginning near the speakers and around the room.... I use 32 pipes and tubes fine tuned... Results: spectacular control at will of the many acoustical factors... I called that "a mechanical equalizer"...No upgrade rival this save a very costly one... My system value is 500 bucks but does not sound at all like 500 bucks system ...
Regards...