Incredible important information... Thanks Hilde...
I think my research are motivated among other papers by this Russian Paper of 2017...I just begun this video about Helmholtz resonators too ...
I used 100 tuned Helmholtz resonators in my past room... The results were stunning with a soundfield filling my room and the speakers were disapearing... I used also many others devices though to contribute to this as experiments.
https://www.researchgate.net/publication/318280591_Sound_Absorption_by_a_Helmholtz_Resonator
Incredible information in this video about the increase of heart pressure and 10 decibels of sound too much...
I used also many Schumann generators ( low cost) 13 of them and it is easy to spot the impact when well located in the room or near the gear...
I stopped talking about these here because too much idiots harassed me with insults... I am not patient then i reacted too much....😁
But with this interesting information to study i will be able to talk about this anew if necessary ...
Thanks hilde45....