Of course, they do not compare the acoustic absorbtion with purpose-designed materials nor do they indicate the quantity of plants needed to produce the measurements.
That's a great link. Thank you for posting it. It tells pretty much everything one needs to know in order to choose the correct plants for his/her application.
I don't care whether or not they work quite as good as expensive sound absorbing panels. The website tells you which plants work best to absorb certain frequency ranges. It even tells you what kind of environments they like and has pics of the plants, as well. I consider that valuable information.
My wife loves plants, but she'd kill me if I started putting sound absorbing panels all over the living room!