My question is a straight forward question that I ask simply because I want to understand something which has relevance to the ETF testing I have done in my own room.
BTW, I am not an acoustician but I think I understand some of the principles.
Please can it be explained to me how any result other than "how does this placement of rockwool absorb, in this quantity, in this orientation, in this room?" can be inferred from the waterfall plots.
You see, to me, there are too many unknown and unique variables in the room to enable the results to be interpreted in anything other than a vague way. For example, the construction methods, materials and dimensions of the room. For example, the cumulative interaction that surely must occur between the panels dependent on their positioning. For example, the interaction with the furniture in the room (this may not make much difference below 100Hz but it surely changes the room). For example, the gain level of the sweep.
To my level of science, if you want to measure absorption to any degree of absolute accuracy, then you need to do so in a room where (and I have no idea how this is done) the effects of the room are neutral or can be neutralised. If you do so in any other type of room, you are measuring relative absorption of the materials concerned against the characteristics of the room.
Does this make sense or am I talking nonsense?
As an observation, it would also have been interesting to see the results of Minitraps or Mondotraps put alongside the results of the bare panels.
Now, at the risk of being boring, I repeat that I have no hidden agenda here. I am asking a question because as my level of acoustics knowledge increases, I have more questions - how does that work, what if you did that? etc... My initial thoughts on this absorption test lead me to raise the points above. I hope that the question will be left to stand.
Thank you and regards,