I know you're ignoring me on this issue and have been for some time.
I'm sharing my nearfield experience and what my rational is. From personal experience, it's energy disbursement. The further from the energy source, the less one is able to perceive it's existence.
Flexture of the floor is a general transference, over a large area. Tactile sensation is a nearfield experience and one has to jack up the energy source to pass the sensation on down the line in the same way, dB falls off at 6dB per doubling of distance.
With the nearfield subwoofer close at my back, I feel lots of tactile sensation but the wife, two or three feet to my side, in a separate chair, doesn't feel anything in this regard.
(subwoofers; two FV15HPs)
(it's rude to intentionally ignore a sincere participant and if you will, if you don't wish me to participate in this conversation, man up and say so)
Too much eggnog Bee...
Not sure why you think I'm ignoring you...not on purpose if I've missed something.
I agree with you on the distance and energy theory as I stated below:
Based on this test here, it shows that SPL as measured by an SPL measurement device does not solely determine the tactile sensation for ULF. Even though the farfield subs measured at the same SPL as the nearfield subs, the couch shaking effect was much more pronounced with the nearfield subs. I had to increase the farfield subs by 20db to get a similar shaking effect. The theory is that acoustic energy is what primarily drives the tactile feeling, and acoustic energy is stronger when the distance is close and is produced directly from the sub (as opposed to SPL from room gain). SPL meters are not the right device to measure this acoustic energy. At this point, this is still an open question as to how this acoustic energy can be accurately measured.
Since nearfield subs drive the tactile feeling as compared to farfield subs, the frequency response of the nearfield subs should give a better representation of tactile feeling. In my room, the dual FV15HPs have the below nearfield response:
Based on the above, you would think I would have the most tactile feeling 25 and 50hz. I would also have good tactile feeling from 11hz to 18hz as well.
So I took the Vibration Meter and measured the vibration between the frequencies of 10hz to 80hz and plotted on a chart with the response of my nearfield FV15HPs. The main volume on the receiver as -20db for this test.
Here is the Vibration Meter scale (Mercalli scale):
1.0 - Instrumental. Felt by animals
2.0 - Weak. Felt indoors by a few people
3.0 - Slight. Felt indoors by several
4.0 - Moderate. Hanging objects swing
5.0 - Rather Strong. Dishes broken
6.0 - Strong. Heavy furniture moved
7.0 - Very Strong. Difficult to stand
8.0 - Destructive. Fall of walls
9.0 - Violent. Noticeable ground cracks
10.0 - Intense. Almost destroyed
11.0 - Extreme. Rails bent greatly
12.0 - Cataclysmic. Total destruction
As you can see by the pink line, I get the majority of the couch shaking in my room starting at 11hz or so to about 21hz. After that, the couch shaking levels out to barely any shaking at less than 1. You can see by the blue line, that the shaking does not match the frequency response entirely, especially past 20hz where I have the strongest SPL, but the weakest couch shaking.
I have two theories why this is: 1. The resonant frequencies of my couch, 2. ULF frequencies wobble the foundation of the couch (imagine someone grabbing the base of your couch and shaking) with slower vibrations, whereas the higher LF frequencies are quicker vibrations and more directional (e.g. back massage chairs) as well as have the kick in the chest type sensations. The ladder isn't accurately measured by a phone on the based of the couch and perhaps why it drops off in the audible frequencies. It would be interesting if I could somehow measure the shaking that is happening on the cushions behind your back, as I'm sure there is lots of shaking going on in the upper bass frequencies.
So we are good there.
However, this does not answer the debate around ported shaking more than sealed in my room. In the test reference in post #1412, the FV15HP and the FTW21 were placed in the same position nearfield behind the couch. Distance is the same.