Originally Posted by kwarny
There are many confounding factors. I think people are overlooking that. This is not controlled so the most we can make of this is wonder why something happened to develop a hypothesis.
The BHD is composed primarily of subsonic content. I thought the feeling was subtle. It would most likely be better with more displacement though. If this content was present in other clips, it would probably make a subtle change. The Submersive was also the most preferred on the Kid Cudi song (intense pressurization). However it might of been at a slightly louder playback volume. The Kid Cudi song only plays down to 40 Hz but we felt the impact of this.
I have other questions such as:
If we can feel the 40 Hz content greater then the under 20 Hz content in this scenario, would a sub pushed harder producing lets say second order distortion 10dB down from the fundamental increase the pressurization also?
If a sub seems to last longer in the time domain, does the listener feel more pressurization since the frequencies are present longer?
I felt the chairs shaking many scenes. Does the listener associate the resonating of the chair as pressurization?
Wish I was still in the EE program, I could of got funding to maybe actually conduct a controlled study useful to many
. It would provide a start but multiple trials would still need to be conducted.
I read your write up with a lot of interest. Great job, and thanks for that.
I was most interested in your comments because your sub had an equally flat response to 10 Hz (unfortunately, the bottom of the graph), that being the only other sub in the group besides the SM with that distinction.
Being that the SM has dual 15s and around +8dB more juice, I believe that made a significant difference in the presentation. Since SPL can easily be equalized by multiples, there should be little difference if that were the case, IMO. It would be interesting to hear about such a comparison some day using multiples of Rythmiks to get to a specific playback level.
The sub that produces ULF at reference level doesn't seem to be lasting longer... it is lasting longer.
It's simple physics. A 30 Hz sound wave (33.3 ms) decays 6 times faster than a 5 Hz sound wave (200 ms). Therefore, wherever the FR of a sub may be arbitrarily rolled off, either by design or by the limitations of its alignment, is the biggest contributor to sonic signature with playback of full BW source.
Ringing is a different phenomenon and should be fairly easily differentiated from ULF decay times because it occurs in an audible range of frequencies.
Here's a SL comparison of my sub mic'd at the listening position vs the digital feed from the player of the lightning strikes in WOTW. You can see that it's a very good reproduction of the ones and zeroes, but notice that the mic'd version decays much slower than the digital version (at the far left, lowest frequencies):
I wasn't awrae of the phenomenon until I looked closely at these graphs, otherwise I would have noted the scroll speed and the time interval to match them up against 4 Hz, and some day I will actually do this more scientifically.
With ULF (say below 15 Hz), the chair (or whatever else in the room) doesn't resonate. A chairs resonant frequency is well above 20 Hz. Contrary to the vernacular, subwoofers don't "move air". They send a pressure wave outward using the air as a medium. The air molecules compress and then expand as the wave moves through it. If this pressure wave is strong enough, it can cause the walls, floor, chair, etc., to 'move' in reaction to the pressure wave. This can definitely be felt and is different from the same effect caused by a much higher frequency (say 40 Hz) sound wave. 'Vibration' is probably a better word to describe the effect of a higher frequency effect, added to the fact that the higher frequency effect is audible and the ULF is not.
I agree that BHD is less effective. That's because it's ULF (6 Hz and 18 Hz) are a constant tone. What many new sound designers seem to have discovered is that ULF is much more effective in pulses and bursts. Star Trek uses this effect very effectively and the pulses and the subsequent room reaction are unmistakably present, whereas the constant drone of a ULF frequency is a completely, and as you put it, more subtle effect.
Star Trek; Romulun ship emerges from the black hole in Ch 1:
Another thing to consider is that, like BHD, a lot of designers use naturally occurring sounds (like the chopper blades in BHD) or create sounds that have multiple tones, a la harmonic distortion. BHD is comprised of 6 Hz, 3HD (18 Hz), 5HD (30 Hz), etc... So, with many of them, it's impossible to notice harmonic distortion because it's masked by the tones of the effect.
If a sub produces harmonics that are still in the <20 Hz range (for example, a 5 Hz burst would have 2HD of 10 Hz and 3HD of 15 Hz, all inaudible), then yes, it would actually add to the effect, although when you are talking about tones that are below hearing, 10% or so is not that significant. So, no I don't think it makes a lot of difference unless the sub is producing very high harmonic distortion in the first 2 octaves.
Just thought you might be interested in some of this stuff, and wanted to thank you for your input.