INFRASONICS - A Missing Dimension in Reproduced Spatial Audio Realism

We live in times when Spatial Audio is gaining immense popularity. Adding accurate positioning to sonic objects in a recording and reproducing it in a way, that the listener perceives and localizes the source of sound precisely, is considered to be an area of great interest with a plethora of application areas like creating soundscapes for virtual reality environments, music production, movie soundtracks, etc.

In the cinema domain, we have had surround sound systems for a long time now dealing with exactly this idea and newer formats like 杜比实验室 #Atmos, #DTSX, etc. have been doing the same in better and more precise ways due to their "object-based" surround sound architecture.

Ultimately, it's all being achieved by controlling and changing the ITD (Inter-aural Time Difference) & ILD (Inter-aural Level Difference) parameters of sonic content, based on a solid understanding of psycho-acoustics. All of this is dealt with, in the human audible frequency spectrum 20 Hz - 20 kHz; more precisely in the higher frequencies above 100 or 150 Hz, since Low Frequencies are generally not accompanied by a good sense of localization.?

This sensation is processed totally in the EAR Canal and the human auditory system.

However there are vibrations below 20 Hz which we don't "hear" (with EARS) but definitely do perceive "viscerally" (with our SKIN, if I may say so). Our experience of the "Real-World" is also built around this sensation, in a big way.

Every day, as I walk to my lectures, I pass by a construction site with a lot of activity involving heavy earth-moving equipment. If nothing, there is always the Jack-hammer going on in full swing. When I close my eyes & pay keen attention to the sonic scene, my perceived soundscape is NOT comprised ONLY of those vibrations that go into and are sensed by my EARS; But the vibrations seeping into and travelling through my body is a prominent sensory experience too, which actually completes my "Feeling of REALISM" and perception of my environment. I am grasping my surroundings even with vibrations below the lower limit of the audible frequency spectrum.

The same goes with the sound of thunder, a roommate slipping and falling on the floor with a THUD, an annoying neighbor living upstairs skipping rope at midnight, a horse galloping past you with its hooves hitting the hard ground, an elephant running towards you, a heavy truck passing by on the road, a large turbine running at full speed, a car engine revving near you, and so on.?Even if you were to move your table across the room dragging it along the floor, there is a lot of infra-sonic vibration that our body perceives from the activity.

I also realize often that the visceral sensation of vibrations in the environment is much more prominent with sounds originating at a distance caused by vibrations from heavy, impactful objects at the site.

While watching the #Oppenheimer in IMAX a couple of days ago, when the #TrinityTest goes off, though I enjoyed the timing and the dynamics of the explosion, I was also faced with considerable disappointment. It simply did Not feel "real" enough for me. It was all about being able to HEAR the explosion, but NOT FEEL-ing it. Being from a town in #India, which is famous for its loud and "explosive" fireworks display, my experience of an explosion is equal parts VISCERAL as it is AUDITORY.

So, it is clearly a lack of #INFRASONICS here, i.e., a lack of vibrations below 20 Hz in the room with enough energy in them, to move my body to make me feel what I would feel, if I were at Los Alamos as part of the crew of J. Robert Oppenheimer himself.

I wonder, how close we are really getting to "realism" with the current Spatial Audio reproduction mechanisms?

Shouldn't we be really thinking about taking INFRASONICS also seriously, when we talk about Spatial Audio Reality?

I do understand and agree, that it is quite complex to achieve it in real-world listening environments. Especially when the listening rooms/spaces get larger, it's even harder to pressurize air enough, in such a large space, keeping all the dynamics intact, and yet be impactful on every single person in the room. Perhaps, there could be some use of #haptics or other technologies which could make this objective more achievable. #infrasonics in portable audio setups is a challenge, too.

For smaller and more intimate listening spaces, there exist infrasonic subwoofer options like these from ASCENDO Immersive Audio GmbH , The80 SUB PRO PASSIVE and the likes. For larger spaces, a different approach might have to be considered to actuate infrasonic vibrations.

The need for infrasonics in our sound reproduction systems has been brewing in my head for a long time now and the small #Oppenheimer disappointment and also randomly coming across this video on my YT feed, motivated me to write this post:

The Inaudible Sounds That Make Movies Scarier - Cheddar Explains

Please share your views and ideas on this topic in the comments. Tell me if you think we need #infrasonics or not, to complete the puzzle of #spatialaudio.