Some additional perspectives from others that might be interesting to consider:
@j_j
Fundamentals of hearing 2004
https://www.aes-media.org/sections/pnw/ppt/jj/jj_aes04_ts1.ppt
“Various people have reported, sometimes anecdotally, that above 40Hz (and below 90Hz), although one can not localize a sound source, differences in interaural phase can create a sensation of space.. his suggests that for accurate perception of space, 2 or 3 subwoofers may be necessary. This also, as in many other places in audio, creates a situation where what one might consider the “optimum” solution (maximum bass flatness) does not in fact convey the perceptual optimum.”
Soundfields vs human hearing 2012
https://www.aes-media.org/sections/pnw/ppt/jj/soundfields_vs_human_hearing_edited.ppt
“Specifically, although one can not LOCALIZE signals below about 90 Hz, one can detect spatial effects from interaural phase differences down to about 40Hz. The AT&T Labs “Perceptual Soundfield Reconstruction” Demo, no longer available, contained a very nice example of these effects, and how they can change “boomy bass” in the 2-radiator case into “bass spread about a room” in the 5-channel case.”
@Thomas Lund
https://www.genelec.com/-/immersive-monitoring-a-perceptive-perspective
“From 50 Hz to 700 Hz, however, fast-firing synapses in the brainstem are responsible for localisation, employed in a phase-locking structure to determine interaural time difference (ITD). Humans can localise at even lower frequencies, but we will come back to that in a specific ultra low frequency blog.
The ability to position sound sources with precision spherically is a key benefit of immersive systems. Another is the possibility to influence the sense of space in human listeners. For the latter, the lowest two octaves of the ITD range (i.e. 50-200 Hz) play an essential role; but may be compromised in multiple ways”
https://www.genelec.com/-/blog/how-to-analyse-frequency-and-temporal-responses
“With both stereo and immersive, for your room and system to be able to reliably convey the envelopment latent in the content, perceived-direct sound should dominate in the 50 to 700 Hz range – where audible patterns characteristic of the recording space may have been picked up. If they have, you can be sure that the recording engineer has gone to great lengths in doing so. Fig 2 is a recording setup in Olavshallen in Trondheim, Norway, and shows a main mic array with sufficient distance between capsules to capture LF differences and moving patterns – two of the most precious qualities of a hall to preserve….Fig 3 shows the GRADE graphs from section 4.3 of the report, and reveals a monitor to the left which is able to convey envelopment latent in the content; and one to the right that is less able to do so. If listening to the latter, you are unable to judge recorded space precisely. Such ability may also be sacrificed when relying on bass management with only one subwoofer to reproduce all LF sound, rather than multiple channels and acoustic in-room summation. If possible with delicate content, don’t use a higher bass management cross-over frequency than necessary, and preferably below 60 Hz.”
https://www.audiosciencereview.com/...view-room-eq-setup.26397/page-21#post-1526313
“It's not primarily about localization, more about reproducing the swirling LF patterns a fine concert hall generates when music is being played. With acoustical summation in a reproduction room, there is a chance of hearing them, while electrical summation surely kills such joy. Also, we actually localize all the way down to a static pressure change (DC). It's indoor conditions messing up our senses”
https://www.audiosciencereview.com/...view-room-eq-setup.26397/page-21#post-1524620
“To faithfully reproduce great acoustic recordings, a flattish frequency response of perceived-direct sound is just one of the goals. More importantly, to me, the monitoring room and sound system need to convey moving patterns of sound latent in the recording, especially between 40 and 200 Hz. This is where to hear the soul of a concert hall or church, in case it has been recorded.
Collapsing discrete channels to a single sub channel should therefore be a last resort, e.g. if the reproduction room/placement is difficult and/or to accommodate multiple listeners.
Taking advantage of discrete channel reproduction at low frequency has even spread outside acoustic recordings. Top pop/rock productions now also make use of such perceptual excitement, which will remain a secret to “collapsers”
