Or, as has been the case with most of these modes (ever since the Yamahas in days of Yore with their “concert hall“ and “70mm cinema” settings) does it just make everything sound like one has ones head in a bucket?
The intent is to create virtual speakers for speakers which are absent as opposed to try recreate what you'd hear if within a different room or venue.
Dolby Height Virtualization is actually something targetted by Dolby towards being used in soundbars as opposed to AV receivers. Why would anyone buy a 9 channel AV receiver and then not utilise those added channels of amplification?
Dolby Atmos sound bars with height virtualization
Dolby Atmos height virtualization processing leverages Dolby’s deep understanding of human audio perception to simulate an immersive audio experience while using fewer speakers. For height effects, virtualization is used to create the sensation of sound above you, originating solely from listener-level speakers. For systems without discrete surround speakers, virtualization of surround effects is employed to create enveloping, 360-degree audio without speakers behind or to the side of the listener.
On a technical level, Dolby Atmos height virtualization applies carefully designed height-cue filters to overhead audio components before they are mixed into listener-level speakers. These filters simulate the natural spectral cues imparted by the human ear to sounds arriving from overhead. For surround virtualization, a combination of head-related transfer functions (HRTFs) and cross-talk cancellation are employed to approximate for the listener’s ears the binaural cues of surround speakers. For both types of virtualization, special care has been taken to equalize the associated filters so that the timbre of the audio remains natural anywhere in the listening environment.
This illustration shows the difference between the Dolby Atmos virtual experience and the traditional sound bar experience.
Content encoded in Dolby Atmos will provide the most realistic audio effect from a product that delivers the Dolby Atmos experience. The discrete height elements in the Dolby Atmos mix feed the Dolby Atmos height virtualizer, are processed by the algorithms, and then mixed in to the corresponding listener-level speakers.
Dolby can support a number of output configurations with the Dolby Atmos height virtualizer, using 2 to 7 listener-level channels to create the sensation of either 2 or 4 overhead speakers.
Note the use of Dolby's favourite HRTFs.
What is a HRTF?
Dr. Edgar A.G. Shaw became best known for his research in understanding the acoustics of the external ear. It was he who scanned the sound field in human ears using a tiny probe microphone with sounds arriving from different angles, and plotted the details of what we now call HRTFs. This is all documented in Journal of the Acoustical Society of America papers, and Dr. Shaw received the Raleigh Medal Award for his work. The cues for sounds arriving from above are associated with directionally sensitive resonances in the external ear in the frequency range of about 7 - 12 kHz. They can be very different for different people because our ears are all physically different. Taking an average of many ears though, one finds a general trend indicating that as a sound source is elevated on the median plane (directly forward in this case) there is an increase in sound level reaching the eardrum at frequencies around 7-8 kHz. There is another directionally sensitive resonance in the external ear around 12 kHz, but it is much less predictable because as frequencies get higher smaller physical differences between pinna result in greater response variations between individuals.
Dr. Shaw estimated that the dominant height cue could be modeled by a resonance centered at 7.5 kHz with a Q of about 3. A level increase of about 10dB would correspond to an elevation of about 45 degrees. To put this into perspective, this work was done in 1972, 42 years ago, so none of this is breaking news. A very perceptive final comment was “For this to work without special attention to the idiosyncrasies of the subject [the listener] it would probably be necessary to use a broadband source (e.g. white noise, clicks, etc.).” Clearly this phenomenon was well understood many years
Conclusion
It seems very apparent that the deployment of a HRTF in a loudspeaker crossover is not only problematic but likely not necessary as well. While they are useful in applications like headphones, and sound bars, adding them to an actual discrete external sound source like a loudspeaker playing in a room, and specifically in this case, a Dolby Atmos Elevation speaker module, can in fact impact performance in a negative way. Moreover, this also unnecessarily drives up the complexity of the speaker’s crossover and thus its associated cost. The human ear already has the benefit of its own HRTF customized to each listener. Simply selecting a loudspeaker with narrow and controlled dispersion, along with careful placement relative to the seated area can create the illusion of elevated sound for a narrow listening area, though not as precisely or as consistently as having a discrete sound source located in the position of origination it was intended to mimic.
Dolby Atmos Elevation speakers employ a HRTF in their analog crossovers in attempt to trick the brain into perceiving height. But is this really necessary or can it degrade their sound quality?
www.audioholics.com
Note that the conclusion suggest that their use may be favourable within soundbars, but that is on a gardware level and with it incorporated in the the speaker's own crossovers.