DTS agrees with you and provides support for authoring and playback of DTS-HDMA BDs with a 7.1-CenterOverHead speaker layout, which includes a "voice of God" speaker. However, I'm not keen to mount a speaker over my head, so I'd be more likely to choose the 7.1-CenterHeight speaker layout [designed to mimic IMAX] as a safer alternative. Of course, no existing home receiver supports either 'alternative' speaker layout.
I'm wondering what type of listening differences would result in using Dolby's Front Height speaker configuration vs. a Center Height speaker vs. a 'Voice of God' ceiling mounted speaker(s) for IIz? Has anyone found a white paper describing IIz processing?
From the information I've been able to dig up its seems that height is only processed from Ls & Rs (left & right surround) and in IIx also Lrs & Rrs (Left/right rear surround.) It's non-directional, uncorrelated and amplitude filtered. Sound suspiciously to me like 6.1 center back surround (in phase and equal information in the Ls & Rs...) This is possibly where IIz encoding is done. Maybe if run my 6.1 center back channel to ceiling speakers/upper front speakers I could get pseudo-IIz! LOL I'm more inclined to think that ceiling mounted speakers would be more effective for IIz if you want to give more localization to overhead sounds better (ie plane flyover.) Personally I think 5.1/7.1/IIx is sufficient for general ambiant sound. The front height directs probably most of audio over the listener's head to reflect off ceiling/rear with varying results due to room size/shape etc. May have desired dispersed effect but is that what you want from a height channel?
From Dolby.com: "Because it processes only nondirectional sounds for the height channels, Dolby Pro Logic IIz maintains the integrity of the source mix and the effects are always appropriate to the material."
"Dramatic alternative listening perspective for installations that can't accommodate back surround speakers"
"Functions with original stereo or multichannel sources"
"With Dolby Pro Logic IIz, developers can encode specific height information in the z-axis. "
"Dolby Pro Logic IIz processes low-level, uncorrelated informationsuch as ambience and some amorphous effects like rain or windand directs it to the front height speakers."
From another webboard posting:
Supports the following upmixed output configurations based on 5.1 sources with independent Ls and Rs channels:
5.1 to 7.1 Height [Ls, Rs to Ls, Rs, Lvh, and Rvh]
5.1 to 9.1 [Ls, Rs to Ls, Rs, Lrs, Rrs, Lvh, and Rvh]
Note: For 5.1-channel sources, Dolby Pro Logic IIz height extensions operate only on the Ls and Rs channels; L, C, R, and LFE channels are bypassed.
Because new formats (such as Blu-ray Disc) allow content to contain up to 7.1 discrete channels from Dolby Digital Plus and Dolby TrueHD audio programs, the height extensions support 7.1 Back sources and offer the following upmixed output configurations:
7.1 Back to 7.1 Height [Ls, Rs, Lrs, and Rrs to Ls, Rs, Lvh, and Rvh]