by Anthony Grimani
Every so often a new film sound format comes along. Most last just long enough to generate a few movies; a few actually become the next industry standard. Some have everything to do with a crying need, while others result from smart people just thinking too hard.
I would guess there have been more than 30 multichannel sound formats over the years, ranging from two channels on variable-density optical film to seven channels of digital audio printed on the edges of 70mm film. I’ve had the good fortune to attend industry launches for some of these, including Kodak’s ill-fated Cinema Digital Sound, DTS’ mostly retired CD ROM synched to film, and the ubiquitous Dolby Digital format that is still around today.
When I was invited to witness the latest offering from Immsound in a demonstration at the Pacific Theater in Glendale, CA, I was obviously curious to see what the hoopla was about.
The Immsound demonstration of a new audio format for 3D movies was held recently at the Pacific Theater in Glendale, CA.
The push toward more 3D movies has generated talk about adding enhanced sound formats that produce more lifelike sound throughout the auditorium. Current formats do a pretty good job creating a 360-degree “ring” of sound around the audience, but the sound always stays on the periphery of the auditorium anchored by speaker locations. That’s OK for action on screen, but not if you want to make a sound effect follow a 3D effect in and out of the screen plane. Good sound designers and mixers can fool you into believing that a sound is traversing the room by using transition tricks that match picture effects, but you are in fact coerced into believing the sound effect. I was excited to hear if the new Immsound 24.1 channel process cracked the code on placing a sound right next to me – and everyone else.
That’s the real challenge, after all. You can create time- and phase-based 3D sound tricks that work within a restricted sweet spot, but can you achieve that at every seat in the house?
The Immsound folks have developed a sound production scheme based more on image and location rather than loudspeakers and channels. A software plug-in for Pro Tools (the most common sound production and mixing tool) allows the mixer to specify a sound location. The software then maps the signal out to the appropriate array(s) of speakers around the auditorium to achieve the desired result. There is also an iPad-controlled workstation with a graphical user interface that shows the locations of all the sounds in the mix. The multiple signals coming off the production tools are stored on hard drives with the picture data.
In the cinema, Immsound processing hardware feeds the signals to 24.1 channels of speakers. This includes eight channels arrayed on three horizontal levels behind the screen and five omnidirectional clusters on the screen. The remaining speakers are arrayed along the side and back walls of the auditorium at varying heights and depths.
So what does all this added firepower give us? Does Immsound achieve the promise of fully spherical soundscapes?
The 30 theaters worldwide equipped with Immsound will undoubtedly give audiences an experience that surpasses 5.1 or 7.1. But truly 3D sound it ain’t…yet.
The Pacific Theater demonstration featured remixed film trailers, promo films, and other techie propaganda. What I heard was impressive resolution of surround soundfields. The ability to pan a sound from front center to left-side, up and over my head to the right side, then to the back of the room was uncanny. The amount of sound off screen contributed to anxiety that truly heightened suspense just when it was needed. But at no point did the sound actually make it into the middle of the room. The soundfield stayed at the walls, ceiling, and screen – just as with other current formats. It makes sense; that’s where the speakers are. The human ear-brain system is amazingly adept at determining distance to a sound source; that’s how we stay safe and alive. In one of the clips, a large boulder came crashing down near us. Alas, the sound was around us, rather than scraping by our ears.
The 30 theaters worldwide equipped with Immsound will undoubtedly give audiences an experience that surpasses 5.1 or 7.1. But truly 3D sound it ain’t…yet. Immsound is working on the upcoming movie The Impossible (about the 2004 Thailand Tsunami) with Ewan McGregor and Naomi Watts. The trailer showed heightened spatial resolution in the surround soundfield that was really fun. I���m sure the movie will be that much more terrorizing and suspenseful, but I was hoping to actually hear the wall of water going right by me. Maybe that’s something I should just leave up to my imagination for now – like the mental images from a well-written book!
Anthony Grimani is author of the Home Theater column for Residential Systems and president of Performance Media Industries, a California-based acoustical engineering firm specializing in home theater design and calibration.
