4.3 – What about sound?


The exciting stuff that awaits us…

When it comes to the future of going to the movie theater, great things are happening as we’ve seen so far. The movies themselves diversify, High Definition shooting is breaking boundaries with 48 and 60 frames per second, and science is well on their way to creating dynamic holograms in order to revolutionize filmmaking. But when we look closely, all these innovations and changes cover the visual aspect of the movies. So what about sound? Dolby 5.1 set the standard for years and now there’s Dolby 7.1. Wouldn’t 3D sound be awesome?

As we all probably know, Dolby has been dominating the movie theaters for over 40 years now. In 1971, Stanly Kubrick’s classic A Clockwork Orange was the first movie ever to be shot with Dolby-sound. Ten years later, the same system was used in over 6000 theaters worldwide and it never left Hollywood.

Dolby 5.1 was a great innovation that got the crowd excited, because it offered true surround sound from 6 different speakers that surround the viewer. That technology has set the standard once more, and had been popular ever since.

So recently they came up with Dolby 7.1! What´s different? Well, it creates 4 different ‘surround-zones’ in the theatre. The four zones take the conventional Dolby 5.1 system, and add Back Surround Left  and Right zones to create the best sound experience, wherever you’re sitting in the theatre. What that basically means is that they optimized their current system. This is relatively easy to incorporate in theatres because it´s as simple as “updating the firmware in the cinema processor and replacing an audio cable”. So is it a great improvement? Definitely. Is it revolutionary? I’m afraid not. Don’t think that I’m trying to diss Dolby here, I’m not. I’m sure a lot of bright minds and a room full of technicians worked hard on this system to make it perfect. I’m just saying that when you look at what’s changing with the visual part of movies, sound is simply falling behind.

Professor Edgar Choueiri

So what revolutionary innovation is going to change the game? The answer might lie with Professor Edgar Choueiri – Director of the Electric Propulsion and Plasma Dynamics Laboratory of Princeton University. His hobby is acoustics, and for a while now, he has been exploring ways in which we can truly hear in 3D. Not with 1000 speakers in the room or with headphones on, but through two ordinary speakers.

And that is immediately one of the ways it’s different from surround sound. It only uses two speakers. Surround sound also wasn’t invented to create 3D sound. It is beautiful for adding effects in an action movie, but as the professor describes, it cannot let you hear a person walking up to you and whispering in your ear. The sound is still at the speakers. With the 3D technology, the prof can give you the illusion of a fly circling around your head with only 2 speakers.

3D Sound

So how is it different from surround sound? Well, the reason why we can’t really hear in 3D through traditional sound systems, is Crosstalkbecause of a phenomenon called “Crosstalk”. When traditional recordings try to incorporate location information, what they do is produce sounds from the right speaker that are only meant for the right ear and vice versa. The problem with this approach is that you can still hear sounds from the right speaker with your left ear, and the other way around. This ‘pollution’ is called Crosstalk. That is the reason why sound is not as three dimensional coming from a stereo recording, in comparison to what your ears and brain pick up in reality. The challenge that professor Choueiri is focusing on, is to cancel out this crosstalk while maintaining the quality of the recording. And he did.

Crosstalk cancellation

Professor Choueiri  devised a digital filter that doesn’t require special recording or playback equipment and can be played on any set of speakers. The filter cancels the crosstalk effect and enables the professor to create a sound anywhere he’d like in the listener’s perspective. Check out the full video to find out more.

This of course is a beautiful revolution for the way movies are recorded and can really give the viewer the illusion of being part of the movie. But better yet, think about the improvement this technology can be for people with hearing aids. When you think about that, this tech will probably save lives.

– written by Stefan Volders (Blog Post #3)

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