Direct View Displays bring high image quality in the cinema but suffer from lack of cohesion with front channel sound which is, in theory, supposed to come from the same location as the picture. At this stage, the main speakers are typically placed above the direct view display and the sound coming from them doesn’t perfectly match with the picture. After all, the dedicated speakers are still called “screen channels”.
Cinema projection systems are much better in that regard because of the speakers’ traditional placement behind the screen. However, audio quality is compromised because of the perforated screen which could be considered as an obstacle letting only pass a given portion of the sound. Some of the consequences are well known: Comb filtering effect, lack of intelligibility, poor auditorium coverage.
With the advent of objet based soundtracks in cinema, the difference in terms of quality between the sound coming from the screen channels and the surround speakers has become even more obvious though compromises in sound quality have never been fully quantified since perforated screens had always been needed for cinema audio until very recently. Now that high quality cinema audio system are available which are not requiring perforated screens, it appears necessary to quantify these effects.
In this article, we are evaluating the auditorium sound coverage by taking frequency measurements at different locations of a movie theater (center, sides and corners) for sound coming from the typical 3 screen channels through a traditional perforated screen, then with new technology emitting sound in front of the screen. The purpose of those measurements is to demonstrate that even members of the audience not seated inside the usual “sweet spot” area can enjoy the sound mix, including information coming from speakers located at the opposite side of the room, in addition to better sound transitions from the screen channels to the surround channels.