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Guide: Create a 3D sound environment

The technologies capable of extending the 3D effect to the soundtrack of movies and games on your home theater.

The image is often considered more important than the sound for the industry and the public in general. The justification for this lies in the physiological, psychological and even sociological related to the sense of vision, responsible for 80% of the information received from the external environment, while the hearing has only 10% . However, audio and video have always gone together since the days of silent cinema, where the notes of a piano served to accentuate the drama of a movie and thrill the spectators.

In 2009, with the start of sales of 3D TVs in the global scenario, the industry began to wonder about what to do to get the attention of consumers also for audio. With the growing demand for screens, games and mobile devices, some technology companies are already working on solutions designed to deliver the user an immersive sound experience through products with only two speakers. To piggyback on this trend, manufacturers who produce traditional stereo systems and 5.1-channel audio with DSP effects, including 3D mode, came to emphasize and exploit this resource type.


For HTBs, the novelties consist in a more efficient processing algorithm for  three-dimensional audio playback and tall boy speakers  or satellites with extra  speakers positioned either at the top (facing the ceiling) and the back of the box. The goal is one: to create a sound that engages listeners in filling a 360º environment (a small one) more broadly. That’s why some manufacturers come to claim that their systems have 7.1 and 9.1 channel integrated sound when physically they offer no more than 5.1 channels, with additional simulation.

Tests done with key models showed that due to numerous reflections suffered by sound waves, in practice the 3D sound loses a little definition and the feeling  needs to split channels obtained with Dolby and DTS processing. The situation may be aggravated in musical reproduction, where the location of the instruments is not always realistic but artificially recreated, which compromises the quest for soundstage. Moreover, with 3D sound enabled only for surround effects, omnidirectional involvement results in more dispersed and immersive audio to listeners.


But for a sound experience in 3D home theater, without compromising sound definition during the playback of tracks and music content, the new generation of receivers come equipped with a technology capable of generating a new dimension to surround sound. The Dolby Pro Logic IIz was launched three years ago, but only now is beginning to be implemented by installers and users in home theaters with new receivers.

The current Receivers have the DPL IIz processing, which creates a greater audio spatiality and dimensionality through speakers installed just above the front left and right (front height), forming a system 7.1 or 9.1 for movies, music and games. Take it easy, it is not necessary to use similar speakers to the traditional ones by the operating system, but compact and the same brand and line of existing models.

The advantage of the DPL IIz is that to the reproduction of those front vertical channels is not required new types of specially encoded content. Instead, the processor works on stereo or 5.1 signal to add depth and dimension without affecting the integrity of the original mix made by the producers of content – from movies or songs. Another benefit of DPL IIz is the adaptation of a 7.1 setting in rooms with limited spaces or open areas where it is not always possible to accommodate surround back speakers.

Like Dolby, other companies have also developed processes in order to fill the acoustic environment and make and create a sound with more spaciousness. This is the case of Audyssey with the DSX, present on some models from Denon and Onkyo, which expands stereo or 5.1 channels to the front vertical (7.1), and back surround (9.1). What is new, however, is the presence of another pair of front speakers, called Wide Fronts.

The Audyssey came to the conclusion that the first reflections on the side walls play a large role in the subjective impression of listeners. Therefore, the need for installing speakers at an angle of 60 degrees from the front of the room.

Similar configuration is found in the newest technology DTS Neo: X (officially announced in June), also for up to 11.1 channels, present only on 2012/13 line from Onkyo, but it promises to be part of car sound systems. The differential DTS Neo: X is the inclusion of side speakers, almost beside the couch.

Why use more speakers to the sound in 3D?

According to research done by the companies involved, including a vertical dimension in a home theater with 7.1 system brings a greater sense of realism than the inclusion of surround speakers in the horizontal plane. People are much more sensitive to directional ranges of sounds that occur in front than behind them.

Also according to researchers, human hearing can hear a lot more sense than the current systems offer. Does the use of additional speakers facing the audience that there will be better understanding of the sound to the location of the effects and at the same time, the reflected sound to have a sense of the size of the studio or space (spatiality)?

But perception is not the only factor. The acoustics of the room is going to determine the correct direction, frequency response and time of arrival of the reflected sound, and finally the result of processing the tracks. Hence the importance of performing an audio calibration system, either automatically (with special microphones that come with the receivers) or done by experts with measuring instruments.

How is the connection of the boxes?

The latest 7.1 channel mid-end receivers with Dolby Pro Logic IIz processing already bring specific speakers outputs for front height channels (vertical) and Wide Front (horizonta). And give the user the possibility to allocate surround back power channels to be used in one of these channel pairs. Therefore, beyond the connection of the speakers, you must enter the SPEAKER SETUP part of the receiver and select the DPL IIz.

Onkio has just launched in the U.S. the TX-NR5010 and NR3010 models able to reproduce in 11.2 channels, but from an optional connected stereo amplifier on one of the optional pre-outs on the rear panel.

Although the 5.1 and 7.1 channel systems master facilities worldwide, the release of nine channels of receivers could be the beginning of a demand for this type of product. With this, it will facilitate the use of more speakers in the system and the total sound immersion to finally get the desired three-dimensional sound.



In the future, experts say, you can find projects of up to 22 channels with speakers placed over our heads. Today, the question we ask is: how many speakers you could install in your living room in order to literally feel surrounded by the movies tracks?


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