Multi-channel audio has become mainstream and vendors have created many types of basic and more sophisticated technologies including wireless surround sound speakers, virtual surround sound to simplify the installation of home theater kits. I will review the most recent trends to determine which devices actually work. I will also give some guidance for selecting the ideal components.

Traditionally, installing a TV would be quick because they would already come with built-in stereo speakers. This, however, has all changed with multi-channel sound. These days external speakers are used to create a surround sound effect. As the traditional 5.1 format requires 6 speakers: a front center, two front side speakers, two rear speaker and a subwoofer, the more modern 7.1 format adds two additional side speakers.

As a result setting up a home theater has turn out to be rather complex and long speaker wire runs are often undesirable for aesthetic reasons. Component vendors have designed several technologies to simplify the installation.

One approach is minimizing the number of loudspeakers by creating virtual loudspeakers. This technique applies signal processing to the sound and adds phase shifts and cues to the audio which would usually be broadcast through the remote speaker. The audio is then sent by the front speakers along with the front speaker sound components. The signal processing is modeled after the human hearing. It uses the knowledge about how the human ear can determine the source of sound. The signal processing has an effect that will trick the listener into assuming that the audio is originating from a different location.

The benefit of this technology is that only a couple of loudspeakers are required and no long speaker cord has to be run all through the viewing environment. The disadvantage however is that each person will process audio in a different way as a result of the different form of each human ear. The signal processing of these virtual surround systems is based on a standard model which was calculated with a standard ear. However, virtual surround will not function equally well for each person.

An alternative option for eliminating long speaker wire runs is to use wireless surround sound devices or wireless loudspeakers. A wireless product consists of a transmitter and one or a number of wireless amplifiers. The transmitter connects to the source. The wireless amplifiers connect to the remote loudspeakers. The transmitter will normally have amplified speaker inputs in addition to line-level inputs and have a volume control to adjust it to the source audio level.

Whilst some wireless speaker systems have a wireless amplifier that connects to two speakers, other devices offer separate wireless amplifiers for every speaker. Entry-level wireless products use FM transmission or audio compression that will degrade the audio quality to some extent. More sophisticated wireless systems make use of uncompressed digital audio transmission. Ensure that you pick a wireless system with a low audio latency, at most a few milliseconds. This will guarantee that the sound from all loudspeakers, including the non-wireless speakers, is in sync. Low latency is also vital for good sync with the video. If the latency is larger than 10 ms then there will be an echo effect which will degrade the surround sound. Many wireless products operate in the 900 MHz and 2.4 GHz frequency bands. A number of products use the less crowded 5.8 GHz frequency band and therefore have less competition from other wireless products.

A third technology utilizes side-reflecting speakers. This method is called sound bars. In this case the audio for the remote loudspeakers will be broadcast by separate speakers positioned at the front at an angle and reflected by walls as to seem to be originating from besides or behind the viewer. This method works best in a square room with minimal interior design and obstacles. It will not function well in many real-world scenarios with different room shapes however.