Surround Sound System Research Articles

Surround Sound Systems and the Audio Amplifier

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The Visualization Center at Scripps Institution of Oceanography: Education and Outreach

Since opening in March 2002, the Visualization Center at Scripps has had more than 2,500 visitors, of which ∼500 were education- and outreach-related. Based upon follow-up requests and referrals, we expect these numbers to grow. The center's state-of-the-art visualization technology projects high-resolution, multidimensional images onto a 120° curved Panoram® floor-to-ceiling screen (8′6″ by 28′4″) that immerses viewers in a virtual environment (Figure 1). The center is ideal for presenting and manipulating very large data sets to groups of up to 50 people, and the system is equipped with transmitters and LCD shutter glasses that allow stereographic 3D viewing of high-resolution data sets through a set of specialized eyeglasses (Figure 2). The lenses in the glasses flicker synchronously with the computer images at 48 flames per second, per eye, thus producing a stereo or 3D effect. Figure 1. ▴ A group of visitors in the Visualization Center at Scripps view the topography of Mars. Multiple video streams can be simultaneously displayed, including the SGI® megadesktop, S-VHS video, DVD video, and video from a laptop computer; the user can quickly toggle between these various platforms (Kent et al., 2002). Similarly, the five-channel surround-sound audio system can be integrated through several inputs, allowing for numerous video and audio combinations. For instance, one third of the screen can display S-VHS video of damaging earthquakes, while the remaining portion of the screen can show an interactive underground 3D flight through seismicity in the regions presented in the video. Alternatively, the audio surround-sound system can be set to produce sounds of various synthetically generated earthquakes (http://quake.wr.usgs.gov/info/listen/allsounds.htmt), while the corresponding seismicity, topography, and seismic station locations and telemetry paths are juxtaposed on the screen with the associated seismic waves. Figure 2. ▴ Visitors to the Visualization Center at Scripps use specially designed 3D glasses to view high-resolution stereo images of the …

Surround sound loudspeaker system

The generation of skewed hypercardioid sound energy fields (in polar diagrams) from right front and left front "surround" loudspeakers with the principal nulls directed at the expected listener location produces the effect of sidewall and rearwall loudspeakers in a home theater setting without any actual sidewall or rearwall loudspeakers. The effect is enhanced by secondary nulls that are directed so as to "reflect" off the front wall of the room toward the expected listener location. Each surround loudspeaker contains an antiphase driver and circuitry including a delay network that powers the drivers to create the skewed hypercardioid sound energy field. The invention is independent of electrical mixing and interaction of two or more input channels. Rather the channels are assumed to be independent and the invention concerns the unique directional sound energy radiation pattern generated from each channel considered independently. An important feature of the skewed hypercardioid sound energy field according to the invention is the insensitivity of the principal null direction to frequency over a range of 120 H z to 4 kH z . Also important is a surround sound effect more pronounced in miniature (close range) speaker configurations because the energy gradient between the right and left ears is steeper with the skewed hypercardioid at close range. The invention provides a generalized method of handling direct and reflected sound in an enclosed listening space, since the parameters are variable with delay in the circuitry, the angular relationship of the drivers in the loudspeaker cabinet and the shape of the cabinet. In some listening configurations only the surround loudspeakers are necessary for superior sound reproduction.

Ambisonic reproduction of directionality in surround-sound systems

In both the technology and the aesthetics of extending high fidelity reproduction to surround-sound, reproduction of natural ambience is crucial. The ‘quadraphonic’ attempt to reproduce four stereo-blended tracks, derived from multi-microphone mix-down, cannot provide this. Complete spherical directionality can however be encoded on to a minimum of two audio channels to produce acoustically acceptable surround-sound systems. Limitations are set both by the number of available loudspeakers and by the number of channels.