Sunday, October 6 2:00 pm – 6:00 pm
SESSION G: MULTICHANNEL SOUND

Chair: Durand Begault, NASA Ames Research Center, Mountain View, CA, USA

G-1 Interchannel Interference at the Listening Position in a Five-Channel Loudspeaker Configuration—Geoff Martin, McGill University, Montreal, Quebec, Canada, and Bang & Olufsen a/s, Struer, Denmark

It is commonly-accepted thinking that the use of a five-channel surround sound reproduction system increases the size of the listening area over that for two-channel stereophonic systems. In actual fact, for many types of program material, the area of this so-called sweet spot is reduced due to interference between the channels at the listener’s ears. This effect is described and analyzed through theoretical evaluation and psychoacoustic listening tests.
Convention Paper 5677

G-2 Breaking and Making the Rules: Sound Design in 6.1—Ambrose Field, University of York, York, UK

It is often colloquially said that there are no rules for the spatialization of multichannel content. This paper seeks to identify creative ways in which the multichannel systems of today and tomorrow can be harnessed to provide aesthetically convincing surround environments. The suitability of production techniques based on Ambisonic methods is re-evaluated for this task, and the discussion focuses on the role of multichannel systems in sound design for presentation in the movie theater.
Convention Paper 5672

G-3 Localization of Lateral Phantom Images in a 5-Channel System With and Without Simulated Early Reflections—Jason Corey, Wieslaw Woszczyk, McGill University, Montreal, Quebec, Canada

Phantom images that rely on interchannel level differences can be produced easily for two-channel stereo. Yet one of the most difficult challenges in production for a five-channel environment is the creation of stable phantom images to the side of the listening position. The addition of simulated early reflection patterns from all five loudspeakers influences the localization of lateral phantom sources. Listening tests were conducted to compare participants’ abilities to localize lateral sources under three conditions: power-panned sources alone, sources with simulated early reflection patterns, and simulated early reflection patterns alone (without direct sound). Our results compare localization error for the three conditions at different locations and suggest that early reflection patterns alone can be sufficient for source localization.
Convention Paper 5673

G-4 The Minimum Number of Loudspeakers and its Arrangement for Reproducing the Spatial Impression of Diffuse Sound Field—Koichiro Hiyama, Setsu Komiyama, Kimio Hamasaki, NHK, Setagaya, Tokyo, Japan

It is important to find out how many loudspeakers are necessary for multichannel sound systems to reproduce the spatial impression of a diffuse sound field. This paper discusses the issue in the case where loudspeakers are placed symmetrically along a concentric circle around the listener and at the same height as the listener’s ear. It becomes clear that the spatial impression of the diffuse sound field can be obtained by only two symmetrical pairs of loudspeakers (that is, four loudspeakers in all). In this arrangement, one pair of loudspeakers should be placed in the frontal area around the listener at an angle of about 60 degrees, and the other pair should be in the rear area with an angle of 120 degrees to 180 degrees.
Convention Paper 5674

G-5 A Fuzzy Cerebellar Model Approach for Synthesizing Multichannel Recordings—Ching-Shun Lin, Chris Kyriakakis, University of Southern California, Los Angeles, CA, USA

New high capacity optical discs and high bandwidth networks provide the capability for delivering multichannel audio. Although there are many one- and two-channel recordings in existence, only a handful of multichannel recordings exist. In this paper we propose a neural network approach that can synthesize microphone signals with the correct acoustical characteristics of specific venues that have been characterized in advance. These signals can be used to generate a multichannel recording with the acoustical characteristics of the original venue. The complex semi-cepstrum technique is employed to extract features from musical signals recorded in a venue and these signals are sent into the fuzzy cerebellar model articulation controller (FCMAC) for training.
Convention Paper 5675

G-6 Investigation of Listener Envelopment in Multichannel Surround Systems—Gilbert A. Soulodre, Michel C. Lavoie, Scott G. Norcross, Communications Research Centre, Ottawa, Ontario, Canada

It is now well understood that listener envelopment (LEV) is an essential component of good concert hall acoustics. An objective measure based on the late-lateral energy has been shown to perform well at predicting LEV. One goal of multichannel surround systems is to improve the re-creation of the concert hall experience in a home listening environment. By varying the amount of late-lateral energy, such systems should allow the perception of LEV to be enhanced and controlled. In this paper the loudspeaker/listening room interactions are shown to limit the range of acoustical conditions that can be re-created. A series of formal subjective tests were conducted to determine if objective measures of late-lateral energy are suitable for predicting LEV in multichannel surround systems.
Convention Paper 5676

G-7 The Significance of Interchannel Correlation, Phase and Amplitude Differences on Multichannel Microphone Techniques—Geoff Martin, McGill University, Montreal, Quebec, Canada, and Bang & Olufsen a/s, Struer, Denmark

There is a measurable interference between correlated signals produced by multiple loudspeakers in a standard five-channel loudspeaker configuration, resulting in an audible comb filter effect. This is due to small individual differences in distances between the ears of the listener and the various loudspeakers. Although this effect is caused by the dimensions and characteristics of the monitoring environment, it can be minimized in the recording process, particularly through the relative placement of microphones and choice of their directional characteristics. In order to analyze this effect, the correlation of microphone signals and their amplitude differences in a recording environment are evaluated using theoretical models. This procedure is applied to coincident and spaced pairs of transducers for direct and reverberant sounds.
Convention Paper 5671

G-8 A Multichannel Surround Audio Format Applying 3D Sound Technology—Myung-Soo Kang, Kyoo-Nyun Kim, University of Ulsan, Ulsan, Korea

As systems employ multichannel audio more and more, it is necessary to consider the surround sound capability in the process of sound recording and playing. This paper presents a structured audio format and its application to design a more efficient surround sound system. Three-dimensional sound technology is used for localization of the sound source. We define the reusable sound object to clarify the audio format. Sound object is a unit of recorded sound samples that can be changed by various effect properties. Filter and 3-D properties are applied to change the sound objects in each track.
Convention Paper 5678