Page 46 - Spring2020

Michael Vorländer
Address:
Institute of Technical Acoustics RWTH Aachen University Kopernikusstrasse 5 52074 Aachen Germany
Email:
mvo@akustik.rwth-aachen.de
Are Virtual Sounds Real?
Are virtual sounds real? Yes, they are if the computer simulation of the sound is accurate and fast.
We have enough real sounds around us. Why create virtual sounds?
Introduction
Imagine if we could listen in the future, such as music in future concert halls. Imagine if we could transport ourselves into the past, as when jazz was born in New Orleans.
A marching band in the Mardi Gras in New Orleans (LA) is a very dynamic acoustic situation that includes many moving instruments, a great deal of directional infor- mation, and many other features that create multidimensional impressions, a good mood (or annoyance), and a clear sense of this event as a vivid music festival (see bit.ly/33GBjy8). This video, which was recorded in 2017, is, in a way, an historic document, with visual and auditory information captured and stored for future replay. Although the video provides some sense of the Mardi Gras, wouldn’t it be fantastic if we could be “inside” the event in a three-dimensional (3-D) immersive environment, which is quite a different experience from watching the event in the video, on TV, or as an “outside” observer?
It would also be quite amazing if we could place Louis Armstrong in one of the bands! If this works, why not change the location of the band to Bourbon Street in 1920? And then we could rather re-create this scene in full 3-D (Figure 1, right). With an appropriate acoustic component in virtual reality (VR), we can transform the historic scenario (see bit.ly/2X5yiVV) into an immersive 3-D experience with
“real” sound instead of a silent movie with added music.
Of course, to get the immersive 3-D experience, we need more than just the record- ing of the total sound at the observer’s (camera/microphone) position. Instead, we must start with capturing data from all of the instruments, one by one, and then
Figure 1. See and hear the difference. Left: watching Mardi Gras on a TV set; right: being literally “inside” Mardi Gras, in a virtual acoustic environment. Original photo of marching band by Prayitno, used under the Creative Commons license with attribution (CC BY 2.0).
46 | Acoustics Today | Spring 2020 | volume 16, issue 1 ©2020 Acoustical Society of America. All rights reserved. https://doi.org/10.1121/AT.2020.16.1.46