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[English] SPACEMAKER: the Space Maker

Auralization: The Importance of an Impulse Response Data Library

Reverberation is an audible effect heard every day as a result of the interaction of sound with the surrounding environment.

OpenAIR

Openair is an Internet reverb library, which aims to provide an online resource system of impulse response-acoustic response and auralization data.

A database of acoustic data from different parts of the world. The project calls for contributions from users to the library, which is fully licensed under the Creative Commons license.

The Importance of an Impulse Response (IR) Data Library

Such a library is extremely useful for researchers who need to quickly compare impulse responses using different approaches, for video game audio developers who want to recreate the acoustic environment of a specific building, or for composers who want to consider how the reverberation of a location affects their works.

Video game developers are turning to convolution reverb effects to provide a fully immersive and realistic audio experience for the user. This requires impulse response data to be recorded or artificially generated and to fit perfectly into the game environment.

The research fields related to what is called auralization are multidisciplinary and require knowledge of room acoustics, acoustic physics, digital signal processing, real time systems and psychoacoustics.

Auralization

Auralization is useful to analyze spaces that are in the process of being designed (such as architectural or virtual spaces) or in spaces that already exist. It allows us to auditively check the acoustic quality of those spaces, simulating the acoustic effects that may occur and providing the researcher with exact parameters for their possible correction, that is, it gives us the possibility to experience the sound sensation of being in a particular environment whether it is real or non-existent.

There are different systems of auralization, one of them is the system by convulsion, these systems are based on the previous knowledge of what is called impulse response h(t).

The impulse response h(t) at any point in a room contains all the information about the sound field at that point. This impulse response h(t) depends mainly on the shape, the materials used and the finishing of the room, as well as the position of the sound source and the receiver. With the knowledge of the impulse response h(t) we obtain the so-called monaural auralization. However, in order to make the auralisation of space as real as possible, two fundamental pieces of information are needed:

-the “impulse response” of the right ear of the receiver hr (t)
-the “impulse response” of the left ear of the hl receiver (t)
The knowledge of both answers allows us to obtain the so-called stereo or binaural auralization.

Virtual Sound Environments

In recent years, the development of tools for acoustic prediction of the room and auralization techniques, made great progress allowing the simulation of virtual sound environments in real time.

Generating accurate virtual sound environments remains much more complex than the task of creating images. One of the reasons is the difficulty computers are having in rendering 3D audio in real time. Models are required that describe the directional patterns of the sound sources, as well as the positioning of the receiver at all times, analysis of diffraction, dispersion and transmission of the sound.

Many of the virtual reality systems aim to address sensory perceptions from sound. It is known that visual perception is significantly increased with the accompaniment of sound stimuli. Auditory information helps to give spatial meaning to visual information, significantly increasing the sense of real presence in the simulated scene.

The quality of a virtual reality system can be evaluated by the degree of immersion of the user, which improves with the number of simulated and coherent stimuli provided by a high level of interactivity by the user.

This becomes especially challenging within dynamic environments where the user is allowed to move freely in the three dimensions and interact with the sound sources and modify the surrounding space where a change in the geometry of the scene significantly affects the entire auralization chain.

In this new era for virtual reality it is required to work together in the field of psychoacoustics to generate a sound that has the optimal balance between the accuracy of the simulation and the computing power available in computers.

The ultimate meaning of a virtual world is to dissolve the limitations of the world to which we are anchored in such a way that we can carry the anchor, not to wander aimlessly and senselessly, but to explore and anchor ourselves in ever new places and, perhaps, find our way back to the experience of the most primitive and powerful possibility lodged in the question proposed by Leibniz:
why does being exist instead of nothing?

The Metaphysics of Virtual Reality, Michael Heim

Article updated December 12, 2019


Author: Sol Rezza
Editor | Corrector: Franco Falistoco
@ 2019

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