2. Research

Research areas focus on:

3D Audio

  • 3D audio and 3D acoustics recording
  • Room acoustics simulations
  • 3D audio rendering and navigability
  • 3D audio post-production tools
  • 3D audio in live events
  • Exhibition systems for 3D audio
  • Upmix, from stereo or 5.1 content to 3D content

Urban sound prediction and auralization

3D Audio

The 3D Audio technology developed by Barcelona Media represents an evolution of current surround audio technology, being capable of providing 3D audio contents that generate truly immersive experiences. Unlike 5.1 standard surround systems, which cannot cope with sounds from above the listener's horizontal plane, 3D audio allows to:

  • Sounds can be located everywhere around the audience. 3D Audio adds the vertical or z dimension, producing contents to be reproduced in loudspeaker layouts that surround the audience at different heights, so that sounds can be located at all angles.
  • More realism and naturalness. 3D Audio systems provide more immersive, natural, and spectacular experiences. The audience can hear air-planes and spaceships flying above their heads, and bomb explosions and ground shaking below their feet.
  • Reverberation is 3D. Reverberation is a phenomenon we are used to hearing in 3D; when a sound takes place in a church, it propagates through thousands of different paths, arriving to our ears from multiple directions. 3D Audio systems can reproduce reverberation in full fidelity, providing the illusion of being there in a much more powerful manner than planar or 2D systems.
  • Ambient sounds are 3D. 3D Audio is also ideal for reproducing rich ambients, like a scene taking place in a beach with the sea in front, seagulls flying by, vehicles on a road in the back and people having fun. As a result it provides better naturalness, and a soundscape where sounds came from various depths behind the loudspeaker locations.
  • Independence of the exhibition system configuration. 3D Audio technology provides a workflow fully independent of the exhibition setup from the recording stage to the sound reproduction. Layout-blind technologies for production, post-production, encoding and distribution have been developed, as well as decoding technologies capable of optimizing the audio soundtrack to a specific loudspeaker setup, fully exploiting the acoustic capabilities of each particular loudspeaker layout. Thus the entire process of production and post production of 3D audio content is no longer necessary for each individual exhibition setup.

Research areas included in 3D Audio are:

3D Audio and 3D acoustics recording

Research about different recording techniques for capturing 3D sound. In particular, work is based on a physical approach where the aim is to record all needed information about the acoustic field. This way, it is possible to develop recording technologies that do not depend on the exhibition system.

Classical recording techniques for surround sound are based on microphone arrays, which capture the acoustic pressure at different points. The details of the array configuration typically depend strongly on the exhibition system where audio is to be reproduced.

Barcelona Media's approach is based on the recording of other physical magnitudes beyond the acoustic pressure, including the velocity vector of the acoustic field, as well as spherical harmonics of higher order. This technology allows for the capturing of all the parameters required to reproduce the same acoustic field in any given exhibition system.

3D Room acoustics simulation

Development of new algorithms and technologies for the propagation and manipulation of sound in virtual environments:

   

  • Geometric algorithms for sound propagation: development of algorithms for sound rendering – sound adaptation to a given 3D model – based on the geometric approximation to the wave equation. At present, Barcelona Media researchers focus on ray tracing algorithms to compute the acoustics on a given environment, based on the projection and continuation of imaginary sound lines from the receptor to the various sound sources present in the scene. Video of ray tracing: http://comunicacio.barcelonamedia.org/video_raytracing.mpg
  • Numerical methods: development of algorithms for the exact solution of the wave equation. In particular, research focuses on the so-called finite-differences algorithms, which are widely used in many other fields of science, and specially in Electromagnetism (for example, in the study of antenna distribution for optimal signal transmission to mobile receptors).

Video of FDTD: http://comunicacio.barcelonamedia.org/video_FDTD.avi

3D audio rendering and navigability

Research in audio post-production and multimedia applications for the generation of 3D sound scenes, which can be reproduced and navigated, in the sense that the acoustic scene varies depending on the position of the listener.

The room acoustics of the spaces in the scene can be reverberations captured from real existing spaces or can be recreated from 3D virtual environments using room acoustics simulation technology and ray-tracing algorithms.

The Audio group also develops technology for positioning and moving sound sources in a 3D environment, providing these sound sources with the necessary characteristics to form a realistic soundscape.

3D audio post-production tools

Research in technologies for authoring, monitoring and encoding 3D audio by making use of existing Digital Audio Workstations extended with plugins and possibly external 3D modelling tools.

The group has also been involved in research of deconvolution algorithms: development of new algorithms to de-reverberation (subtraction of reverberation or echoes) in recorded signals.

Video of deconvolution: http://comunicacio.barcelonamedia.org/Video_deco_v2.mpg

3D audio in live events

Research to expand 3D Audio technology to broadcasting and streaming of live events.

  • Mixed recording and processing techniques to record audio of live events: sports, concerts, teleconferences.
  • Technology and tools for live reconstruction and edition of the 3D scene
  • Streaming 3D audio technology
  • Technology to syncronize 3D audio with video in reception.

Exhibition systems for 3D audio

Research in different technologies focused on 3D Audio exhibition:

  • Automatic exhibition loudspeakers layout detection
  • Automatic equalization of loudspeakers and the acoustics of the showroom
  • 3D Audio decoding technology optimizing for each particular loudspeaker layout and detected showroom acoustic characteristics: research in algorithms for the exhibition of audio in multi-loudspeakers systems, from the popular 5.1 system to innovative layouts with loudspeakers at different heights.
  • 3D Audio decoding to headphones by binaural technology capable of providing a full 3D perception using simple headphones.

 

Upmix technology

Research in upmixing technology for inferring new channels from the information present in a stereo or 5.1 audio source, converting stereo or 5.1 content to 3D content.

Beyond 3D Audio, the audio group also does research in:

Urban sound prediction and auralization

The objective of this research is to obtain the curve of acoustic attenuation of sound propagation in outdoor environments using standard European models. In particular the group is working on:

  • Calculation of the acoustic impact of the different sound sources present in an environment based on a simplified 3D model of the urban environment.
  • Navigation. Calculation of sound pressure level in a high density of points in the environment, so as to allow navigation through the environment providing data from the acoustic impact at every point.
  • Auralitzation. Capability to playback, given the existing sound sources, the sound spread in the environment.