2. Research

The main research topics are:

  • Surround sound recording 
  • Audio rendering in virtual environments 
  • 3D audio exhibition systems

 

Surround sound 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 playback 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 playbacked.

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.

 

Audio rendering in virtual environments

 

Research in audio post-production for various multimedia applications. Development of new algorithms and technologies for the propagation and manipulation of sound in virtual environments. Ray Tracing

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

 

Deconvolution algorithms: research on new algorithms to de-reverberation (subtraction of reverberation or echoes) in recorded signals.

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

 

CLAM (C++ Library for Audio and Music): set up of an open source platform for research and development in the fields of audio and music.

 

3D audio exhibition systems

 

Research in different systems for the playback of 3D audio given the pressure and velocities of the acoustic field.

Binaural Technology: capable of providing a full 3D perception using simple headphones.

Ambisonics Technology: based on capturing of other magnitudes of the acoustic field beyond the pressure signal.

3D Exhibition systems: research in algorithms for audio playback in multi-loudspeakers setups, from the popular surround 5.1, to more innovative configurations including loudspeakers at different heights.