Sound Field Synthesis Toolbox 0.2.1 released

Posted on 18. June 2012 by Hagen Wierstorf

A new version of the Sound Field Synthesis (SFS) Toolbox is available.
Highlights of this release are:

  • simulation of monochromatic wave fields for 2.5D NFCHOA (see the figure below)
  • simulation of monochromatic wave fields for 2.5D SDM
  • NFCHOA simulations now also work under Octave

In addition we fixed some bugs and made some minor changes, especially

  • fixed direction of plane waves and point sources for NFCHOA time domain simulations
  • changed syntax for wave_field_* and driving_* functions: 
    xs,f,src => xs,src,f
xs,L,src => xs,src,L
xs,L,f,src => xs,src,f,L

The sources of the new version can be downloaded on the usual site.

monochromatic 2.5D NFCHOA wave field

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Additional material for the paper “On the implementation of Range Extrapolation of Head-Related Impulse Responses by Virtual Sound Field Synthesis using Integer Delays”

Posted on 18. June 2012 by Sascha Spors

This post contains additional material for the paper

Sascha Spors and Hagen Wierstorf. On the Implementation of Range Extrapolation of Head-Related Impulse Responses by Virtual Sound Field Synthesis using Integer Delays. In German Annual Conference on Acoustics (DAGA), March 2012.

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Sound Field Synthesis Toolbox 0.2 released

Posted on 9. May 2012 by Hagen Wierstorf

We are happy to announce the first public and open source release of our Sound Field Synthesis (SFS) Toolbox. It is a toolbox for Matlab/Octave to numerical simulate different SFS methods like Wave Field Synthesis (WFS) or higher order Ambisonics (HOA). It provides a variety of functions to reach mono-frequent and spatio-temporal impulse responses for different array geometries and driving functions.

You can find the sources and documentation on the corresponding SFS Toolbox site.

Note that there are two bugs in the current version, and one of them will prevent you from plotting the results. Have a look at the corresponding wiki page how to fix this.

To demonstrate some of the features of the toolbox, below an image of a mono-frequent plane wave synthesized using WFS and a linear loudspeaker array is shown. The different colors of the speakers at the ends of the array visualize the applied tapering window.

plane wave, synthesized using WFS and a linear loudspeaker array

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Listening examples for the paper “Evaluation of perceptual properties of phase-mode beamforming in the context of data-based binaural synthesis” presented at ISCCSP 2012

Posted on 2. May 2012 by Sascha Spors

We have presented a paper at the 5th International Symposium on Communications, Control, and Signal Processing. It discusses the influence of spatial bandlimitation in modal beamforming when used as plane wave decomposition for binaural synthesis. Besides the instrumental measures given in the paper/presentation you can also download a series of listening examples. The samples have been computed for the parameters described in the paper. The maximum order N of the spherical harmonics expansion has been varied, as well as the head rotation (incidence angle of the virtual source). As source material noise bursts, speech and castanets have been used. The examples are provided as binaural sound files optimized for the AKG K-601 headphone. The file names encode the conditions and incidence angle.

Download the listening examples by following this link

 

The full reference to the paper is

S. Spors and H. Wierstorf. Evaluation of perceptual properties of phase-mode beamforming in the context of data-based binaural synthesis. In IEEE-EURASIP International Symposium on Control, Communications, and Signal Processing, May 2012.

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Listening examples for the paper “A comparison of phase-mode versus delay-and-sum beamforming in the context of data-based binaural synthesis”

Posted on 28. April 2012 by Sascha Spors

At the 132nd Convention of the Audio Engineering Society we presented the paper

S. Spors, H. Wierstorf, and M. Geier. Comparison of modal versus delay-and-sum beamforming in the context of data-based binaural synthesis. In 132th AES Convention. Audio Engineering Society (AES), April 2012.

The presentation slides are available here.

This post provides listening examples for the comparison of modal (MB) and delay-and-sum (DSB) beamforming when used as plane wave decomposition for binaural synthesis. The stimuli have been computed as described in the paper for spatially continuous and sampled spherical microphone arrays. Additionally for modal beamforming the maximum order of the spherical harmonics has been varied in the spatially continuous case. As source material noise bursts, speech and castanets have been used. The examples are provided for various incidence angles, as stereo sound files optimized for the AKG K-601 headphone. The file names encode the conditions and incidence angle.

Download the samples for

by following the links.

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First Release of the Audio Processing Framework (APF)

Posted on 10. April 2012 by matthias.geier

We collected some generic C++ code which we programmed over the last few years and bundled it into the so-called Audio Processing Framework (APF).

That’s the website: http://tu-berlin.de/?apf

More details (including downloads and Doxygen documentation) are here: http://dev.qu.tu-berlin.de/projects/apf/wiki

It will be presented at the Linux Audio Conference (LAC) in a few days.

Here’s the paper, feel free to cite:

Matthias Geier, Torben Hohn and Sascha Spors: “An Open Source C++ Framework for Multithreaded Realtime Multichannel Audio Applications”, Linux Audio Conference, Stanford, CA, USA, April 2012.

EDIT (July 2013): The APF now has a new home: http://AudioProcessingFramework.github.io

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Release 0.3.3 of the SoundScape Renderer

Posted on 7. February 2012 by Sascha Spors

We are proud to announce a new release of the SoundScape Renderer (SSR). The new release 0.3.3 (Harpsichord) can be downloaded here. This release contains a number of bug-fixes and extensions. Major improvements are

  • fixed a bug in the WFS renderer which caused audible artefacts (klicks)
  • support for our Razor-based head-tracker
  • support for OS X 10.7

We would like to thank all contributors who reported bugs or even provided bug-fixes. We encurage all users to send bugs, usage reports and feature requests to SoundScapeRenderer@telekom.de. You can also send us your (example) scenes or content you have produced with the SSR. Some user content can already be found here.

The SSR development team.

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New Release of SOFiA available

Posted on 22. December 2011 by Sascha Spors

A new release of the Sound Field Analysis Toolbox (SOFiA) is available! This release includes a number of bugfixes and extensions:

  • various bug-fixes and optimizations
  • new sampled wave generator that handels various array configurations (open/dual-open/rigid spheres, pressure/pressure-gradient microphones) for a plane wave/point source as incident sound field
  • native support for Legendre and Lebedev grids

SOFiA can be downloaded here http://code.google.com/p/sofia-toolbox/.

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Book on Sound Field Synthesis

Posted on 5. December 2011 by Jens Ahrens

I proudly announce that some time ago, I submitted the manuscript of a monography on sound field synthesis to Springer who will publish it under the title Analytic Methods of Sound Field Synthesis in spring 2012. You can find the official announcement here.
The book is not only a mere copy-and-paste of our papers. All our own work has been significantly enhanced in didactical terms and, of course, all relevant works of other authors and a considerable amount of previously unpublished material are included. Besides the physical fundamentals and spatial discretization (e.g., spatial aliasing), extensive discussions of various applications of sound field synthesis such as moving virtual sound sources, focused virtual sound sources, etc. and a variety of practical aspects are discussed. I have also put some effort in clarifying the relationship between Ambisonics and Wave Field Synthesis.

MATLAB/Octave scripts for all simulations contained in the book will be provided at http://www.soundfieldsynthesis.org.

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DIY low-cost head-tracker

Posted on 30. November 2011 by Sascha Spors

We have published a tutorial and firmware which allows to put together a low-cost Attitude and Heading Reference System (AHRS) that can be used as a head-tracker for virtual acoustics. A wired version of the tracker (connected via USB), as well as a wireless version (using Bluetooth) can be realized quite simple using comercially available hardware. The tracker is based on the Arduino-compatible “9DOF Razor IMU” board by SparkFun, which contains a 3-axis gyroscope/accelerometer/magnetometer and a microcontroller to do the sensor fusion.

Open source AHRS / head-tracking using SparkFun 9DOF Razor IMU (via USB or Bluetooth) from Spatial Audio Research on Vimeo.

The next release of the SoundScape Renderer (SSR) will support the tracker.

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