Medical physics

Johannes Nix


Johannes Nix
Medical Physics Section
Carl von Ossietzky-Universität Oldenburg
D-26111 Oldenburg

e-mail: (Note: substitute _Π_ (Pi) with @, please)
phone: +49 441 798-3091
fax:     +49 441 798-3902
office location: W2-2-256

Academic CV

  • 1987 - 1990 RWTH Aachen, prediploma in Physics
  • 1990 - 1991 Phillips Universität Marburg, studying nonlinear dynamics, theoretical ecology, political science and philosophy
  • 1991 - 1993 Carl-von-Ossietzky Universität Oldenburg
  • 1993 - 1994 Universidad de los Andes, Bogotá, Columbia; Master course about mechanical engineering, numerical models of small wind power plants
  • 1994 - 1998 Carl von Ossietzky Universität Oldenburg, Diploma
  • 1998 - 2001 Scholarship at "Graduiertenkolleg Psychoakusik" (Oldenburg Graduate School Psychoacoustics)
  • 2002 - 2003 Grant from "International graduate school of neursosensoric science and systems"

Research Interests

  • Statistical description of speech
  • Models of auditory scene analysis and "binding" auf auditory features
  • Robust noise suppression for future hearing aids
  • Numerical methods and efficient algorithms in speech processing
  • Methods for algorithm research in modern environments; especially real-time processing, parallel processing and multitasking / multithreading on portable hardware.
  • Emotional speech processing, e.g. recognition of emotions by prosody.


    PhD Thesis:

    Nix, J. (2005b), Localization and Separation of Concurrent Talkers Based on Principles of Auditory Scene Analysis and Multi-Dimensional Statistical Methods, Ph.D. thesis, Universität Oldenburg.

    Download of Thesis:

    Electronic version (available as PDF document or as gzipped' postscript, optimized for two-side printing on several paper formats):

    Audio demonstrations (section 3.3.3, experiment #6):

    Nix, J. (2005a), "Audio examples for sound source demixing controlled by Bayesian sound localization" Audio demonstration of physiologically inspired signal processing: Use of Noise-Robust Sound Localization for the Separation of Voices.

Journal Articles

Nix, J., and Hohmann, V. (2006), "Sound source localization in real sound fields based on empirical statistics of interaural parameters," J. Acoust. Soc. Am., 119(1):463–479. DOI:10.1121/1.2139619
Self-archived online version: PDF or PS.GZ
Copyright notice: Copyright (2006) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. AIP online version available here.

Hohmann, V., Nix, J., Grimm, G., and Wittkop, T. (2002d), "Cocktail party processing based on interaural parameters," Acta acustica united with acustica, 88(Suppl. 1):1–6.

Nix, J., and Hohmann, V. (2005), "Combined estimation of spectral envelopes and sound source direction of concurrent voices by multidimensional statistical filtering," In preparation.

Book Chapters

Nix, J., and Hohmann, V. (1999), "Statistics of binaural parameters and localization in noise," in T. Dau, V. Hohmann, and B. Kollmeier (editors), "Psychophysics, Physiology and Models of Hearing," (World Scientific Publishing Co., Singapore), pp. 263–266.
Download: GZ ZIP BZ2

Conference Contributions

Hohmann, V., Albani, S., and Nix, J. (1999), "ApplLokaication of localization models to noise suppression in hearing aids," ACUSTICA - acta acustica, 85:S225, talk presented at the 137th meeting of the Acoustical Society of America joint with Forum Acusticum 1999 in Berlin. See also JASA 105, 1151.

Hohmann, V., Nix, J., Grimm, G., and Wittkop, T. (2002a), "Binaural noise reduction for hearing aid," in "Proc. International Conference on Acoustics, Speech, and Signal Processing (ICASSP)," (IEEE), volume 4, pp. 4000–4003.

Hohmann, V., Nix, J., Grimm, G., and Wittkop, T. (2002b), "Binaural noise reduction for hearing aids," in "Proceedings of the ICASSP," volume IV, pp. 4000–4003.

Hohmann, V., Nix, J., Grimm, G., and Wittkop, T. (2002c"), "Cocktail party processing based on interaural parameters," in "3rd European Congress on Acoustics - Forum Acusticum 2002," .

Meyer, R., Nix, J., and Hohmann, V. (2005), "Sequentielle Monte-Carlo-Verfahren zur Grundfrequenzerkennung überlagerter realer und synthetischer Vokale," in "Fortschritte der Akustik- DAGA'2005," (DEGA Deutsche Gesellschaft für Akustik, Oldenburg).

Nix, J., and Hohmann, V. (2000), "Robuste Lokalisation im Störgeräusch auf der Basis statistischer Referenzen, "in A. Sill (editor), "Fortschritte der Akustik – DAGA'2000," pp. 384–385.
Download: GZ ZIP BZ2

Nix, J., and Hohmann, V. (2001a), "Enhancing sound sources by use of spatial cues," in P. Dalsgaard (editor), "Proceedings of the Eurospeech 2001 Workshop on Consistent and Reliable Acoustical Cues (CRAC)," (International Speech Communication Association), pp. 1–4,

Nix, J., and Hohmann, V. (2001b), "Verallgemeinerbarkeit von Referenzen in einem Lokalisationsmodell und Auswirkungen auf Robustheit und Generalisierungsvermögen," in O. von Estorff (editor), "Fortschritte der Akustik- DAGA'2001," (DEGA (Deutsche Gesellschaft für Akustik e. V.), Oldenburg).

Nix, J., Kleinschmidt, M., and Hohmann, V. (2003a), "Computational auditory scene analysis by using statistics of high-dimensional speech dynamics and sound source direction," in "Proceedings of the 8th European Conference on Speech Communication and Technology (Eurospeech)," (ICSA International Speech Communication Association, Bonn, Germany), pp. 1441–1444.

Nix, J., Kleinschmidt, M., and Hohmann, V. (2003b), "Computational scene analysis of cocktail-party situations based on sequential Monte Carlo methods," in "Proceedings of the Thirty-Seventh Asilomar Conference on Signals, Systems, \& Computers," (IEEE Signal Processing Society), volume 1, pp. 735 –739.

  • Nix, J. and Hohmann, V. (1998).
    Lokalisation im Störgeräusch auf der Basis der Statistik binauraler Parameter}.
    In A. Sill (ed.),"Fortschritte der Akustik- DAGA'1998, DEGA (Deutsche Gesellschaft für Akustik e. V.), Oldenburg. 474-475.
    Download: GZ ZIP BZ2

    Minor Theses

      Physics of renewable Energies

      • Studienarbeit: Forschung und Entwicklung von Windpumpen in Kolumbien und Überblick über den Stand der Entwicklung. Supervised by Dr. Alvaro Pinilla, Universidad de los Andes, and Prof. Wolfgang Schmidt, Universität Oldenburg.
        Download: GZ ZIP BZ2

        (I should add some photos from Colombia here, will do that later)

      Political Sciences

      • Homework in Political Sciences: Silke Kreusel, Johannes Nix Umweltbewegungen in Lateinamerika am Beispiel des Chocó (supervised by Prof. Fernando Mires)
        Download: GZ ZIP BZ2

      Acoustics and Signal Processing

      • Diploma thesis: Lokalisation und Störgeräuschunterdrückung in Cocktail-Party-Situationen auf der Basis der Statistik binauraler Parameter

    Open Source Software

      Some time ago, I created audio bindings for Numerical Python, which accessed the Linux ALSA library, and made real-time audio processing within Python possible. A very early version of it could be provided as open source Python module under the name rtaudio. This package is severely out-dated; if you are interested in developing Open-Source (GPL licensed) library modules for the Python language with bindings between the new NumPy vector library, the JACK audio server, and the current version of the ALSA (Advanced Linux Sound Architecture) library, please contact me by mail.