• automatic speech recognition: acoustic modeling, discriminative training, linear transformations, maximum entropy modeling
• information retrieval: spoken document retrieval, probabilistic models

Publications

2005

• G. Heigold, W. Macherey, R. Schlüter, H. Ney: Minimum Exact Word Error Training. In Automatic Speech Recognition and Understanding Workshop (ASRU 2005), Cancun, Mexico, November 27 - December 1, 2005.   ,

• W. Macherey, L. Haferkamp, R. Schlüter, H. Ney: Investigations on Error Minimizing Training Criteria for Discriminative Training in Automatic Speech Recognition. In Proceedings of the 9th European Conference on Speech Communication and Technology (Interspeech 2005), Lisboa, Portugal, pp. 2133-2136, September 2005.   ,   slides  

• W. Macherey, R. Schlüter, and H. Ney: Discriminative Training with Tied Covariance Matrices. In Proceedings of the 8th International Conference on Spoken Language Processing (ICSLP 2004), Jeju Island, Korea, Vol. 1, pp. 681-684, October 2004.   

• D. Keysers, W. Macherey, H. Ney, and J. Dahmen: Adaptation in Statistical Pattern Recognition Using Tangent Vectors. In IEEE Transactions on Pattern Analysis and Machine Intelligence, Vol. 26, No. 2, pp. 269-274, February 2004.   

• W. Macherey, H. Ney: A Comparative Study on Maximum Entropy and Discriminative Training for Acoustic Modeling in Automatic Speech Recognition. In Proc. European Conference on Speech Communication and Technology, Vol 1, pp. 493-496, Geneva, Switzerland, September 2003.   

• W. Macherey, J. Viechtbauer, H. Ney: Probabilistic Aspects in Spoken Document Retrieval. In EURASIP Journal on Applied Signal Processing, Special issue on "Unstructured Information Management from Multimedia Data Sources", Vol. 2003, No. 2, pp. 115-127, February 2003.   

• W. Macherey, J. Viechtbauer, H. Ney. "Probabilistic Retrieval Based On Document Representations", in Proc. Int. Conf. on Spoken Language Processing, Denver, CO, Vol. 3, pp. 1481-1484, September 2002.   

• W. Macherey, H. Ney. "Towards Automatic Corpus Preparation for a German Broadcast News Transcription System", in Proc. IEEE Int. Conf. on Acoustics, Speech, and Signal Processing, Orlando, FL, Vol. 1, pp. 733-736, May 2002.   

• D. Keysers, W. Macherey, J. Dahmen, H. Ney. "Learning of Variability for Invariant Statistical Pattern Recognition". In ECML 2001, 12th European Conference on Machine Learning, Freiburg, Germany, Vol. 2167, pp. 263-275, Lecture Notes in Computer Science, Springer, September 2001.   

• W. Macherey, D. Keysers, J. Dahmen, H. Ney. "Improving Automatic Speech Recognition Using Tangent Distance". In Proc. European Conference on Speech Communication and Technology, Aalborg, Denmark, Vol. 3, pp. 1825-1828, September 2001.   

• R. Schlüter, W. Macherey, B. Müller, H. Ney. "Comparison of Discriminative Training Criteria and Optimization Methods for Speech Recognition". In Speech Communication. Vol. 34, pp. 287-310, May 2001. 
  EURASIP Best Paper Award

• R. Schlüter, W. Macherey, B. Müller, H. Ney. "A Combined Maximum Mutual Information and Maximum Likelihood Approach for Mixture Density Splitting". In Proc. Sixth European Conference on Speech Communication and Technology, Vol. 4, pp. 1715-1718, Budapest, Hungary, September 1999.    

• H. Ney, W. Macherey, S. Molau, A. Sixtus. "Von der Spracherkennung zum Spoken Document Retrieval". Abschlußworkshop 'Die virtuelle Wissensfabrik', 20 pages, St. Augustin/Bonn, Germany, September 1999. 

• W. Macherey, H. Ney. "Audiosuche: Information Retrieval in multimedialen Datenbanken", in Proc. Workshop "Die virtuelle Wissensfabrik", St. Augustin, Germany, 12 pages, September 1999.   

• W. Macherey. "Implementierung und Vergleich diskriminativer Verfahren für Spracherkennung bei kleinem Vokabular" (Implementation and Comparison of Discriminative Training Methods for Automatic Speech Recognition), Diploma thesis, Lehrstuhl für Informatik VI, RWTH Aachen, Aachen, November 1998.   

• R. Schlüter, W. Macherey. "Comparison of discriminative training criteria". Proc. Int. Conf. Acoustics, Speech and Signal Process. 1998 , Seattle, WA, Vol. 1, pp. 493-496, May 1998.   

• R. Schlüter, W. Macherey, S. Kanthak, H. Ney, L. Welling. "Comparison of optimization methods for discriminative training criteria". Proc. 1997 Europ. Conf. on Speech Communication and Technology , Rhodes, Greece, Vol. 1, pp. 15-18, September 1997.   

Technical Innovations

• a new probabilistic retrieval metric based on document representations (in close collaboration with J. Viechtbauer) (2002)
• tangent distance for automatic speech recognition (2001)
• a hybrid approach for a combined ML/MMI splitting criterion (1998)

Talks

• W. Macherey. Discriminative Training for LVCSR. PhD seminar at Lehrstuhl für Informatik VI, RWTH Aachen, July 08, 2003
• W. Macherey. Discriminative Training in ASR - State of the Art. PhD seminar at Lehrstuhl für Informatik VI, RWTH Aachen, January 20, 2003
• W. Macherey. Investigations on Linear Feature Space Transformations. PhD seminar at Lehrstuhl für Informatik VI, RWTH Aachen, December 9, 2002
• W. Macherey. Investigations on Linear Feature Space Transformations. IBM T.J. Watson Research Center, Yorktown Heights, NY, August, 2002
• W. Macherey. Introduction to Discriminative Training in ASR. Study group ASR at Lehrstuhl für Informatik VI, RWTH Aachen, July 4, 2002
• W. Macherey. Automatic Corpus Preparation for Broadcast News with Application to SDR. PhD seminar at Lehrstuhl für Informatik VI, January 21, 2002
• W. Macherey. Speech Recognition for Audio Document Retrieval. "day of computer science", RWTH Aachen, December 7, 2001
• W. Macherey. Tangent Distance in Automatic Speech Recognition. PhD seminar at Lehrstuhl für Informatik VI, RWTH Aachen, October 25, 2001

Teaching

• course work Speech Recognition summer term 2004 (together with Dr. R. Schlüter)
• course work "Datenstrukturen und Algorithmen" summer term 2000 (together with M. Bisani).
  • lecture notes  
• seminar "Data Mining and Learning from Data" winter term 2003/2004
• supervising the topic "Retrieval by Content" (by H. Haegert)
• seminar "Speech Recognition and Language Processing" summer term 2003
• supervising the topic "Discriminative Training" (by L. Haferkamp)
• seminar "Sprach- und Mustererkennung" summer term 2001
• supervising the topic "Content-based Audio Retrieval" (by Y. Moh)
• seminar "Sprach- und Mustererkennung" summer term 2001
• supervising the topic "Finding document boundaries in unstructured text collections" (by G. Leusch)
• seminar "Sprach- und Mustererkennung" summer term 2000
• supervising the topic "Reinforcement Learning" (by N. Bertschinger)
• proseminar "data compression" winter term 2002/2003
• supervising the topic "Querying 1" (by M. Engelberth)
• supervising the topic "Querying 2" (by P. Trinius)
• lab courses
• organization and conduction of the lab course "Speech and Image Processing" for advanced students winter term 2003/2004
• organization and conduction of the lab course "Speech and Image Processing" for advanced students (together with F. Hilger and D. Keysers) winter term 2002/2003
• organization and conduction of the lab course "Speech and Image Processing" for advanced students (together with F. Hilger and D. Keysers) winter term 2001/2002
• diploma theses
  • supervising the diploma thesis "Speaker Clustering for Large Vocabulary Continuous Speech Recognition" (by Y. Moh)
  • supervising the diploma thesis "Vergleich heuristischer und statistischer Verfahren im Information Retrieval" (by J. Viechtbauer)

Projects

• TransType2
• Coretex
• Advisor
• Virtuelle Wissensfabrik