Báo cáo hóa học: Editorial Werner Verhelst Department of Electronics and Information Processing,

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Báo cáo hóa học: " Editorial Werner Verhelst Department of Electronics and Information Processing, "EURASIP Journal on Applied Signal Processing 2005:9, 1289–1291 c 2005 Hindawi Publishing CorporationEditorial Werner Verhelst Department of Electronics and Information Processing, Vrije Universiteit Brussel, 1050 Brussel, Belgium Email: wverhels@etro.vub.ac.be ¨ Jurgen Herre Fraunhofer Institute for Integrated Circuits (IIS), 91058 Erlangen, Germany Email: hrr@iis.fhg.de Gernot Kubin Signal Processing and Speech Communication Laboratory, Graz University of Technology, 8010 Graz, Austria Email: g.kubin@ieee.org Hynek Hermansky IDIAP Research Institute, 1920 Martigny, Switzerland Email: hynek@idiap.ch Søren Holdt Jensen Department of Communication Technology, Institute of Electronic Systems, Aalborg University, Fredrik Bajers Vej 7A, DK-9220 Aalborg, Denmark Email: shj@kom.aau.dkAnthropomorphic systems process signals “at the image of technology that is chosen for the implementation (airplanesman.” They are designed to solve a problem in signal process- do not flap their wings because it is technically much more efficient to use jet engines for propulsion). Nevertheless, a loting by imitation of the processes that accomplish the sametask in humans. In the area of audio and speech processing, can be learned from imitating natural systems that were opti-remarkable successes have been obtained by anthropomor- mized through natural selection. As such, anthropomorphicphic systems: perceptual audio coding even caused a land- and, by extension, biomorphic systems can be considered toslide in the music business. play an important role in the process of developing new tech- At first sight, it could seem obvious that the performance nologies.of audio processing systems should benefit from taking into This special issue brings together a dozen papers from different areas of audio and speech processing that deal withaccount the perceptual properties of human audition. For ex-ample, front ends that extract perceptually meaningful fea- aspects of anthropomorphic processing or in which an an-tures currently show the best results in speech recognizers. thropomorphic or perceptual approach was taken.However, their features are typically used for a stochastic op- The first of two papers on perceptual audio coding pro-timization that is itself not anthropomorphic at all. Thus, it is poses a perceptual model for the specific distortion that isnot obvious why they should perform best, and perhaps the typically encountered in sinusoidal modelling, while the sec-truly optimal features have not yet been found because, after ond paper introduces a novel parametric stereo coding tech-all, “airplanes do not flap their wings.” nique based on binaural psychoacoustics. While these papers illustrate the use of human auditory perception for efficient In general, we believe that there are several situationswhen an anthropomorphic approach may not be the best so- audio coding, the three following papers present examples of efforts towards using different levels of neurophysiologiclution. First, its combination with nonanthropomorphic sys-tems could result in a suboptimal overall performance (the modelling directly for the representation and processing ofquantization noise that was cleverly concealed by a percep- audio signals: from a model for the adaptation behaviourtual audio coder could become unmasked by subsequent lin- in the chemical synapses between the inner hair cells andear or nonlinear processing). Second, other approaches that the auditory neurons, to a signal processing model for theare not anthropomorphic might be better adapted to the early auditory system, and then a cortical audio representa-1290 EURASIP Journal on Applied Signal Processingtion for sound modification. In the last pair of audio papers, Since the end of 1996, he has returned to Fraunhofer to work on the development of advanced multimedia technologies ...