(1) Computational Acoustics deals with the simulation of structure and fluid dynamics, sound field modeling, and associated signal processing tasks. Tasks performed in this field include simulation, mathematical calculation, signal analysis, re-synthesis, and dedicated software development. Research in human and animal auditory perception requires profound knowledge of the physical structures of sound sources and sound fields over a wide range of frequencies. The picture compares the result of a classical Boundary Element Method (BEM) with the Multilevel Fast Multipole Method (MLFMM). The Fast Multipole Method considerably reduces the computational effort without a loss of accuracy.

In the field of (2) Psychoacoustics acoustic measurements, numerical simulations, and Psycho-Physiological Models are applied to specify and explain the function of hearing. The effect of acoustic signals is complex, encompassing daily speech and music listening, environmental noise, motor vehicle acoustics, and audio engineering. One of the main auditory functions concerns masking. The institute's own software package, STx, provides the modeling of simultaneous masking on natural sounds. This masking separates audible spectral components from inaudible ones by computing the so-called "irrelevance threshold."

The Acoustic Model of Speech Production provides the basis of analyzing speech sounds. (3) Acoustic Phonetics, in combination with Phonology, enables the study of articulatory and phonological differences between languages and speakers. Speech parameters, such as fundamental frequency contours, formant frequency tracking, and timing measures support the generation of phoneme and vowel systems as well as relevant linguistic speech sound classifications.

(4) Audiological Acoustics (Hearing with Cochlear Implants): The electrical stimulation of the cochlear nerve by means of Cochlear Implant (CI) systems has been shown to successfully substitute basic functions of the inner ear. In the case of bilateral implantation, left-right localization of sound sources in the horizontal plane can be achieved. The project line aims to transmit additional information to the implant electrodes, thereby enabling the listener to localize sound sources in the horizontal plane as well as in the sagittal planes. Additionally, front-back discrimination should be achieved.

Digital Signal Processing and Mathematics provide a comprehensive framework of tools and knowledge essential for carrying out the research program of the institute. Complex experimental designs generate empirical data and often lead to heuristic models with a modest mathematical basis. Exact mathematical formulations enhance the precision and stability of established algorithms and can be implemented at an early stage of model generation.

The areas of basic and applied research are highly complementary. Many of the different approaches within the two research fields use similar methods. For example, they apply almost the same algorithms of time-frequency representation, digital filters, signal parameter, feature extraction, and common mathematics (Digital Signal Processing and Software Development –S_TOOLS-STx, Mathematics). The framework implemented utilizes the synergistic effects in theoretical and applied fields with the aim to handle the complex interaction between acoustics and auditory perception.