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Promotionsvortrag: Adaptive Algorithms for the Identification of Time-Variant Acoustic Systems

Stefan Kühl
Montag, 7.März 2022
11:00 Uhr
virtueller Konferenzraum

Many digital speech and audio communication systems incorporate models of acoustic systems during signal processing. Often, the impulse responses of these acoustic systems have to be identified during or before using a communication system by means of adaptive algorithms.

Acoustic systems describe how sound is affected during transmission between a source and a receiver. Examples of acoustic systems comprise rooms with reflections from boundaries and scattering from objects, communication devices such as smartphones or smart home devices, or even a human head where shadowing effects occur. In many situations, the impulse responses of these systems need to be identified. Possible scenarios are acoustic measurements or system identification in speech communication applications, e.g., for accoustic echo cancellation (AEC). Depending on the specific use case, vertain aspects have to be taken into account. For a measurement the excitation signal can be designed, whereas for speech communication applications the system's excitation is the speech signal that cannot be altered. Hence, for the latter case, correlation has to be considered during the system identification. In addition, the systems to be identified may vary over time when the acoustic environment changes, e.g., due to moving objects. Therefore, adaptive algorithms must be used to track the system's state. Additional challenges arise when considering the identification of multiple channels simultaneously.

This thesis considers different aspects of systems identification of time-variant acoustic systems in a joint framework for diverse scenarios.