Manuj Yadav: Open-plan office acoustics and some other research projects within Acoustics Lab, The University of Sydney
Jul 5 um 11:00 – 12:00

This talk will present highlights from some recent research projects, both active and dormant, within the Acoustics Lab in the School of Architecture, Design and Planning, The University of Sydney. Focus will mostly be on recent findings from studies investigating several aspects of open-plan office acoustics. These studies have included field research in Australian offices using the international room acoustics standard for open-plan offices (ISO 3382-3:2012), occupant surveys and binaural recordings of office sound environments during working hours, and more controlled laboratory studies conducted in a medium-sized open-plan office simulation within a climate chamber. The other topics briefly presented will include studies of autophonic (one’s own voice) perception with talkers and singers using virtual acoustics, characterizing the local acoustic effects of high-back chairs, stage acoustics for chamber musicians, acoustic retroreflection, etc. The overall aim is to provide a glimpse into several projects that range from those generating practical findings that are more readily implemented, to those that are somewhat arcane (and thus, fun) while still basic enough to warrant further research.

Anne Heimes: Filter Design for Sound Insulation Auralization
Aug 9 um 11:00 – 11:30

As a valuable tool, building acoustic auralization is used to assess the perceptual aspects of sound transmission in built-up environments in order to provide the guidelines for building construction and to evaluate the noise effects on humans that have a negative influence on their working performances at working sites. These noise disturbances are present within the built environments and/or might be from outdoor moving transient sound sources. An extensive research is carried out to estimate the sound propagation and transmission in the buildings. Methods are available for auralization of sound insulation between connected rooms in compliance with the standardized data formats of sound insulation and building structural geometries. However, there still exist certain challenges to be addressed to construct the transfer functions between source and receiver rooms for indoor situation as well as for outdoor moving sources.

Several simplifications exist in available building acoustic auralization research. Some simplifications are implicit in the formulation on which the ISO standards are based. In first place, the incident sound pressure on the boundaries of the building elements (i.e. walls) is equal for all transmission paths between source and the receiver. Similarly, the same incident sound power hits all elements, independently of the source position and room geometry. Additionally, influence of the source room reverberation, the directionality of the sound source, and the ratio between direct and reverberant energy inside the source room are integral part of building acoustic transfer functions, which are rarely addressed. Secondly, the transfer functions calculated from source room to receiver room are only valid for point to point transmission, however, the extended walls are always present in real situations. In the receiving room, the simplification is made that the sound is apparently radiated from one point representing the whole bending wave pattern on the wall, as a result one whole wall is represented by a single point source radiator.

This research focuses on addressing these challenges for plausible representation of building acoustics auralization. The building elements are considered as plane sources and bending wave patterns are addressed in order to be able to properly construct the transfer functions. The room acoustical simulations are carried out for both source and receiving rooms to generate transfer functions from source to the source room walls and from radiating receiving room walls to the listener, so that the geometries and absorptions might be fit to the properties desired by the user for the spatial impression of the listening rooms. In addition, the transfer functions from radiating walls of the receiving room to listener are designed in such a way that not only indoor sources are handled nevertheless the outdoor moving sources are also addressed. In this way a physically more plausible building acoustic auralization framework is proposed, by dint of that different psychoacoustic experiments are possible in virtual reality for evaluation of noise and comfort in built-up structures and psychological research about the work performance of people at office sites under undesirable noise conditions can be carried out in an ecologically correct way.

Teresa Pelinski Ramos: Simplified binaural receivers for low frequency range acoustical simulations
Aug 16 um 11:00 – 11:30

This thesis addresses the geometrical modelling for binaural receivers in numerical acoustic simulations in the low frequency range. Within this range, the wavelength is usually large in comparison to the fine structure of head and torso. Consequently, geometric details, such as the pinna or the nose, have no significant influence on the head-related transfer functions (HRTFs). This suggests that for low frequencies, binaural receivers can be modelled using a simplified geometry to reduce the number of mesh nodes (and therefore the computational complexity) without compromising the accuracy of the simulation results.

In the course of this thesis, different simplified geometrical models for binaural receivers for low frequency range simulations will be discussed. In order to evaluate the performance of these models, the corresponding HRTFs will be simulated using the boundary element method (BEM) and compared to measured HRTFs. As an indicator of the computational complexity, the number of required mesh nodes will be evaluated for different frequencies.

Julia Wagener: Untersuchungen zum binauralen Sprachübertragungsindex in Klassenräumen
Aug 23 um 11:00 – 11:30

Wann das menschliche Gehör Schall als Lärm empfindet, ist sehr subjektiv. Schon von klein auf wird der Mensch jeden Tag durch laute Geräusche belastet. Die konventionellen und standardisierten (monauralen) Messmethoden können jedoch nicht deutlich zeigen, wie komplex Schall beziehungsweise Lärm vom Menschen wahrgenommen wird. Dafür wurden in der Psycho- und Raumakustik erste binaurale Modelle entwickelt, welche auf der Körpergeometrie und kognitiven Wahrnehmung von Erwachsenen basieren. Dabei ist noch unbekannt, ob diese Modelle auch für Kinder anwendbar sind, da sich die Physiologie und Wahrnehmung von der eines Erwachsenen unterscheidet. Auf diesem Gebiet wurden bereits erste Forschungen angestellt, die noch keine signifikanten Ergebnisse lieferten. In dieser Bachelorarbeit werden die Auswirkungen von verschiedenen Erfassungsmethoden auf den binauralen Sprachübertragungsindex mit Erwachsenen- und Kinderkunstköpfen untersucht.

Dafür werden ein indirektes und ein direktes Messverfahren nach DIN 60268-16-2012-05 zur Messung des Speech Transmission Indexes (STI) verwendet. Das indirekte Verfahren beruht auf einer mathematischen Modifikation der Impulsantwort durch die Schroeder-Gleichung, mit der die Modulationsübertragungsfunktion (MTF) berechnet wird. Beim direkten Messverfahren andererseits, wird mithilfe eines auf geeignete Art und Weise modulierten Prüfsignals der STI gemessen.

Die Einflüsse der beiden unterschiedlichen Empfänger in beiden Messmethoden werden in dieser Arbeit miteinander verglichen und die Vor- und Nachteile werden in Betrachtung des Arbeitsaufwandes und vor allem basierend auf Ergebnissen von binauralen Modellen aufgezeigt.