193 research outputs found
Psychophysical and physiological evidence for fast binaural processing
The mammalian auditory system is the temporally most precise sensory modality: To localize low-frequency sounds in space, the binaural system can resolve time differences between the ears with microsecond precision. In contrast, the binaural system appears sluggish in tracking changing interaural time differences as they arise from a low-frequency sound source moving along the horizontal plane. For a combined psychophysical and electrophysiological approach, we created a binaural stimulus, called "Phasewarp," that can transmit rapid changes in interaural timing. Using this stimulus, the binaural performance in humans is significantly better than reported previously and comparable with the monaural performance revealed with amplitude-modulated stimuli. Parallel, electrophysiological recordings of binaural brainstem neurons in the gerbil show fast temporal processing of monaural and different types of binaural modulations. In a refined electrophysiological approach that was matched to the psychophysics, the seemingly faster binaural processing of the Phasewarp was confirmed. The current data provide both psychophysical and physiological evidence against a general, hard-wired binaural sluggishness and reconcile previous contradictions of electrophysiological and psychophysical estimates of temporal binaural performance
Institutions of Hanseatic Trade
The merchants of the medieval Hanse monopolised trade in the Baltic and North Sea areas. The authors describe the structure of their trade system in terms of network organisation and attempts to explain, on the grounds of institutional economics, the coordination of the merchantsâ commercial exchange by reputation, trust and culture. The institutional economics approach also allows for a comprehensive analysis of coordination problems arising between merchants, towns and the âKontoreâ. Due to the simplicity and flexibility of network trade the Hansards could bridge the huge gap in economic development between the West and the East. In the changing economic conditions around 1500, however, exactly these characteristics proved to be a serious limit to further retain their trade monopoly
Implementation and Perceptual Evaluation of a Simulation Method for Coupled Rooms in Higher Order Ambisonics
A fast and perceptively plausible method for rendering acoustic scenarios with moving sources and moving listeners is presented. The method is principally suited for application in dynamic and interactive evaluation environments (e.g., for hearing aid development), psycho-physics with adaptively changing the spatial configuration, or simulation and computer games. The simulation distinguishes between the direct sound, sound reflected and diffracted by objects of limited size, diffuse sound surrounding the listener, e.g., diffuse background sounds and diffuse reverberation, and âradiating holesâ for simulation of coupled adjacent rooms. Instead of providing its own simulation of room reverberation, the proposed simulation method generates appropriate output signals for external room reverberation simulators (e.g., see contribution by Wendt et al.). The output of such room reverberation simulators is then taken either as diffuse surrounding sound if the listener position is within the simulated room, or as input into a âradiating holeâ, if the listener is in an adjacent room. Subjective evaluations are performed by comparing measured and synthesized transitions between coupled rooms.DFG, FOR 1732, Individualisierte Hörakustik: Modelle, Algorithmen und Systeme fĂŒr die Sicherstellung der akustischen Wahrnehmung fĂŒr alle in allen Situatione
Evaluation of Virtual Acoustic Environments with Different Acoustic Level of Detail
Virtual acoustic environments enable the creation and simulation of realistic
and ecologically valid daily-life situations with applications in hearing
research and audiology. Hereby, reverberant indoor environments play an
important role. For real-time applications, simplifications in the room
acoustics simulation are required, however, it remains unclear what acoustic
level of detail (ALOD) is necessary to capture all perceptually relevant
effects. This study investigates the effect of varying ALOD in the simulation
of three different real environments, a living room with a coupled kitchen, a
pub, and an underground station. ALOD was varied by generating different
numbers of image sources for early reflections, or by excluding geometrical
room details specific for each environment. The simulations were perceptually
evaluated using headphones in comparison to binaural room impulse responses
measured with a dummy head in the corresponding real environments. The study
assessed the perceived overall difference for a pink pulse, and a speech token.
Furthermore, plausibility and externalization were evaluated. The results show
that a strong reduction in ALOD is possible while obtaining similar
plausibility and externalization as with dummy head recordings. The number and
accuracy of early reflections appear less relevant, provided diffuse late
reverberation is appropriately accounted for.Comment: This work has been submitted to the I3DA 2023 International
Conference on Immersive and 3D Audio for possible publicatio
Perceptual and Room Acoustical Evaluation of a Computational Efficient Binaural Room Impulse Response Simulation Method
A fast and perceptively plausible method for synthesizing binaural room impulse responses (BRIR) is presented. The method is principally suited for application in dynamic and interactive evaluation environments (e. g., for hearing aid development), psychophysics with adaptively changing room reverberation, or simulation and computer games. In order to achieve a low computational cost, the proposed method is based on a hybrid approach. Using the image source model (ISM; Allen and Berkley [J.Acoust. Soc. Am. Vol. 66(4), 1979]), early reflections are computed in a geometrically exact way, taking into account source and listener positions as well as wall absorption and room geometry approximated by a âshoeboxâ. The ISM is restricted to a low order and the reverberant tail is generated by a feedback delay network (FDN; Jot and Chaigne [Proc. 90th AES Conv., 1991]), which offers the advantages of a low computational complexity on the one hand and an explicit control of the frequency dependent decay characteristics on the other hand. The FDN approach was extended, taking spatial room properties into account such as room dimensions and different absorption characteristics of the walls. Moreover, the listener orientation and position in the room is considered to achieve a realistic spatial reverberant field. Technical and subjective evaluations were performed by comparing measured and synthesized BRIRs for various rooms. Mostly, a high accuracy both for some common room acoustical parameters and subjective sound properties was found. In addition, an analysis will be presented of several methods to include room geometry in the FDN.DFG, FOR 1732, Individualisierte Hörakustik: Modelle, Algorithmen und Systeme fĂŒr die Sicherstellung der akustischen Wahrnehmung fĂŒr alle in allen SituationenDFG, EXC 1077/1, Hören fĂŒr alle: Modelle, Technologien und LösungsansĂ€tze fĂŒr Diagnostik, Wiederherstellung und UnterstĂŒtzung des Hören
On the relevance of acoustic measurements for creating realistic virtual acoustic environments
Geometrical approaches for room acoustics simulation have the advantage of
requiring limited computational resources while still achieving a high
perceptual plausibility. A common approach is using the image source model for
direct and early reflections in connection with further simplified models such
as a feedback delay network for the diffuse reverberant tail. When recreating
real spaces as virtual acoustic environments using room acoustics simulation,
the perceptual relevance of individual parameters in the simulation is unclear.
Here we investigate the importance of underlying acoustical measurements and
technical evaluation methods to obtain high-quality room acoustics simulations
in agreement with dummy-head recordings of a real space. We focus on the role
of source directivity. The effect of including measured, modelled, and
omnidirectional source directivity in room acoustics simulations was assessed
in comparison to the measured reference. Technical evaluation strategies to
verify and improve the accuracy of various elements in the simulation
processing chain from source, the room properties, to the receiver are
presented. Perceptual results from an ABX listening experiment with random
speech tokens are shown and compared with technical measures for a ranking of
simulation approaches.Comment: This work has been submitted to the I3DA 2023 International
Conference (IEEE Xplore Digital Library) for possible publication. Copyright
may be transferred without notice, after which this version may no longer be
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