Current

  • Introduction                                                                                                                                                   

    Rumble strips are (typically periodic) grooves place at the side of the road. When a vehicle passes over a rumble strip the noise and vibration in the car should alert the driver of the imminent danger of running off the road. Thus, rumble strips have been shown to have a positive effect on traffic safety. Unfortunately, the use of rumble strips in the close vicinity of populated areas is problematic due to the increased noise burden.

    Aims

    The aim of the project LARS (LärmArme RumpelStreifen or low noise rumble strips) was to find rumble strip designs that cause less noise in the environment without significantly affecting the alerting effect inside the vehicle. For this purpose, a number of conventional designs as well as three alternative concepts were investigated: conical grooves to guide the noise under the car, pseudo-random groove spacing to reduce tonality and thus annoyance, as well as sinusoidal depth profiles which should produce mostly vibration and only little noise and which are already used in practice.

    Methods

    Two test tracks were established covering a range of different milling patterns in order to measure the effects of rumble strips for a car and a commercial vehicle running over them. Acoustic measurements using microphones and a head-and-torso-simulator were done inside the vehicle as well as in the surroundings of the track. Furthermore, the vibration of the steering wheel and the driver seat were measured. Using the acoustics measurements, synthetic rumble strip noises were produced, in order to get a wider range of possible rumble strip designs than by pure measurements.

    Perception tests with 16 listeners were performed where the annoyance of the immissions as well as the urgency and reaction times for the sounds generated in the interior were determined also using the synthetic stimuli.

    LARS was funded by the FFG (project 840515) and the ASFINAG. The project was done in cooperation with the Research Center of Railway Engineering, Traffic Economics and Ropeways, Institute of Transportation, Vienna University of Technology, and ABF Strassensanierungs GmbH.

  • Objective:

    The aim of this study is to investigate the phonetics of second language acquisition and first language attrition, based on the acoustic and articulatory lateral realizations of Bosnian migrants living in Vienna. Bosnian has two lateral phonemes (a palatalized and an alveolar/velarized one), whereas Standard Austrian German features only one lateral phoneme (an alveolar lateral). In the Viennese dialect however, this phoneme also has a velarized variant.

    This phonetic investigation will be conducted with respect to the influence of language contact between Bosnian and SAG, and Bosnian and the Viennese dialect, as well as concerning the influence of gender and identity construction.

    Method:

    The recordings will be conducted with female and male Bosnian speakers, aged between 20 and 35 years at the time of emigration, who came to Vienna during the Bosnian war 1992-1995. Additionally, control groups of monolingual L1 speakers of Bosnian, SAG and Vd will be recorded. All recordings will include reading tasks in order to elicit controlled speech, as well as spontaneous speech in the form of biographical interviews. The analyses will comprise quantitative and qualitative aspects. Quantitatively, the acoustic parameters formant frequencies (especially F2 and F3), duration and intensity of the laterals and their phonetic surrounding will be analyzed. Additionally, articulatory analyses will be performed using EPG and UTI data. Qualitatively, biographical information, language attitudes and social networks will be analysed in order to obtain information about speaker-specific or group-specific characteristics.

    Application:

    The results of this study are relevant to understanding the processes of sound-realization and sound-change in the domains of language contact (phonetic processes in second language acquisition and first language attrition), sociolinguistics, and the sociology of identity construction

  • Objective:

    Head-related transfer functions (HRTFs) describe sound transmission from the free field to a place in the ear canal in terms of linear time-invariant systems. They contain spectral and temporal features that vary according to the sound direction. Differences among subjects requires the measuring of subjects' individual HRTFs for studies on localization in virtual environments. In this project, a system for HRTF measurement was developed and installed in the semi-anechoic room at the Austrian Academy of Sciences.

    Method:

    Measurement of an HRTF was considered a system identification of the electro-acoustic chain: sound source-room-HRTF-microphone. The sounds in the ear canals were captured using in-ear microphones. The direction of the sound source was varied horizontally by rotating the subject on a turntable, and vertically by accessing one of the 22 loudspeakers positioned in the median plane. An optimized form of system identification with sweeps, the multiple exponential sweep method (MESM), was used for the measurement of transfer functions with satisfactory signal-to-noise ratios occurring within a reasonable amount of time. Subjects' positions were tracked during the measurement to ensure sufficient measurement accuracy. Measurement of headphone transfer functions was included in the HRTF measurement procedure. This allows equalization of headphone influence during the presentation of virtual stimuli.

    Results:

    Multi-channel audio equipment has been installed in the semi-anechoic room, giving access to recording and stimuli presentation via 24 channels simultaneously.

    The multiple exponential sweep method was developed, allowing fast transfer function measurement of weakly non-linear time invariant systems for multiple sources.

    The measurement procedure was developed and a database of HRTFs was created. Until now, HRTF data for over 20 subjects had not been available to create virtual stimuli and present them via headphones.

    To virtually position sounds in space, the HRTFs are used for filtering free-field sounds. This results in virtual acoustic stimuli (VAS). To create VAS and present them via headphones, applications called Virtual Sound Positioning (VSP) and Loca (Part of our ExpSuite Software Project) have been implemented. It allows virtual sound positioning in a free-field environment using both stationary and moving sound sources

  • Objective:

    The modeling step in speaker detection has an enormous influence on the classification task, because the quality of the model depends on the parameters chosen in this step. False classifications, false identifications, and false verifications can result from malformed speaker models. The initial model parameters have an influence on the final determined parameters of the speaker models. To obtain optimized speaker models, different initialization methods are explored.

    Method:

    Speaker models are represented as Gaussian Mixture Models (GMMs). These models are mixtures of multivariate distributions that are parameterized by the means and the co-variance matrices of the distributions and the mixture weights. The parameters are estimated by the expectation maximization algorithm (EM algorithm) which maximizes the likelihood in the model. Initial model parameters have to be selected for this algorithm. Different initial parameters can lead to a convergence of the algorithm in local maximums. The effect of different initialization methods on the identification rate is analyzed.

    Application:

    Optimized speaker models reflect the speech behavior of the speakers in an optimal way. The inter-speaker variability is maximized while the intra-speaker variability is minimized by avoidance of malformed speaker models. The usage of optimal initialization methods improves the robustness and the reliability of automatic speaker identification and verification systems.

  • Objective:

    Methods to predict the propagation of vibrations in soil are relatively undeveloped. Reasons for this include the complexity of the wave propagation in soil and the insufficient knowledge of material parameters. During this project a method was developed to simulate the propagation of vibrations that are caused by a load at the base of a tunnel.

    Method:

    When dealing with the model of a tunnel in a semi-infinite domain like soil, the boundary element method (BEM) seems to be an appropriate tool. Unfortunately it cannot be applied directly to layered orthotropic media, because of the lack of a closed form of the Greens function, which is essential for BEM. But by transforming the whole system into the Fourier domain with respect to space and time, it is possible to numerically construct an approximation for this function on a predefined grid. With this approximation the boundary integral equation, that describes the propagation of waves caused by a vibrating load at the base of a tunnel can be solved.

    Application:

    Models that can help to predict the propagation of vibrations inside soil layers are of great interest in earthquake sciences or when constructing railway lines and tunnels.

  • Introduction

    Railway vehicles passing through tight curves can produce a high pitched noise called curve squeal. Curve squeal is a very salient type of noise located in the high frequency range that can range between a tonal narrow band and a wide band noise. The reason for the tonal noise is lateral creepage on the top of the rail, which excites wheel vibration at frequencies corresponding to their modes. Wide band noise, however, is caused by wheel flanges touching the rail.

    Aims

    The project PAAB aims at investigating the effect on the perceived annoyance of such noises using in a perception test. Using the resulting perceptual characterization of curve squeal should aid in more adequately considering this type of noise in noise mapping.

    Methods

    Based on previous conventional large-scale emission measurements as well as new measurements at immission distances using a head-and-torso-simulator representative samples for curve squeal will be derived and used in a perception test. This will also be aided by using synthetic well defined curve squeal noise.

    PAAB is funded by the FFG (project 860523) and the Austrian Federal Railways (ÖBB). The project is done in cooperation with the Research Center of Railway Engineering, Traffic Economics and Ropeways, Institute of Transportation, Vienna University of Technololgy (project leader), Kirisits Engineering Consultants, and psiacoustic Umweltforschung und Engineering GmbH.

     

     

  • Objective:

    Numerous implementations and algorithms for time frequency analysis can be found in literature or on the internet. Most of them are either not well documented or no longer maintained. P. Soendergaard started to develop the Linear Time Frequency Toolbox for MATLAB. It is the goal of this project to find typical applications of this toolbox in acoustic applications, as well as incorporate successful, not-yet-implemented algorithms in STx.

    Method:

    The linear time-frequency toolbox is a small open-source Matlab toolbox with functions for working with Gabor frames for finite sequences. It includes 1D Discrete Gabor Transform (sampled STFT) with inverse. It works with full-length windows and short windows. It computes the canonical dual and canonical tight windows.

    Application:

    These algorithms are used for acoustic applications, like formants, data compression, or de-noising. These implementations are compared to the ones in STx, and will be implemented in this software package if they improve its performance.

    Partners:

    • H. G. Feichtinger et al., NuHAG, Faculty of Mathematics, University of Vienna
    • B. Torrèsani, Groupe de Traitement du Signal, Laboratoire d'Analyse Topologie et Probabilités, LATP/ CMI, Université de Provence, Marseille
    • P. Soendergaard, Department of Mathematics, Technical University of Denmark
  • The spatially oriented format for acoustics (SOFA) is dedicated to store all kinds of acoustic informations related to a specified geometrical setup. The main task is to describe simple HRTF measurements, but SOFA also aims to provide the functionality to store measurements of something fancy like BRIRs with a 64-channel mic-array in a multi-source excitation situation or directivity measurement of a loudspeaker. The format is intended to be easily extendable, highly portable, and actually the greatest common divider of all publicly available HRTF databases at the moment of writing.

    SOFA defines the structure of data and meta data and stores them in a numerical container. The data description will be a hierarchical description when coming from free-field HRTFs (simple setup) and going to more complex setups like mic-array measurements in reverberant spaces, excited by a loudspeaker array (complex setup). We will use global geometry description (related to the room), and local geometry description (related to the listener/source) without limiting the number of acoustic transmitters and receivers. Room descriptions will be available by linking a CAD file within SOFA. Networking support will be provided as well allowing to remotely access HRTFs and BRIRs from client computers.

    SOFA is being developed by many contributors worldwide. The development is coordinated at ARI by Piotr Majdak.

    Further information:

    www.sofaconventions.org.
  • Baumgartner et al. (2017a)

    Spatial hearing is important to monitor the environment for interesting or hazardous sounds and to selectively attend to them. The spatial separation between the two ears and the complex geometry of the human body provide auditory cues about the location of a sound source. Depending on where a sound is coming from, the pinna (or auricle) changes the sound spectrum before the sound reaches the eardrum. Since the shape of a pinna is highly individual (even more so than a finger print) it also affects the spectral cues in a very individual manner. In order to produce realistic auditory perception artificially, this individuality needs to be reflected as precisely as required, whereby the actual requirements are currently unclear. That is why SpExCue was about finding electrophysiological measures and prediction models of how spatially realistic (“externalized”) a virtual sound source is perceived to be.

    Virtual and augmented reality (VR/AR) systems aim to immerse a listener into a well-externalized 3D auditory space. This requires a perceptually accurate simulation of the listener’s natural acoustic exposure. Particularly challenging is to appropriately represent the high-frequency spectral cues induced by the pinnae. To simplify this task, we aim at developing a phenomenological computational model for sound externalization with a particular focus on spectral cues. The model will be designed to predict the listener’s degree of externalization based on binaural input signals and the listener’s individual head-related transfer functions (HRTFs) under static listening conditions.

    The naturally externalized auditory perception can be disrupted, for instance, when listening via headphones or hearing-assistive devices, and instead sounds are heard inside the head. Because of this change in externalization or perceived distance, our investigations of spectral cues also served to study the phenomenon of auditory looming bias (Baumgartner et al., 2017a): sounds approaching the listener are perceived more intensely than those that are receding from the listener. Previous studies demonstrated auditory looming bias exclusively by loudness changes (increasing/decreasing loudness used to simulate approaching/receding sounds). Hence, it was not clear whether this bias truly reflects perceptual differences in sensitivity to motion direction rather than changes in loudness. Our spectral cue changes were perceived as either approaching or receding at steady loudness and evoked auditory looming bias both on a behavioral level (approaching sounds easier to recognize than receding sounds) and an electrophysiological level (larger neural activity in response to approaching sounds). Therefore, our study demonstrated that the bias is truly about perceived motion in distance, not loudness changes.

    Further, SpExCue investigated how the combination of different auditory spatial cues affects attentional control in a speech recognition task with simultaneous talkers, which requires spatial selective attention like in a cocktail party (Deng et al., in prep). We found that natural combinations of auditory spatial cues caused larger neural activity in preparation to the test signal and optimized the neural processing of the attended speech.

    SpExCue also compared different computational modeling approaches that aim to predict the effect of spectral cue changes on how spatially realistic a sound is perceived (Baumgartner et al., 2017b). Although many previous experimental results could be predicted by at least one of the models, none of them alone could explain these results. In order to assist the future design of more general computational models for spatial hearing, we finally created a conceptual cognitive model for the formation of auditory space (Majdak et al., in prep.).

    Funding

    Erwin-Schrödinger Fellowship from Austrian Science Funds (FWF, J3803-N30) awarded to Robert Baumgartner. Duration: May 2016 - November 2017.

    Follow-up funding provided by Oculus VR, LLC, since March 2018. Project Investigator: Robert Baumgartner.

    Publications

    • Baumgartner, R., Reed, D.K., Tóth, B., Best, V., Majdak, P., Colburn H.S., Shinn-Cunningham B. (2017a): Asymmetries in behavioral and neural responses to spectral cues demonstrate the generality of auditory looming bias, in: Proceedings of the National Academy of Sciences of the USA 114, 9743-9748. (article)
    • Baumgartner, R., Majdak, P., Colburn H.S., Shinn-Cunningham B. (2017b): Modeling Sound Externalization Based on Listener-specific Spectral Cues, presented at: Acoustics ‘17 Boston: The 3rd Joint Meeting of the Acoustical Society of America and the European Acoustics Association. Boston, MA, USA. (conference)
    • Deng, Yuqi, Choi, Inyong, Shinn-Cunningham, Barbara G., Baumgartner, Robert (2019): Impoverished auditory cues fail to engage brain networks controlling spatial selective attention, in: bioRxiv, 533117. (preprint)
    • Majdak, Piotr, Baumgartner, Robert, Jenny, Claudia (2019): Formation of three-dimensional auditory space, in: arXiv:1901.03990 [q-bio]. (preprint)
  • Objective:

    In the past a FWF project dealing with the basics of Stochastic Transformation Methods was executed at the ARI. Explicitly the Karhunen Loeve Expansion and the Transformation of a polynomial Chaos were applied in the wave number domain. The procedure is based on the assumption of Gaussian distributed variables. This assumption shall be generalized to arbitrary random variables.

    Method:

    The assumption of a wave number domain limits the model to a horizontally layered half space. This limitation shall be overcome by Wavelets kernels in the transformation instead of Fourier kernels. The aim is the possibility to calculated one sided statistical distributions for the physical parameters and arbitrary boundaries with the new method.

  • Multilateral Scientific and Technological Cooperation in the Danube Region 2017-2018
    Austria, Czech Republic, Republic of Serbia, and Slovak Republic
    Project duration: 01.01.2017 - 31.12.2018

    Project website: nuhag.eu/tifmofus

  • Project Part 02 of the special research area German in Austria. Variation - Contact - Perception funded by FWF (FWF6002) in cooperation with the University of Salzburg

    Principal Investigators: Stephan Elspaß, Hannes Scheutz, Sylvia Moosmüller

    Start of the project: 1st of January 2016

    Project description:

    The diversity and dynamics of the various dialects in Austria are the topic of this project. Based on a new survey, different research questions will be addressed in the coming years, such as: What are the differences and changes (e.g. through processes of convergence and divergence) that can be observed within and between the Austrian dialect regions? What are the alterations in dialect change between urban and rural areas? Are there noticeable generational and gender differences with regard to dialect change? What can a comprehensive comparison of ‘real-time’ and ‘apparent-time’ analyses contribute to a general theory of language change?

    To answer these questions, speech samples from a total of 160 dialect speakers, balanced for age and gender, are collected and analysed within the first four years at 40 locations in Austria. Furthermore, samples from selected speakers will be recorded and valuated under laboratory conditions to determine phonetic peculiarities as precisely as possible. In the second survey phase complementary recordings are carried out at another 100 locations in Austria in order to analyse differences and changes between the dialect landscapes in more detail. State-of-the-art dialectometric methods will be used to arrive at probabilistic statements regarding dialect variation and change in Austria. The analyses will include all linguistic levels from phonetics to syntax and lexis. A documentation of these data will be carried out on the first visual and ‘talking’ dialect atlas of Austria.

    Project page of the project partners in Salzburg

     

  • Objective:

    One of the biggest problems encountered when building numerical models for layers is the lack of exact deterministic material parameters. Therefore, stochastic models should be use. However, these models have the general drawback of overusing computer resources. This project developed a stochastic model with the ability to use a shear modulus in conjunction with a special iteration scheme allowing efficient implementation.

    Method:

    With the Karhunen Loeve Expansion (KLE), it is possible to split the stochastic shear modulus, and therefore the whole system, into a deterministic and a stochastic part. These parts can then be transformed into a linear system of equations using finite elements and Chaos Polynomial Decomposition. Combining the KLE and the Fourier Transformation in combination with Plancherel's theorem enables decoupling of the deterministic part into smaller subsystems. An iteration scheme was developed which narrows the application of "costly" routines to only these smaller deterministic subsystems, instead of the whole higher dimensional (up to a dimension of 10,000) system matrix.

    Application:

    As concerns about vibrations produced by machinery and traffic have increased in past years, models that can predict vibrations in soil became more important. However, since material parameters for soil layers cannot be measured exactly in practice, it is reasonable to use stochastic models.

  • Vowel and consonant quantity in Southern German varieties: D - A - CH project granted by DFG, FWF, SNF

    Principal investigators: Felicias Kleber, Michael Pucher, Sylvia Moosmüller†, Stephan Schmid 

    Start of the project: 1st of June 2015

    Project description:

    Introduction:

    The Central Bavarian varieties, to which the Viennese varieties belong, seem to have changed diachronically. From the first phonetic descriptions (Pfalz 1913) to more current descriptions (Moosmüller & Brandstätter 2014) the diachronic change becomes visible on several levels of the varieties.

    In this project we focus on the (in)stability of the timing system, or more precise, the quantity relations in Vowel + Consonant sequences and compare our results with the project partners in Zurich and Munich.

    Aims:

    The aims of this project are two-fold. The first aim is to develop a typology of the Vowel + Consonant quantities in Southern German varieties (Bavarian (Munich + Vienna) and Alemannic (Zurich)) in C1V1C2V2contexts (where C2can be either fricatives or nasals or plosives) and in consonant cluster sequences with increasing initial and final consonant cluster complexity. The second aim is to investigate prosodic changes in an apparent-time study and to examine the influence of internal factors (eg. speech rate) and external factors (language attitudes) on the production of speech.

    Method:

    Recordings and analyses of 40 speakers of the Viennese varieties (balanced for age, gender, and educational background) will be conducted. During the recording sessions the speakers are asked to read and repeat sentences in two speech rates. Furthermore a subset of speakers is asked to participate in an articulatory recording with an electromagnetic articulograph (EMA). These recordings take place at our project partners’ laboratory in Munich.

    Application:

    The results will not only provide insight in the current timing system of speakers of the Viennese varieties but also enable us to draw conclusions about sound changes in progress.

     

  • Introduction

    Railway platforms are located very close to the track and thus are assumed to alter the sound propagation. The degree of this effect, however, has not yet been investigated in detail

    Aims

    The aim of the project WiaBahn was to investigate the shielding effect of railway platforms. One of the main questions was how to properly deal with the vicinity to the track, the platform’s large reflecting horizontal surface, and the often present canopy. It is unclear whether standard noise propagation prediction methods can be applied without modifications.

    Methods

    Based on measurements directly at the platform as well as in the distance the acoustic effect of low railway platforms was investigated and suitable source models for the 2.5D boundary element method (BEM) as well as for standardized prediction methods were derived. The advantage of the 2.5D method which was also used in the project PASS is, that a constant cross-section can be combined with point sources or incoherent line sources which is not possible with pure 2D methods. 3D BEM is not feasible for such large structures.

    WiaBahn was funded by the FFG (project 845678) and the ÖBB. The project was done in cooperation with the  Austrian Institute of Technology (AIT, project leader) and Kirisits Engineering Consultants.