arXiv subjects

Rolf Bader

Publications and source records attributed to Rolf Bader.

17 recordsLinked to original sources

arXiv2025

Non-verbal Perception of Room Acoustics using Multi Dimensional Scaling Metho

Subjective room acoustics impressions play an important role for the performance and reception of music in concert venues and auralizations. Therefore, room acoustics since the 20th century dealt with the relationship between objective, acoustic parameters and subjective impressions of room acoustics. One common approach is to correlate acoustic measures with experts' subjective ratings of rooms as recalled from their long-term memory, and explain them using acoustical measures. Another approach is to let listeners rate auralized room acoustics on bipolar scales and find objective correlates. In this study, we present an alternative approach to characterizing the subjective impressions of room acoustics. We concolve music with binaural room impulse response measurements and utilize Multi Dimensional Scaling (MDS) to identify the perceptual dimensions of room acoustics. Results show that the perception of room acoustics has $5$ dimensions that can be explained by the (psycho-)acoustical measures echo density, fractal correlation dimension, roughness, loudness, and early decay time.

cs.SD↗

arXiv2025

Sound impact of simple viscoelastic damping changes due to aging and the role of the double bentside on soundboard tension in a 1755 Dulcken harpsichord

The sound perception of wood aging is investigated on a Dulcken harpsichord of 1755 from the Museum of Applied Arts in Hamburg, Germany using a Finite-Difference Time Domain (FDTD) model of the harpsichords soundboard. The soundboard thickness was measured on the instrument at 497 positions during strings being deattached and used in the model. Impulse responses were taken on the instrument to estimate the present internal damping by calculating the T60 decay time and used as a model input. By varying the internal damping from this measured damping as a logarithmic decrement, impulse responses were simulated at 52 string positions on both, the 8' and 4' bridge. To estimate the changed sound brightness due to changed internal damping, spectral centroids were calculated from the simulated impulse responses. A dependency of brightness change due to aging on string position was found, where the lower strings have higher brightness, as expected, while the higher strings have decreased brightness. This counterintuitive finding is caused by the frequency-dependent filter effect of changed damping. Future studies need to incorporate viscoelasticity to differentiate this effect further. Furthermore, the attachment of the 8' string to the outer instead of the inner wall, a characteristic feature of Dulcken harpsichords, is investigated using a 3D Finite-Element Method (FEM) model simulation of the whole instrument. No considerable changes on the soundboard tension were found compared to an attachment of the 8' strings to the inner wall, pointing to another reason for this special construction.

cs.SD↗

arXiv2024

Clustering of Indonesian and Western Gamelan Orchestras through Machine Learning of Performance Parameters

Indonesian and Western gamelan ensembles are investigated with respect to performance differences. Thereby, the often exotistic history of this music in the West might be reflected in contemporary tonal system, articulation, or large-scale form differences. Analyzing recordings of four Western and five Indonesian orchestras with respect to tonal systems and timbre features and using self-organizing Kohonen map (SOM) as a machine learning algorithm, a clear clustering between Indonesian and Western ensembles appears using certain psychoacoustic features. These point to a reduced articulation and large-scale form variability of Western ensembles compared to Indonesian ones. The SOM also clusters the ensembles with respect to their tonal systems, but no clusters between Indonesian and Western ensembles can be found in this respect. Therefore, a clear analogy between lower articulatory variability and large-scale form variation and a more exostistic, mediative and calm performance expectation and reception of gamelan in the West therefore appears.

cs.SD↗

arXiv2024

Nonlinear dynamical social and political prediction algorithm for city planning and public participation using the Impulse Pattern Formulation

A nonlinear-dynamical algorithm for city planning is proposed as an Impulse Pattern Formulation (IPF) for predicting relevant parameters like health, artistic freedom, or financial developments of different social or political stakeholders over the cause of a planning process. The IPF has already shown high predictive precision at low computational cost in musical instrument simulations, brain dynamics, and human-human interactions. The social and political IPF consists of three basic equations of system state developments, self-adaptation of stakeholders, two adaptive interactions, and external impact terms suitable for respective planning situations. Typical scenarios of stakeholder interactions and developments are modeled by adjusting a set of system parameters. These include stakeholder reaction to external input, enhanced system stability through self-adaptation, stakeholder convergence due to adaptive interaction, as well as complex dynamics in terms of fixed stakeholder impacts. A workflow for implementing the algorithm in real city planning scenarios is outlined. This workflow includes machine learning of a suitable set of parameters suggesting best-practice planning to aim at the desired development of the planning process and its output.

nlin.AO↗

arXiv2023

Modeling Temporal Lobe Epilepsy during Music Large-Scale Form Perception using the Impulse Pattern Formulation (IPF) Brain Mode

Musical large-scale form is investigated using an Electronic Dance Music (EDM) piece fed into a Finite-Difference Time Domain (FDTD) physical model of the cochlear which again inputs into an Impulse-Pattern Formulation (IPF) brain model. In previous studies, experimental EEG data showed an enhanced correlation between brain synchronization and the musical piece's amplitude and fractal correlation dimension in good agreement with a FitzHugh-Nagumo oscillator model\cite{Sawicki2022}. Still, this model cannot display temporal developments of large-scale forms. The IPF Brain model also shows a high correlation between cochlear input and brain synchronization at the gamma band range around 50 Hz, but also a strong negative correlation for low frequencies, associated with musical rhythm, during time frames of low cochlear input amplitude. Such high synchronization corresponds to temporal lobe epilepsy, often associated with creativity or spirituality. Therefore, the IPF Brain model suggests those conscious states to happen in times of low external input at low frequencies where isochronous musical rhythms are present.

q-bio.NC↗

arXiv2023

Perspectives on adaptive dynamical systems

Adaptivity is a dynamical feature that is omnipresent in nature, socio-economics, and technology. For example, adaptive couplings appear in various real-world systems like the power grid, social, and neural networks, and they form the backbone of closed-loop control strategies and machine learning algorithms. In this article, we provide an interdisciplinary perspective on adaptive systems. We reflect on the notion and terminology of adaptivity in different disciplines and discuss which role adaptivity plays for various fields. We highlight common open challenges, and give perspectives on future research directions, looking to inspire interdisciplinary approaches.

nlin.AO↗

arXiv2023

Impulse Pattern Formulation (IPF) Brain Model

A new brain model is introduced, based on the Impulse Pattern Formulation (IPF) already established for modeling and understanding musical instrument and rhythm perception and production. It assumes the brain works with impulses, neural bursts, ejected from an arbitrary reference point in the brain, arriving at other reflecting brain regions, and returning to the reference point delayed and damped. A plasticity model is suggested to adjust reflection strength in time. The model is systematically studied with 50 reflection points by varying the amount of excitatory vs. inhibitory neurons, the presence or absence of plasticity or external sensory input, and the strength of the input and plasticity in terms of system adaptation to an input or to the system itself. The Brain IPF shows adaptation to an external stimulus, which is stronger without plasticity, showing the active brain not being a simple passive \emph{tabula rasa}. A relation of 10-20\% of inhibitory vs. excitatory neurons, as found in the brain, shows a maximum adaptation to an external stimulus compared to all other relations, pointing to an optimum of this relation concerning adaptation. When assuming strong brain periodicities only up to about 100 Hz, the reflection strength of the model is highest for delays of around 300 ms, corresponding to Event-Related Potential (ERP) timescales of brain potentials most often found roughly between 100 - 400 ms. The mean convergence times of the model correspond to short-time memory time scales with a mean of five seconds for converging IPFs. The Brain IPF is computationally very cheap, highly flexible, and with musical instruments already found to be of high predictive precision. Therefore, in future studies, the Brain IPF might be a model able to understand very large systems composed of an ensemble of brains as well as cultural artifacts and ecological entities.

q-bio.NC↗

arXiv2022

Modelling the perception of music in brain network dynamics

We analyze the influence of music in a network of FitzHugh-Nagumo oscillators with empirical structural connectivity measured in healthy human subjects. We report an increase of coherence between the global dynamics in our network and the input signal induced by a specific music song. We show that the level of coherence depends crucially on the frequency band. We compare our results with experimental data, which also describe global neural synchronization between different brain regions in the gamma-band range and its increase just before transitions between different parts of the musical form (musical high-level events). The results also suggest a separation in musical form-related brain synchronization between high brain frequencies, associated with neocortical activity, and low frequencies in the range of dance movements, associated with interactivity between cortical and subcortical regions.

nlin.AO↗

arXiv2022

Multiphonic modeling using Impulse Pattern Formulation (IPF)

Multiphonics, the presence of multiple pitches within the sound, can be produced in several ways. In wind instruments, they can appear at low blowing pressure when complex fingerings are used. Such multiphonics can be modeled by the Impulse Pattern Formulation (IPF). This top-down method regards musical instruments as systems working with impulses originating from a generating entity, travel through the instrument, are reflected at various positions, and are exponentially damped. Eventually, impulses return to the generating entity and retrigger or interact with subsequent impulses. Due to this straightforward approach, the IPF can explain fundamental principles of complex dynamic systems. While modeling wind instruments played with blowing pressures at the threshold of tone onset, the IPF captures transitions between regular periodicity at nominal pitch, bifurcations, and noise. This corresponds to behavior found in wind instruments where multiphonics appear at the transition between noise and regular musical note regimes. Using the IPF, complex fingerings correspond to multiple reflection points at open finger holes with different reflection strengths. Multiphonics can be modeled if reflection points farther away show higher reflection strength and thus, disrupt periodic motion. The IPF can also synthesize multiphonic sounds by concatenating typical wind instrument waveforms at adjacent impulse time points.

cs.SD↗

arXiv2021

Piano Timbre Development Analysis using Machine Learning

A data set of recorded single played tones of a concert grand piano is investigated using Machine Learning (ML) on psychoacoustic timbre features. The examined instrument has been recorded at two stages: firstly right after manufacture and secondly after being played in a concert hall for one year. A previous study [Plath2019] revealed that listeners clearly distinguished both stages but no clear correlation with acoustics, signal processing tools or verbalizations of perceived differences could be found. Using a Self-Organizing Map (SOM), training single as well as double feature sets, it can be shown that spectral flux is able to perfectly cluster the two stages. Sound Pressure Level (SPL), roughness, and fractal correlation dimension (as a measure for initial transient chaoticity) are furthermore able to order the keys with respect to high and low notes. Combining spectral flux with the three other features in double-feature training sets maintains stage clustering only for SPL and fractal dimension, showing sub-clusters for both stages. These sub-clusters point to a homogenization of SPL for stage 2 with respect to stage 1 and a pronounced ordering and sub-clustering of key regions with respect to initial transient chaoticity.

q-bio.NC↗

arXiv2021

Modeling synchronization in human musical rhythms using Impulse Pattern Formulation (IPF)

When musicians perform in an ensemble, synchronizing to a mutual pace is the foundation of their musical interaction. Clock generators, e.g., metronomes, or drum machines, might assist such synchronization, but these means, in general, will also distort this natural, self-organized, inter-human synchronization process. In this work, the synchronization of musicians to an external rhythm is modeled using the Impulse Pattern Formulation (IPF), an analytical modeling approach for synergetic systems motivated by research on musical instruments. Nonlinear coupling of system components is described as the interaction of individually propagating and exponentially damped impulse trains. The derived model is systematically examined by analyzing its behavior when coupled to numerical designed and carefully controlled rhythmical beat sequences. The results are evaluated by comparison in the light of other publications on tapping. Finally, the IPF model can be applied to analyze the personal rhythmical signature of specific musicians or to replace drum machines and click tracks with more musical and creative solutions.

q-bio.NC↗

arXiv2021

Computational timbre and tonal system similarity analysis of the music of Northern Myanmar-based Kachin compared to Xinjiang-based Uyghur ethnic groups

The music of Northern Myanmar Kachin ethnic group is compared to the music of western China, Xijiang based Uyghur music, using timbre and pitch feature extraction and machine learning. Although separated by Tibet, the muqam tradition of Xinjiang might be found in Kachin music due to myths of Kachin origin, as well as linguistic similarities, e.g., the Kachin term 'makan' for a musical piece. Extractions were performed using the apollon and COMSAR (Computational Music and Sound Archiving) frameworks, on which the Ethnographic Sound Recordings Archive (ESRA) is based, using ethnographic recordings from ESRA next to additional pieces. In terms of pitch, tonal systems were compared using Kohonen self-organizing map (SOM), which clearly clusters Kachin and Uyghur musical pieces. This is mainly caused by the Xinjiang muqam music showing just fifth and fourth, while Kachin pieces tend to have a higher fifth and fourth, next to other dissimilarities. Also, the timbre features of spectral centroid and spectral sharpness standard deviation clearly tells Uyghur from Kachin pieces, where Uyghur music shows much larger deviations. Although more features will be compared in the future, like rhythm or melody, these already strong findings might introduce an alternative comparison methodology of ethnic groups beyond traditional linguistic definitions.

cs.SD↗

arXiv2020

Neural Synchronization of Music Large-Scale Form

Music large-scale form, the structure of musical units ranging over several bars, are studied using EEG measurements of 25 participants listened to the first four minutes of a piece of electronic dance music (EDM). Grand-averages of event-related potentials (ERPs) calculated for all electrodes show dynamics in phase synchronization between different brain regions. Here local maxima of the perceptual parameters correspond to strong synchronization, which culminate at time points, where musical large-scale form boundaries were perceptually expected. Significant differences between local maxima and minima were found, using a Paired Samples t-test, showing global neural synchronization between different brain regions most strongly in the gamma-band EEG frequency range. Such synchronization increases before musical large-scale form boundaries, and decreases afterwards, therefore representing musical large-scale form perception.

q-bio.NC↗

arXiv2020

Neural coincidence detection strategies during perception of multi-pitch musical tones

Multi-pitch perception is investigated in a listening test using 30 recordings of musical sounds with two tones played simultaneously, except for two gong sounds with inharmonic overtone spectrum, judging roughness and separateness as the ability to tell the two tones in each recording apart. 13 sounds were from a Western guitar playing all 13 intervals in one octave, the other sounds were mainly from non-Western instruments comparing familiar with unfamiliar instrument sounds for Western listeners. Additionally the sounds were processed in a cochlear model transferring the mechanical basilar membrane motion into neural spikes followed by a post-processing simulating different degrees of coincidence detection. Separateness perception showed a clear distinction between familiar and unfamiliar sounds, while roughness perception did not. By correlating perception with simulation different perception strategies were found. Familiar sounds correlated strongly positive with high degrees of coincidence detection, where only 3-5 periodicities were left, while unfamiliar sounds correlated with low coincidence levels. This corresponds to an attention to pitch and timbre respectively. Additionally, separateness perception shows an opposite correlation between perception and neural correlates between familiar and unfamiliar sounds. This correlates with the perceptional finding of the distinction between familiar and unfamiliar sounds with separateness.

q-bio.NC↗

arXiv2019

On the Dynamics of the Flow and the Sound Field of an Organ Pipes's Mouth Region

The dynamics of an organ pipe's mouth region has been studied by numerical simulations. The investigations presented here were carried out by solving the compressible Navier-Stokes equations under suitable initial and boundary conditions using parts of the open source C++ toolbox OpenFOAM. The focus of the study is on the examination of the velocity field close to the jet. The components of the velocity field sampled at a cross-section spanning the mouth were analyzed by using methods of coarse-graining. It is shown that the dynamics of the sampled velocity field can be separated into two fractions, a velocity component mainly comprising the jet's flow velocity and a component that essentially carries particle velocity caused by back-propagating sound waves inside the resonator. The SPL-spectra calculated of the data sets of the numerical simulations are compared with the measurements on real organ pipes. The phase-space representations of sound pressure and particle velocity indicate the presence of nonlinearities in the organ pipes's mouth region. The numerical results are consistent with measurements on real organ pipes.

physics.flu-dyn↗

arXiv2018

Cochlear detection of double-slip motion in cello bowing

A double-slip motion of a cello sound is investigated experimentally with a bowing machine and analyzed using a Finite-Difference Time Domain (FDTD) cochlear model. A double-slip sound is investigated. Here the sawtooth motion of normal bowing is basically present, but within each period the bow hair tears off the strings once more within the period, resulting in a blurred sound. This additional intermediate slip appears around the middle of each period and drifts temporally around while the sound progresses. When the double-slip is perfectly in the middle of one period the sound is that of a regular sawtooth motion. If not, two periodicities are present around double the fundamental periodicity, making the sound arbitrary. Analyzing the sound with a Wavelet-transform, the expected double-peak of two periodicities around the second partial cannot be found. Analyzing the tone with a cochlear FDTD model including the transfer of mechanical energy into spikes, the doubling and even more complex behaviour is perfectly represented in the Interspike Interval (ISI) of two adjacent spikes. This cochlear spike representation fits perfectly to an amplitude peak detection algorithm, tracking the precise time point of the double-slip within the fundamental period. Therefore the ear is able to detect the double-slip motion right at the transition from the basilar membrane motion into electrical spikes.

q-bio.NC↗

arXiv2017

Pitch and timbre discrimination at wave-to-spike transition in the cochlea

A new definition of musical pitch is proposed. A Finite-Difference Time Domain (FDTM) model of the cochlea is used to calculate spike trains caused by tone complexes and by a recorded classical guitar tone. All harmonic tone complexes, musical notes, show a narrow-band Interspike Interval (ISI) pattern at the respective fundamental frequency of the tone complex. Still this fundamental frequency is not only present at the bark band holding the respective best frequency of this fundamental frequency, but rather at all bark bands driven by the tone complex partials. This is caused by drop-outs in the basically regular, periodic spike train in the respective bands. These drop-outs are caused by the energy distribution in the wave form, where time spans of low energy are not able to drive spikes. The presence of the fundamental periodicity in all bark bands can be interpreted as pitch. Contrary to pitch, timbre is represented as a wide distribution of different ISIs over bark bands. The definition of pitch is shown to also works with residue pitches. The spike drop-outs in times of low energy of the wave form also cause undertones, integer multiple subdivisions in periodicity, but in no case overtones can appear. This might explain the musical minor scale, which was proposed to be caused by undertones already in 1880 by Hugo Riemann, still until now without knowledge about any physical realization of such undertones.

q-bio.NC↗