Robert Höldrich

University of Music and Performing Arts Graz | KUG · IEM - Institute of Electronic Music and Acoustics

The research communities studying visualization and sonification for data display and analysis share exceptionally similar goals, essentially making data of any kind interpretable to humans. One community does so by using visual representations of data, and the other community employs auditory (non‐speech) representations of data. While the two com...

In 1997, Flowers, Buhman, and Turnage published a paper titled ``Cross-Modal Equivalence of Visual and Auditory Scatterplots for Exploring Bivariate Data Samples.'' This paper examined our capacity to assess the relationship between two data variables when presented through visual or auditory scatterplots. Twenty-seven years later, we have replicat...

Guest editors' note on the Special Issue on Sonification in the AES: Journal of the Audio Engineering Society

One of the commonly used visualization techniques for multivariate data is the parallel coordinates plot. It provides users with a visual overview of multivariate data and the possibility to interactively explore it. While pattern recognition is a strength of the human visual system, it is also a strength of the auditory system. Inspired by the int...

Both sonification and visualization convey information about data by effectively using our human perceptual system, but their ways to transform the data differ. Over the past 30 years, the sonification community has demanded a holistic perspective on data representation, including audio-visual analysis, several times. A design theory of audio-visua...

When encountering a physical object that occludes its inner structure or content, we often resort to a tried and tested remedy: hit and listen. The resulting auditory feedback conveys information on the physical properties of the involved objects (e.g., material and geometry) and the performed action. For the interpretation of such auditory feedbac...

For unknown physical objects, we often infer the “ground truth” (e.g., on material, hollowness, or thickness) that is hidden below the visual appearance by percussion, i.e., by knocking on them. Auditory augmentations embed digital information into physical objects by modulating their auditory feedback in a plausible way. Based on physically justif...

For every physical interaction with our environment, we have some expectations concerning the resulting sound. As these expectations are quite rough, the auditory feedback can be modulated to convey additional information, without restricting the object's original purpose. Such auditory augmentation is calm and unobtrusive as long it stays plausibl...

Auditory feedback from everyday interactions can be augmented to project digital information in the physical world. For that purpose, auditory augmentation modulates irrelevant aspects of already existing sounds while at the same time preserving relevant ones. A strategy for maintaining a certain level of plausibility is to metaphorically modulate...

While traditional reed blocks of Styrian harmonicas are made of wood, 3D-printing offers new possibilities, but requires different materials. Our contribution investigates the influence of the material on the radiated sound of a reed block and its surface vibration. Therefore seven geometrically identical reed blocks made of different materials wer...

Both sonification and visualization convey information about data by effectively using our human perceptual system, but their ways to transform the data could not be more different. The sonification community has demanded a holistic perspective on data representation, including audio-visual analysis, several times during the past 30 years. A design...

Im Alltag ist es oft möglich, physikalische Objekte anhand des Klangs, der durch Tasten, Klopfen oder Kratzen hervorgerufen wird, zu unterscheiden. Die Wahrnehmbarkeit von Objekteigenschaften wie Material, Form, Größe durch dieses akustische Feedback wurde bereits eingehend untersucht. Ziel im durchführten Projekt war es deshalb, ein Verfahren zu e...

Peripheral interaction is a new approach to conveying information at the periphery of human attention in which sound is so far largely underrepresented. We report on two experiments that explore the concept of sonifying information by adding virtual reverberation to real-world room acoustics. First, to establish proof of concept, we used the consum...

Studies on the precedence effect are typically conducted by presenting two identical sounds simulating direct sound and specular reflection. However, when a sound is reflected from irregular surface, it is redirect into many directions resulting in directional and temporal diffusion. This contribution introduces a simulation of Lambertian diffusing...

We present a sonification method which we call Focused Audification (FA; previously: Augmented Audification) that allows to expand pure audification in a flexible way. It is based on a combination of single-side-band modulation and a pitch modulation of the original data stream. Based on two free parameters, the sonification’s frequency range is ad...

CardioScope is a sonification/auditory augmentation tool intended to support cardiac diagnosis and monitoring. It allows users to record and visualize synchronized Electrocardiogram (ECG) and Phonocardiogram (PCG) signals, to sonify the electrical activity of the heart or to augment the sound produced by its mechanical behaviour. As first step towa...

In many of our everyday and professional routines, we rely on knowledge we gather from the auditory feedback of physical interactions. In an attempt to facilitate some of these listening practices (particularly percussion), we introduce a hear-through system for intra-stimulus Auditory Contrast Enhancement (ACE) in real time. Plausible spectral ACE...

This contribution considers how delay alterations of a median plane reflection influence the vertical auditory movement. Depending on the excitation signal we could show two partly contrasting effects dominating our perception: For broadband noise signals a delay modification between the leading direct sound and the lagging reflection yields spectr...

In the context of binaural audio, externalization refers to the sensation of virtual sound sources being located outside of the listener's head. Binaural reproduction using anechoic head-related impulse responses is known to suffer from poor externalization. The degree of externalization can be increased by reverberation, as contained in binaural r...

Every day, we rely on the information that is encoded in the auditory feedback of our physical interactions. With the goal to perceptually enhance those sound characteristics that are relevant to us-especially within professional practices such as percussion and auscultation-we introduce the method of real-time Auditory Contrast Enhancement (ACE)....

Like audification, auditory graphs maintain the temporal relationships of data while using parameter mappings to represent the ordinate values. Such direct approaches have the advantage of presenting the data stream ‘as is’ without the imposed interpretations or accentuation of particular features found in indirect approaches. However, datasets can...

Wir leben in einer visuell dominierten Kultur. Der tägliche Umgang mit Bildern ist uns vertraut, ihre Wirkungsmacht durch einen distanzierten Blick durchschaubar. Klang hingegen wird als Informationsträger, der über die dynamischen Zustände unserer Umwelt Auskunft gibt und uns hinter die Kulissen der Begrenzungsflächen von Objekten hören lässt, neg...

Compact spherical loudspeaker arrays are used to produce sound sculptures in electroacoustic music by modal beam-forming that orchestrates the wall reflections in the given space.Performance practice predominantly uses beams in the horizontal plane as they most effectively produce auditory objects via lateral reflections on unobstructed, close-enou...

Ambisonics has been widely adopted for conveying immersive audio experiences via headphone-based sound scene reproduction. It is well known, however, that the inherent reduction of spatial resolution of order-limited Ambisonic scenes leads to blurred source images, reduced spaciousness and direction-dependent timbral artifacts when rendered for bin...

SysSon is a sonification platform originally developed in collaboration with climatologists. It contains a domain-specific language for the design of sonification templates, providing abstractions for matrix input data and accessing it in real-time sound synthesis. A shortcoming of the previous version had been the limited breadth of transformation...

Auditory augmentation has been proposed as a specific, ambient sonification method. This paper describes an interdisciplinary workshop exploring this method by designing prototypes. Three of the prototypes are presented and discussed. Concluding on the workshop's results, the authors suggest a broader definition and deduce limitations of auditory a...

Sources from the frontal direction are still particularly challenging in binaural reproduction, as there are virtually no interaural time- and level differences. The perceived image of a binaural reproduction typically suffers from a vertical mislocalization and in-head localization. In the literature, different reasons for this problem can be foun...

Interactions with physical objects usually evoke sounds, i.e., auditory feedback that depends on the interacting objects (e.g., table, hand, or pencil) and interaction type (e.g., tapping or scratching). The continuous real-time adaptation of sound during interaction enables the manipulation/refinement of perceived characteristics (size, material)...

Raising awareness about how alarm sounds are perceived and evaluated by an individual in traffic scenery is important for developing new alarm designs, as well as for improving existing ones. Bearing a positive contribution to road safety, cyclists and pedestrians especially can benefit from appropriate alarming bell and horn sounds. Primarily, the...

Efficient feedback on energy consumption is regarded as one step towards a more sustainable lifestyle. Sonification is very apt to convey such information continuously in an ambient and effective way. This paper presents a pilot system for sonifying the electric power consumption of an institute's kitchen. The reverberation of the kitchen is change...

(Open Access: https://doi.org/10.1121/1.5040489) Binaural rendering of Ambisonic signals is of great interest in the fields of virtual reality, immersive media, and virtual acoustics. Typically, the spatial order of head-related impulse responses (HRIRs) is considerably higher than the order of the Ambisonic signals. The resulting order reduction o...

A method for acoustic scene playback comprises: providing recording data comprising microphone signals of one or more microphone setups positioned within an acoustic scene and microphone metadata of the one or more microphone setups, wherein each of the one or more microphone setups comprises one or more microphones and has a recording spot which i...

Sonification and audification create auditory displays of datasets. Audification translates data points into digital audio samples and the auditory display's duration is determined by the playback rate. Like audification, auditory graphs maintain the temporal relationships of data while using parameter mappings (typically data-to-frequency) to repr...

We, the authors, wish to make the following corrections to our paper [...]

Typically, the frequency-dependent transformation matrix to convert the signals of a spherical or circular microphone array to Ambisonic signals is obtained by a norm-constrained least-squares approach, where either modelled or measured microphone responses are used. These methods do not enforce orthonormality of the obtained directivity patterns,...

We present the evaluation of a sonification approach for the acoustic analysis of tremor diseases. The previously developed interactive tool offers two methods for sonification of measured 3-axes acceleration data of patients' hands. Both sonifications involve a bank of oscillators whose amplitudes and frequencies are controlled by either frequency...

The directivity of a sound source in a room influences the D/R ratio and thus the auditory distance. This study proposes various third-order beampattern pattern designs for a precise control of the D/R ratio. A comprehensive experimental study is conducted to investigate the hereby achieved effect on the auditory distance. Our first experiment aura...

A sound signal processing apparatus including a plurality of microphones, where each microphone is configured to receive the sound signal from the target source, a processor configured to estimate a first power measure on the basis of the sound signal from the target source received by a first microphone of the microphones and a second power measur...

[open access: http://www.mitpressjournals.org/doi/pdf/10.1162/COMJ_a_00396] The icosahedral loudspeaker (IKO) is able to project strongly focused sound beams into arbitrary directions. Incorporating artistic experience and psychoacoustic research, this article presents three listening experiments that provide evidence for a common, intersubjective...

We introduce an interactive sonification approach for the discrimination of tremor diseases. Following up to our previous research, we developed two new sonification methods of measured 3-axes acceleration data of patient’s hands. Prior to sonification, the data is conditioned by Principal Component Analysis (PCA) in order to separate translational...

This article investigates the accuracy with which listeners can identify the spatial extent of distributed sound sources. Either the complementary frequency bands comprising a source signal or the individual grains of a granular synthesis-based stimulus were distributed directly on discrete loudspeakers. Loudspeakers were arranged either on the hor...

The aim of immersive teleconferencing is to convey a realistic sound field impression to a remote participant. To this end, the spatial distribution of talkers as well as room information needs to be captured by the near-end system and accurately reproduced on the far-end. We consider a setup where high speech quality is obtained by means of severa...

We introduce SysSon, a platform for the development and application of sonification. SysSon aims to be an integrative system that serves different types of users, from domain scientists to sonification researchers to composers and sound artists. It therefore has an open nature capable of addressing different usage scenarios. We have used SysSon bot...

We present a sonification method that blends between audification and auditory graphs which we call ”Augmented Audification”. It is based on a combination of single-side-band modulation and a pitch modulation of the original data stream. Benefits include the flexible adjustment of the sonification’s frequency range to the human hearing range and th...

This contribution presents active sound generation (ASG) for interior sound enhancement to assist or improve sound feedback in either down-sized combustion engines or electric engines. It reports evaluation results from two studies about the description of engine sounds and the influence of sound feedback on driving behavior. Preliminary results in...

The engine sound power is a typical benchmark of combustion engines for vehicles, as it delivers a rough overall estimation of how loud an engine could be when built into a car. The grade 1 procedure for simultaneous sound power measurement considers 20 microphone positions around the engine in an anechoic room, and an engineering (grade 2) procedu...

Digital active noise control (ANC) for headphones usually has to predict the noise because of the latency of common audio converters. In adaptive feedback ANC, the prediction is based on the noise that entered the headphone. This noise is low-pass filtered because of the physical barrier of the ear cups. In this study, this low-pass characteristic...

Sonifications translate from a domain science to the auditory perception, thus also mediate usually between scientists of a given domain and sound experts. To make this mapping more explicit and less prone to misunderstandings, a sonification operator has recently been suggested. If the domain science communicates with mathematical terms, it is str...

The newly started research project SysSon (http://sysson.kug.ac.at) will develop a systematic procedure to develop sonifications, and test the procedure with climate data. The SysSon approach addresses the relevant obstacles that are met when introducing sonification in a new scientific domain: the cultural bias, usability and technical issues. Thi...

Chirping Stars is a tape piece made of the sonification of Twitter data. A snapshot of the popularity of musicians, randomly drawn in March 2012, yielded eight of the most popular stars at that time. Data of their Twitter followers shows the involvement of rapidly evolving fans of the artists on social media. The sonic interpre-tation of this devel...