Thesis

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Evalution of Surround Sound Setups based on Ambisonic Room Impulse Response Measurements

Authors Hoffbauer, E.
Year 2021
Thesis Type Master's thesis
Topic Spatial Audio
Keywords 3D sound
Abstract An exact and immersive spatial reproduction of audio signals is affected by multiple parameters, e.g., the influence of the acoustics of playback room, loudspeaker setup and signal processing algorithms. In this master thesis, approaches for the evaluation of surround sound setups are examined in regard of their auditory properties, including source localisation and source width, timbre preservation and direct-to-diffuse ratio. The measurement of multiple Ambisonic room impulse response enables the distinct description of the playback setup and the influence of the room, in which it is placed. Based on these impulse responses different sound reproduction methods on this measured system can be simulated digitally and evaluated without any additional measurements. Within the scope of this work existing quality criteria are tested on their suitability and, if needed, adapted or newly developed.
Supervisors Frank, M., Höldrich, R.
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Under Pressure: An Interactive Appropriation of Helmut Lachenmann’s Pression

Authors Questa, B.
Year 2021
Thesis Type Master's thesis
Topic Interaction Design
Keywords audiovisuell, Game, interaction
Abstract Under Pressure is an interactive appropriation of Helmut Lachenmann´s 1969 work for solo cello, Pression. It portrays the original score as a “2D Platformer” video game, wherein a user controlled avatar collides with elements in order to trigger a variety of sound events. This corresponding written part examines the ideological and philosophical background of appropriation and its relation to larger movements such as modernism and post-modernism. The first section explores the figure of Helmut Lachenmann and his relation to modernism, the second section on appropriation and its relation to postmodernism, and finally the last section examines Under Pressure from a theoretical standpoint, where Under Pressure is framed as a form of artistic research as it proposes interactive appropriation as a way of both researching and experiencing the original work in a new way.
URL https://phaidra.kug.ac.at/o:109115
Supervisors Eckel, G.
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Bodily Experience in Stage Arts

Authors Lee, D.
Year 2021
Thesis Type Master's thesis
Topic Embodiment
Keywords Embodiment, composition, Performance
Abstract This thesis summarizes recent research on diverse aspects of bodily perception in the author's stage works. In stage arts, the idea of bodily perception may possess an ambiguity in its definition due to the complexity of the human mind. To be precise, it may not merely consider a tactile stimulus on the skin or other organs in a live presentation. By focusing on the analysis of the author’s recent stage works, where multiple human senses have been examined in various manners, an attempt of categorizing the stimuli, demonstrating technical methods, and defining the aesthetics will be made.
Supervisors Ciciliani, M.
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Speech Signal Enhancement for loose-fit in-ear headphones

Authors Merz, P.
Year 2021
Thesis Type Master's thesis
Topic Audio Signal Processing
Keywords acoustics, microphone arrays, source and receiver directivity, directional microphones, directivity, signal processing
Abstract In-Ear headphones that can be used for telephony often have two microphones on the outside to enhance the user's speech signal by means of beamforming. If such an earphone also has hybrid active noise cancellation, it will also contain a third microphone on the inside, facing the ear canal. The aim of this thesis is to construct a beamforming system from the inside microphone and only one outside microphone, reducing the number of required microphones on such an earphone to two. To do so the general properties of first order microphone arrays and the attenuation of the signal arriving at the inside microphones are studied and measured. Based on the results an adaptive system is designed which compensates this attenuation for arbitrary earphone wearing conditions and maximizes the noise suppression by steering the beam pattern.
Supervisors Sontacchi, A.
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Modeling the Perception of Directional Sound Sources in Reverberant Environments

Authors Wendt, F.
Year 2021
Thesis Type Doctoral thesis
Topic Spatial Audio
Keywords auditory perception, psychoacoustics, directivity, perceptional model, binaural
Abstract The perception of sound in rooms is in uenced by the room acoustics. Depending on geometrical properties and texture of the room, a direct sound is followed by multiple re ections. For standard surrounding audio reproduction systems, the in uence of re ections on the perception is well studied. Recent developments allow more particular constellations and compact loudspeaker arrays with highly pronounced variable directivity patterns that excite wall re ections from a single point in the room to spatialize auditory events. However, their prediction in space mostly fails when standard localization models are used. This is because the underlying psychoacoustic principles are di erent from those known for standard spatialization systems. This doctoral thesis investigates perceptions elicited by the sound eld of a directional sound source in a room. Starting from auditory events evoked by a few precisely controlled sound instances examined in the laboratory, the aim of this work is to understand what perceptions are formed by the interaction of direct sound and its re ections. This bottom-up approach allows the development of models of perception building upon the measurements from the di erent stages of experimental complexity.
URL https://phaidra.kug.ac.at/o:108845
Supervisors Höldrich, R., Eckel, G., Dau, T.
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Variable-Orientation Auralization based on Room Response Measurements Involving Directivity

Authors Zaunschirm, M.
Year 2021
Thesis Type Doctoral thesis
Topic Spatial Audio
Keywords 3D sound, Ambisonics, auditory perception, binaural
Abstract An interactive and exible measurement-based auralization of an acoustic scenery bene ts from a separation into source-, room-, and receiver-dependent modules. This thesis presents a room description that facilitates such a modularity: the sourceand- receiver-directional Ambisonics room impulse response (SRD ARIR) capture and processing approach. In its most hardware-ecient implementation, the SRD ARIR relies on a small set of RIRs measured between a rst-order source and a rst-order receiver. In order to facilitate the auralization of sources with higher-order directivity, the Ambisonic spatial decomposition method (ASDM) is employed to enhance the directional resolution, i.e. to upscale the rst-order resolution of the measurements to higher orders. In the Ambisonics domain, the SRD ARIR interfaces seamlessly with the source and receiver directivities, which are typically available in Ambisonics as well. On the receiver side, this thesis presents perpetually motivated modi cations of the head-related transfer functions (HRTFs) that radically improve binaural rendering of Ambisonic signals. The methods either employ a frequency-dependent HRTF time alignment in pre-processing or use a magnitude-least-squares optimization where a phase-match at high frequencies is disregarded in favor of a magnitude match. Both renderers optionally include an interaural covariance correction that enforces optimal rendering of di use elds with only small impact when rendering particular free elds. Results from the presented listening experiments indicate that already an order of three allows for high-quality rendering. Measurement-based auralization does not exclusively rely on Ambisonics. Especially if modularity is not required, auralization based on multiple-orientation binaural room impulse responses (MOBRIRs) is a popular alternative. This thesis discusses the optimal MOBRIR resolution that allows for high-quality variable-orientation rendering while keeping the measurement e ort low. The results from listening experiments comparing various orientation resolutions indicate that the optimum is found for a resolution of 15 or ner. The proposed SRD ARIR method is perceptually evaluated in listening experiments where a MOBRIR-based auralization is employed as a reference condition. For both the MOBRIR- and the SRD ARIR-based auralization, the icosahedral loudspeaker array (IKO) was employed as directional source of well-studied perceptual e ects. The results of the listening experiments indicate results of similar quality when comparing the proposed SRD ARIR method to alternative rendering methods, when using measurements taken in the same acoustic environment.
URL https://phaidra.kug.ac.at/o:108846
Supervisors Höldrich, R., Eckel, G., Spors, S.
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Filmische Geräusch Landschaften

Authors Pichler, K.
Year 2021
Thesis Type Master's thesis
Topic Sound and Space
Abstract Contemporary film sound is highly dependent on the possibilities of post-synchronization. Physical sites as acoustic environments are often entirely reconstructed in audio post-production. The actual site-specific soundscape with its acoustic properties and its relation to the moment of filming seems to have therefore become obsolete. The use of site-specific sounds in film is critically examined on the basis of various concepts from film theory. Their conventional role in sound design is questioned. Based on theoretical analysis as well as practical experiments the creative potential of site-specific sounds is demonstrated. A cinematic approach is illustrated that ascribes an essential creative role to site-specific environmental sounds in film.
URL https://phaidra.kug.ac.at/o:108950
Supervisors Gründler, J.
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Investigation of Air Noise in Micro Loud-Speaker Systems

Authors Berghold, P.
Year 2021
Thesis Type Master's thesis
Topic Audio Signal Processing
Abstract Micro-loudspeaker systems suffer from the growing requirement for higher sound pressures levels, while their membrane area should decrease. Therefore, an exceeding membrane excursion, especially at low frequencies, is required. These excursions are physically related to the introduced air velocity in front of the membrane. The resulting high velocity is the cause of unwanted noise in sound ports, due to turbulences and vortex shedding in boundary layers and port edges. Standard parameters like the total harmonic distortion and compression fail to give a clear understanding if port noise is present or not. This work has the aim to define proper measurement conditions and identify a fingerprint/indicator for port noise caused in micro speaker systems. The findings will be related to the research done on port noise in bass reflex systems and validated with CFD simulations.
Supervisors Sontacchi, A.
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Der Einsatz von konkretem Klangmaterial in unterschiedlichen musikalischen Kontexten, ausgehend von Pierre Schaeffers „Musique concrète“

Authors Müller, L.
Year 2020
Thesis Type Bachelor's thesis
Topic Sound and Space
URL https://phaidra.kug.ac.at/o:108507
Supervisors Eckel, G.
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Block-oriented modeling of nonlinearities in electro-acoustical transducers

Authors Glattfelder, K.
Year 2020
Thesis Type Audio Engineering project
Topic Audio Signal Processing
Keywords audio recording and reproduction, signal processing
Abstract Electro-acoustical transducers, or simply speakers and microphones, are essentially omnipresent throughout everybody's life. The properties and behaviors of these transducers can be analyzed and identified to create models which are used to further refine the quality of the sound or to digitally simulate the identified speaker (e.g. the cabinet of a guitar amplifier with its distinctive sound). One particular aspect of the transducer is its nonlinear behavior, that tends to be especially prominent when operating the speaker at high sound pressure levels (high displacement of the membrane). This “distortion” diminishes the sound quality and can create additional harmonic components that were not originally part of the signal. Although the total amount of the harmonic distortion can be quantified, it is not possible to further characterize the distortion with the conventional identification processes since they only capture the linear behavior. The goal of the current study is creating a python script for block-oriented modeling of nonlinearities in electro-acoustical transducers with Wiener or Hammerstein systems.
Supervisors Höldrich, R.
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Analysis and visualization of bell-ringing

Authors Holzmüller, F.
Year 2020
Thesis Type Audio Engineering project
Topic Audio Signal Processing
Abstract Bell-ringing is a fundamental part of ecclesiastical rites. The aim of this interdisciplinary project involving the long night of churches and the Akademie Graz is to provide a visualization of peal, especially for hearing impaired persons. In a first step, an analysis tool is created. Therefore spectral and temporal features are analyzed including fundamental frequency, harmonic structure, rhythmical motives and dynamic progression. In a next step, a real-time visualization based upon the found parameters is created. A realization of this project is planned for the next long night of churches in Graz.
Supervisors Sontacchi, A.
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Sensor shield and fusion algorithm evaluation of DIY Attitude and Heading Reference Systems (AHRS)

Authors Berghold, P.
Year 2020
Thesis Type Audio Engineering project
Topic Spatial Audio
Keywords 3D sound, Ambisonics, binaural, Hardware, Human Computer Interaction (HCI), Motion Capture, signal processing
Abstract Head orientation estimation is an important task for plausible perception of virtual acoustics. To gain a reliable 3D acoustic scene via headphone playback, tracking of the listener's head movements is a necessary feature. Micro Electro Mechanical Systems (MEMS) oer a cheap and su cient possibility to track such movements, but lack in accuracy. This work evaluates state of the art sensor shields (BNO055, NXP 9DOF and MPU9250) and fusion algorithms for the de- sign of an attitude and heading reference system (AHRS) on the Arduino platform. The orientation estimation of the sensors is compared to an optical tracking system (Optitrack Flex 13). It is shown that all sensors can achieve su cient orientation estimation with the right fusion algorithm and proper calibration. Their perfor- mance diers in the robustness against magnetic distortions and gyroscope bias drift. Nevertheless the BNO sensor outperforms the others with its ease of use as it has an onboard sensor fusion.
URL https://phaidra.kug.ac.at/o:108232
Supervisors Rudrich, D.
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Repeated Pitch-shifting for Frequency Discretization as an Artistic Effect for Speech Signals

Authors Planton, M.
Year 2020
Thesis Type Audio Engineering project
Topic Audio Signal Processing
Keywords Computermusic and Elektronic Music, frequency estimation, sound synthesis
Abstract Pitch-shifting effects have been used for a long time, but there are still new innovations to the employed algorithms for fundamental tone analysis (pitch-tracking) and synthesis of a frequency shifted audio signal (pitch-shifting). This project starts with the research on the contemporary pitch-tracking and pitch-shifting algorithms literature, to develop a frequency discretizing pitch-shifting algorithm for monophonic speech signals. Strategies and techniques of the specific design for the effects implementation are discussed. Finally the artistic potential of the effect is evaluated in several applications. So a monophonic speech signal is discretized according to certain pitch scales. The center of this study is the outcome of the repeated application of this audio effect and which possibilities it offers.
Supervisors Höldrich, R.
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Automatic DOA estimator for spatial music recordings

Authors Maurer, S., Beck, S.
Year 2020
Thesis Type Audio Engineering project
Topic Audio Signal Processing
Keywords 3D sound, Ambisonics, B-format, Higher-Order Ambisonics (HOA), microphone arrays, signal processing, Spatial Audio, Software
Abstract The orientation in a room and its parameters are important knowledge when it comes to ambisonic musical performances. In this project an audio plug-in is developed which enables performers to estimate the position of their instruments in a room related to an ambisonic microphone array. Two different approaches of this task will be examined. Both are based on the same idea of building an intensity vector for determining the direction of arrival of the sound sources. One approach is to calculate the intensity vector of the whole array signal in the frequency domain which is filtered with a mask to separate the different instrument signals. The second approach is to calculate the intensity vector of an ambisonic room impulse response. The room impulse response is extracted from the musical signals with the help of a LMS-algorithm. With this room impulse response it is also possible to find room parameters like reverberation time and the dimensions of the room. Since it is a difficult task to make a stable and real time compatible algorithm for this, it will not find place in the plug-in but different methods to determine those parameters will be evaluated.
Supervisors Frank, M., Rudrich, D.
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Multi-Perspective Scene Analysis from Tetrahedral Microphone Recordings

Authors Blochberger, M.
Year 2020
Thesis Type Master's thesis
Topic Spatial Audio
Keywords audio recording and reproduction, B-format, Higher-Order Ambisonics (HOA), signal processing, Spatial Audio
Abstract Convincing immersion in virtual reality requires to enable the user to engage in interactive listening within three-dimensional audio scenes. To achieve a realistic listening experience, the acoustic perspective and orientation has to be real-time controlled with the own body movements. This thesis addresses the task of presenting an interpolated variable perspective to an interacting listener, while the original audio scene is recorded simultaneously at only a few static perspectives. The scene is decomposed into localizable sound objects and a residual signal for the variable-perspective interpolation. Information regarding localizable objects is extracted from a probability map that is composed from the directions detected by the collective of the available single perspectives. This work proposes a particle-filter-based approach for a continuous position estimation of sound objects. The particle filter uses the probability map to estimate a continuous trajectory for each sound object in the scene. The rendering approach extracts signals from the recording for each localized sound object according to its estimated trajectory and embeds it relative to the virtual listener into the residual signal.
URL https://phaidra.kug.ac.at/o:104549
Supervisors Zotter, F., Höldrich, R.
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Fast measurement of HRTFs in a loudspeaker-array system

Authors Blöcher, C.
Year 2020
Thesis Type Audio Engineering project
Topic Audio Signal Processing
Keywords HRTF Measurement, Music Information Retrieval, binaural
Supervisors Sontacchi, A., Majdak, P.
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EarSCAPE

Authors Cladders, J.
Year 2020
Thesis Type Bachelor's thesis
Topic Spatial Audio
Keywords Audio, binaural, Spatial Audio, Game
Abstract EarSCAPE is an audio-game in the genre of so called escape games. Usually the player has to succeed in di erent tasks to nally escape from one or more rooms. In EarSCAPE the player is trapped in a single room with only one exit and has to follow di erent auditive cues to successfully escape the room within a given time. There is no visual support. The auditive orientation is based on binaural spatialization using Head Related Transfer Functions (HRTFs), so the use of headphones is obligatory. The implementation was done in Pure Data (Pd) in a way, that it is accessible to the user to create own levels by placing audio events in a room and assigning own samples to it. For its non-visual output, the game is also playable for people without the ability to see.
URL https://phaidra.kug.ac.at/o:108229
Supervisors Zmölnig, J.
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3D Audio Sound Branding

Authors Sternbauer, M.
Year 2020
Thesis Type Master's thesis
Topic Audio Signal Processing
Abstract Recent developments in 3D audio technology have not only attracted more attention from a broader audience, but also enable easier integration into everyday life. This applies to both binaural playback and the 3D audio speaker systems. Furthermore, it creates the opportunity for acoustic brand communication (sound branding) to establish a new touchpoint and experience for customers. This master thesis explores the creative possibilities and difficulties that emerge. In the theoretical part the directional and distance perception of the human hearing system is explained in acoustic and psychoacoustic terms. The visual component in hearing perception is also addressed. In the practical part the production process of several sound logos for the IKO, a 20-sided speaker system, is documented. Different movement patterns and sound objects were created using typical sound materials. These were examined by test persons for their comprehensibility and impact. The listening tests confirm not only a spectral dependency in the localization but also differences in the perception of the spatial dimension. Besides certain design criteria, factors influencing the subjective assessment could also be found. In addition, the influence of visual cues on more complex auditory objects is confirmed.
URL https://phaidra.kug.ac.at/o:108231
Supervisors Sontacchi, A.
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Exemplarische Untersuchung eines Quellseparationsalgorithmus

Authors Kaiser, L.
Year 2020
Thesis Type Bachelor's thesis
Topic Audio Signal Processing
Keywords Music Information Retrieval, signal processing, Software
URL https://phaidra.kug.ac.at/o:108230
Supervisors Sontacchi, A.
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Development and Evaluation of an Algorithm for the Enhancement of First-Order Ambisonic Impulse Responses

Authors Hoffbauer, E.
Year 2020
Thesis Type Audio Engineering project
Topic Spatial Audio
Keywords Ambisonics, B-format, Higher-Order Ambisonics (HOA), microphone arrays
Abstract For the immersive sonic representation of a room, e.g. with a convolution reverb, it is useful to measure an Ambisonic room impulse response (ARIR) with a microphone array. This is usually performed in First Order Ambisonics (FOA), out of practical and monetary reasons. However from the playback perspective Higher Order Ambisonics (HOA) have many advantages, like a sharper resolved representation of directions and depth, which results all-in-all in a recording subjectively perceived as very natural sounding. As follows a interesting approach for improvement is to develop algorithms that enhance recorded signals of lower order in a realistic way as possible to a set of HOA signals and combine in that way the advantages of both the recording and playback domain. In the first part of this project thesis an algorithm based on the principles of the Spatial Decomposition Method (SDM) is developed, that decodes via the estimation of the pseudo-intensity vector multiple directions of a given first-order and encodes them again in any desired order. In the second part the results of this algorithm are compared to other known algorithms in a listening test and possible advantages and drawbacks are investigated.
Supervisors Frank, M.
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Spherical-harmonic representation in the spatially oriented format for acoustics (SOFA)

Authors Perfler, F.
Year 2020
Thesis Type Audio Engineering project
Topic Spatial Audio
Keywords 3D sound, Higher-Order Ambisonics (HOA), acoustics, spherical harmonics, acoustic source localization
Abstract follows
Supervisors Sontacchi, A., Majdak, P.
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Akustische Untersuchung von Aktoren als Lautsprecherersatz im Fahrzeughimmel

Authors Kocher, L.
Year 2020
Thesis Type Master's thesis
Topic Spatial Audio
Keywords psychoacoustics, 3D sound
Abstract follows
Supervisors Frank, M., Höldrich, R.
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New Multi-Touch Instrument With Visual Feedback

Authors Bradl, H.
Year 2020
Thesis Type Audio Engineering project
Topic Audio Signal Processing
Keywords freie Tonskalen, Computer Music, Computermusic and Elektronic Music, sound synthesis
Abstract The aim of this project is the development of a polyphonic multi-touch instrument which is not limited to a traditional twelve-tone scale. Instead it should allow scales with freely selectable resolution, i.e. notes per octave. Since it's not possible to apply classical music theory when using alternative scales, the instrument should give the musician visual hints which note combinations could make sense.
Supervisors Zotter, F.
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Kommunizieren mit Stille

Authors Breuner, E.
Year 2020
Thesis Type Master's thesis
Topic Sound and Space
Keywords Sound Design, sparsity
Abstract Silence (Quietness) is an ambivalent concept that cannot make use of a general definition. It is accompanied by a whole range of interpretations, not exclusively a form of interpretation. The master's thesis takes up this multifaceted concept and considers silence (quietness) as a means of sound design in film. In this sense, it is the task of the master's thesis to classify silence (quietness) according to the context in a meaningful way and to make it comprehensible as a narrative stylistic device. Silence (Quietness) can appear in different ways; depending on the genre, sound design will pursue different creative interests. Although not directly related to it, the idea of the master's thesis is to encourage listening, like Murray Schafer once did, to discover silence and to fathom its dramaturgical potential.
URL https://phaidra.kug.ac.at/o:108856
Supervisors Ciciliani, M., Groß-Vogt, K.
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Optimally Curved Arc Source

Authors Gölles, L.
Year 2020
Thesis Type Master's thesis
Topic Spatial Audio
Keywords acoustics, Ambisonics, directivity, Spatial Audio, audio reproduction
Abstract The properties of sound systems for three-dimensional sound material are already relatively well understood, as long as the size of the audience remains manageable, i.e. up to about 200 people. For example, the sweet area size for Ambisonic playback systems as usable audience area was examined for direct sound and reverberation. However, such sound systems are already reaching their limits. The sound propagation over longer distances are hardly taken into account by the know studies. According to the current state of the art, sound transmission over large distances is mostly solved by the use of a progressively curved line-source loudspeaker array. This thesis deals with the realization of optimally curved line-source loudspeaker arrays for immersive sound reinforcement in order to guarantee an optimally enveloping/immersive soundscape for the majority of the audience. To this end, this work elaborates a theory of optimally curved line source arrays at different heights and investigates the achievable sound pressure level contour depending on the distance, on the one end. On the other hand, the new theory is evaluated in concluding practical experiments.
Supervisors Zotter, F., Höldrich, R.