Papers by Asteris Zacharakis
A study on the verbal attributes of musical timbre was conducted in an effort to identify the mos... more A study on the verbal attributes of musical timbre was conducted in an effort to identify the most significant semantic descriptors and to quantify the association between prominent timbral aspects and several categorical properties of environmental entities. A verbal attribute magnitude estimation (VAME) type of listening test in which participants were asked to describe 23 musical sounds using 30 Greek adjectives together with verbal terms of their own choice was designed and conducted for this purpose. Factor and Cluster Analysis were performed on the subjective evaluation data in order to shed some light on the relationships between the adjectives that were proposed and to conclude to the number and quality of the salient perceptual dimensions required for the description of this set of sounds.
The General Chord Type (GCT) representation is appropriate for encoding tone simultaneities in an... more The General Chord Type (GCT) representation is appropriate for encoding tone simultaneities in any harmonic context (such as tonal, modal, jazz, octatonic, atonal). The GCT allows the re-arrangement of the notes of a harmonic sonority such that abstract idiom-specific types of chords may be derived. This encoding is inspired by the standard roman numeral chord type labelling and is, therefore, ideal for hierarchic harmonic systems such as the tonal system and its many variations; at the same time, it adjusts to any other harmonic system such as post-tonal, atonal music, or traditional polyphonic systems. In this paper the descriptive potential of the GCT is assessed in the tonal idiom by comparing GCT harmonic labels with human expert annotations (Kostka & Payne harmonic dataset). Additionally, novel methods for grouping and clustering chords, according to their GCT encoding and their functional role in chord sequences, are introduced. The results of both harmonic labelling and functional clustering indicate that the GCT representation constitutes a suitable scheme for representing effectively harmony in computational systems.
Conceptual blending is a cognitive theory whereby elements from diverse, but structurally-related... more Conceptual blending is a cognitive theory whereby elements from diverse, but structurally-related, mental spaces are 'blended' giving rise to new conceptual spaces. This study focuses on structural blending utilising an algorithmic formalisation for conceptual blending applied to harmonic concepts. More specifically, it investigates the ability of the system to produce meaningful blends between harmonic cadences, which arguably constitute the most fundamental harmonic concept. The system creates a variety of blends combining elements of the penultimate chords of two input cadences and it further estimates the expected relationships between the produced blends. Then, a preliminary subjective evaluation of the proposed blending system is presented. A pairwise dissimilarity listening test was conducted using original and blended cadences as stimuli. Subsequent multidimensional scaling analysis produced spatial configurations for both behavioural data and dissimilarity estimations by the algorithm. Comparison of the two configurations showed that the system is capable of making fair predictions of the perceived dissimilarities between the blended cadences. This implies that this conceptual blending approach is able to create perceptually meaningful blends based on self-evaluation of its outcome.
Conceptual blending is a powerful tool for computational creativity where, for example, the prope... more Conceptual blending is a powerful tool for computational creativity where, for example, the properties of two harmonic spaces may be combined in a consistent manner to produce a novel harmonic space. However, deciding about the importance of property features in the input spaces and evaluating the results of conceptual blending is a nontrivial task. In the specific case of musical harmony, defining the salient features of chord transitions and evaluating invented harmonic spaces requires deep musicological background knowledge. In this paper, we propose a creative tool that helps musicologists to evaluate and to enhance harmonic innovation. This tool allows a music expert to specify arguments over given transition properties. These arguments are then considered by the system when defining combinations of features in an idiom-blending process. A music expert can assess whether the new harmonic idiom makes musicological sense and re-adjust the arguments (selection of features) to expl...
This chapter presents the CHAMELEON melodic harmonisation assistant that learns different aspects... more This chapter presents the CHAMELEON melodic harmonisation assistant that learns different aspects of harmony from expert-annotated data, blends learnt harmonies from different idioms using the COINVENT framework and harmonises user-given melodies. The learnt harmonic elements include chord types, chord transitions, cadences and bass voice leading, while blending is employed on the level of chord transitions. A methodology that integrates chord transition blending is utilised for constructing a compound chord transition probability matrix that combines information of two initial learnt harmonic idioms. This chapter also presents the key-findings of empirical studies on the perception of blends, focusing initially on results obtained from cadence blending and afterwards on the output of the CHAMELEON system. The empirical evaluation of the CHAMELEON system was performed through tests that were specifically designed for evaluating blending; results indicate that the COINVENT framework ...
Acta Acustica united with Acustica, 2017
Studies of timbre are usually conducted in a"vacuum" of perfect silence. However, in the real-wor... more Studies of timbre are usually conducted in a"vacuum" of perfect silence. However, in the real-world, sounds are mostly heard in the presence of competing background noise. Aseries of pairwise dissimilarity listening tests on musically trained participants demonstrated howd i ff erent levels of background noise can cause rearrangement of timbre spaces. Furthermore, it wass hown that while spectral acoustic descriptors (e.g. spectral centroid or tristimulus values)seem robust under the presence of background noise, descriptors representing deviations from purely harmonic characteristics (e.g. inharmonicity)l ose their salience for the higher noise level. Such results suggest that studies of timbre may need to takebackground noise into account in order to enhance their validity for real world applications.
Journal of the Audio Engineering Society, 2016
This study presents a listening experiment designed to further examine the previously proposed lu... more This study presents a listening experiment designed to further examine the previously proposed luminance-texture-mass (LTM) model for timbral semantics. Thirty-two musically trained listeners rated twenty-four instrument tones on six predefined semantic scales, namely, brilliance, depth, roundness, warmth, fullness, and richness. The selection of this limited set of descriptors was based on previous exploratory work. These six semantic scales were analyzed through Principal Component Analysis (PCA) and Multidimensional Scaling (MDS) to produce two different timbre spaces. These timbre spaces were subsequently compared for configurational and dimensional similarity with the LTM semantic space and the direct MDS perceptual space obtained from the same stimuli. The results showed that the six selected semantic scales are adequately representing the LTM model and are fair at predicting the configurations of the sounds that result from pairwise dissimilarity ratings. However, our analysis indicates that the enhancement of the LTM model with a term related to percussiveness might constitute a valuable extension.
IFIP Advances in Information and Communication Technology, 2016
Conceptual blending when used as a creative tool combines the features of two input spaces, gener... more Conceptual blending when used as a creative tool combines the features of two input spaces, generating new blended spaces that share the common structure of the inputs, as well as different combinations of their non-common parts. In the case of music, conceptual blending has been employed creatively, among others, in generating new cadences (pairs of chords that conclude musical phrases). Given a specific set of input cadences together with their blends, this paper addresses the following question: are some musical features of cadences more salient than others in defining perceived relations between input and blended cadences? To this end, behavioural data from a pairwise dissimilarity listening test using input and blended cadences as stimuli were collected, thus allowing the construction of a 'ground-truth' human-based perceptual space of cadences. Afterwards, the salience of each cadence feature was adjusted through the Differential Evolution (DE) algorithm, providing a system-perceived space of cadences that optimally matched the ground-truth space. Results in a specific example of cadence blending indicated that some features were distinguishably more salient than others. This pilot study was a first step towards building self-aware blending systems and revealed that the salience of features in conceptual blending is an essential part for producing perceptually relevant blends.
IFIP Advances in Information and Communication Technology, 2016
How can harmony in diverse idioms be represented in a machine learning system and how can learned... more How can harmony in diverse idioms be represented in a machine learning system and how can learned harmonic descriptions of two musical idioms be blended to create new ones? This paper presents a creative melodic harmonisation assistant that employs statistical learning to learn harmonies from human annotated data in practically any style, blends the harmonies of two user-selected idioms and harmonises userinput melodies. To this end, the category theory algorithmic framework for conceptual blending is utilised for blending chord transition of the input idioms, to generate an extended harmonic idiom that incorporates a creative combination of the two input ones with additional harmonic material. The results indicate that by learning from the annotated data, the presented harmoniser is able to express the harmonic character of diverse idioms in a creative manner, while the blended harmonies extrapolate the two input idioms, creating novel harmonic concepts.
Music Perception: An Interdisciplinary Journal, 2014
A study of musical timbre semantics was conducted with listeners from two different linguistic gr... more A study of musical timbre semantics was conducted with listeners from two different linguistic groups. In two separate experiments, native Greek and English speaking participants were asked to describe 23 musical instrument tones of variable pitch using a predefined vocabulary of 30 adjectives. The common experimental protocol facilitated the investigation of the influence of language on musical timbre semantics by allowing for direct comparisons between linguistic groups. Data reduction techniques applied to the data of each group revealed three salient semantic dimensions that shared common conceptual properties between linguistic groups namely: luminance, texture, and mass. The results supported universality of timbre semantics. A correlation analysis between physical characteristics and semantic dimensions associated: i) texture with the energy distribution of harmonic partials, ii) thickness (a term related to either mass or luminance) and brilliance with inharmonicity and spec...
An algorithm that achieves independent modification of two low-level features that are correlated... more An algorithm that achieves independent modification of two low-level features that are correlated with the auditory perceptions of brightness and warmth was implemented. The perceptual validity of the algorithm was tested through a series of listening tests in order to examine whether the low-level modification was indeed perceived as independent and to investigate the influence of the fundamental frequency on the perceived modification. A Multidimensional Scaling analysis (MDS) on listener responses to pairwise dissimilarity comparisons accompanied by a verbal elicitation experiment, examined the perceptual significance and independence of the two low-level features chosen. This is a first step for the future development of a perceptually based control of an additive synthesizer.
IFIP Advances in Information and Communication Technology, 2016
Conceptual blending when used as a creative tool combines the features of two input spaces, gener... more Conceptual blending when used as a creative tool combines the features of two input spaces, generating new blended spaces that share the common structure of the inputs, as well as different combinations of their non-common parts. In the case of music, conceptual blending has been employed creatively, among others, in generating new cadences (pairs of chords that conclude musical phrases). Given a specific set of input cadences together with their blends, this paper addresses the following question: are some musical features of cadences more salient than others in defining perceived relations between input and blended cadences? To this end, behavioural data from a pairwise dissimilarity listening test using input and blended cadences as stimuli were collected, thus allowing the construction of a 'ground-truth' human-based perceptual space of cadences. Afterwards, the salience of each cadence feature was adjusted through the Differential Evolution (DE) algorithm, providing a system-perceived space of cadences that optimally matched the ground-truth space. Results in a specific example of cadence blending indicated that some features were distinguishably more salient than others. This pilot study was a first step towards building self-aware blending systems and revealed that the salience of features in conceptual blending is an essential part for producing perceptually relevant blends.
The General Chord Type (GCT) representation is appropriate for encoding tone simultaneities in an... more The General Chord Type (GCT) representation is appropriate for encoding tone simultaneities in any harmonic context (such as tonal, modal, jazz, octatonic, atonal). The GCT allows the re-arrangement of the notes of a harmonic sonority such that abstract idiom-specific types of chords may be derived. This encoding is inspired by the standard roman numeral chord type labelling and is, therefore, ideal for hierarchic harmonic systems such as the tonal system and its many variations; at the same time, it adjusts to any other harmonic system such as post-tonal, atonal music, or traditional polyphonic systems. In this paper the descriptive potential of the GCT is assessed in the tonal idiom by comparing GCT harmonic labels with human expert annotations (Kostka & Payne harmonic dataset). Additionally, novel methods for grouping and clustering chords, according to their GCT encoding and their functional role in chord sequences, are introduced. The results of both harmonic labelling and func...
ABSTRACT ‘Motion’, as expressed through high-level features of music, combined with mirror neuron... more ABSTRACT ‘Motion’, as expressed through high-level features of music, combined with mirror neuron (MN) system activation is studied in this article. The mechanism of MN involved in the perception of musical structures is seen as a means for cueing the learner on ‘known’ factors that can be used for his/her knowledge scaffolding. To explore such relationships, EEG recordings, and especially the Mu-rhythm over the sensorimotor cortex that relates to the activation of MN, were acquired and explored. An experiment was designed to provide the auditory and visual stimuli to two groups of subjects, advanced music students and non–musicians as a control subject group. The musician group’s response to ‘motion’, implemented by Modest Mussorgsky’s ‘Promenade’ and a corresponding video clip, was monitored. The acquired signals, after appropriate averaging in the time domain, were analyzed in the bifrequency domain, using bispectral analysis. Experimental results showed that motion inherent in high–level features of music, could be associated with Mu–rhythm modulation. Such modulation provoked by the MNs could cause bispectral fluctuations, especially when visual stimulation is combined with an auditory one. These results pave the way for further exploitation of the role of MNs in music and, in general, knowledge perception.
This study presents a listening experiment designed to further examine the previously proposed lu... more This study presents a listening experiment designed to further examine the previously proposed luminance-texture-mass (LTM) model for timbral semantics. Thirty-two musically trained listeners rated twenty-four instrument tones on six predefined semantic scales, namely, brilliance, depth, roundness, warmth, fullness, and richness. The selection of this limited set of descriptors was based on previous exploratory work. These six semantic scales were analyzed through Principal Component Analysis (PCA) and Multidimensional Scaling (MDS) to produce two different timbre spaces. These timbre spaces were subsequently compared for configurational and dimensional similarity with the LTM semantic space and the direct MDS perceptual space obtained from the same stimuli. The results showed that the six selected semantic scales are adequately representing the LTM model and are fair at predicting the configurations of the sounds that result from pairwise dissimilarity ratings. However, our analysis indicates that the enhancement of the LTM model with a term related to percussiveness might constitute a valuable extension.
Studies of timbre are usually conducted in a 'vacuum' of perfect silence. However, in the real-wo... more Studies of timbre are usually conducted in a 'vacuum' of perfect silence. However, in the real-world, sounds are mostly heard in the presence of competing background noise. A series of pairwise dissimilarity listening tests on musically trained participants demonstrated how different levels of background noise can cause rearrangement of timbre spaces. Furthermore, it was shown that while spectral acoustic descriptors (e.g. spectral centroid or tristimulus values) seem robust under the presence of background noise, descriptors representing deviations from purely harmonic characteristics (e.g. inharmonicity) lose their salience for the higher noise level. Such results suggest that studies of timbre may need to take background noise into account in order to enhance their validity for real world applications.
Music Perception: An Interdisciplinary Journal, 2015
‘Motion’, as expressed through high-level features of music, combined with mirror neuron (MN) sys... more ‘Motion’, as expressed through high-level features of music, combined with mirror neuron (MN) system activation is studied in this article. The mechanism of MN involved in the perception of musical structures is seen as a means for cueing the learner on ‘known’ factors that can be used for his/her knowledge scaffolding. To explore such relationships, EEG recordings, and especially the Mu-rhythm over the sensorimotor cortex that relates to the activation of MN, were acquired and explored. An experiment was designed to provide the auditory and visual stimuli to two groups of subjects, advanced music students and non–musicians as a control subject group. The musician group’s response to ‘motion’, implemented by Modest Mussorgsky’s ‘Promenade’ and a corresponding video clip, was monitored. The acquired signals, after appropriate averaging in the time domain, were analyzed in the bifrequency domain, using bispectral analysis. Experimental results showed that motion inherent in high–level...
Music Perception: An Interdisciplinary Journal, 2015
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Papers by Asteris Zacharakis