Dr Sven-Amin Lembke

Job: VC2020 Lecturer in Music and Audio Technology

Faculty: Technology

School/department: Leicester Media School

Research group(s): Music, Technology and Innovation Research Centre (MTIRC)

Address: Clephan Building 0.07B, De Montfort University, Leicester LE1 9BH, UK

T: +44 (0)116 207 8482

E: sven-amin.lembke@dmu.ac.uk

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Personal profile

Sven-Amin Lembke seeks to describe the experiences of creating, performing or listening to music, based on an interdisciplinary approach spanning musicology, acoustics and psychology, which informs both his teaching and research practice.

Research group affiliations

Music, Technology and Innovation Research Centre (MTIRC)

Publications and outputs

Hearing triangles: perceptual clarity, opacity, and symmetry of spectrotemporal sound shapes
Hearing triangles: perceptual clarity, opacity, and symmetry of spectrotemporal sound shapes Lembke, Sven-Amin In electroacoustic music, the spectromorphological approach commonly employs analogies to non-sonic phenomena like shapes, gestures, or textures. In acoustical terms, sound shapes can concern simple geometries on the spectrotemporal plane, for instance, a triangle that widens in frequency over time. To test the auditory relevance of such triangular sound shapes, two psychoacoustic experiments assessed if and how these shapes are perceived. Triangular sound-shape stimuli, created through granular synthesis, varied across the factors grain density, frequency and amplitude scales, and widening vs. narrowing orientations. The perceptual investigation focused on three auditory qualities, derived in analogy to the visual description of a triangle: the clarity of the triangular outline, the opacity of the area enclosed by the outline, and the symmetry along the vertical dimension. These morphological qualities seemed to capture distinct perceptual aspects, each linked to different acoustical factors. Clarity of shape was conveyed even for sparse grain densities, while also exhibiting a perceptual bias for widening orientations. Opacity varied as a function of grain texture, whereas symmetry strongly depended on frequency and amplitude scales. The perception of sound shapes could relate to common perceptual cross-modal correspondences and share the same principles of perceptual grouping with vision. The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.
Blending between bassoon and horn players: an analysis of timbral adjustments during musical performance
Blending between bassoon and horn players: an analysis of timbral adjustments during musical performance Lembke, Sven-Amin; Levine, Scott; McAdams, Stephen Achieving a blended timbre between two instruments is a common aim of orchestration. It relates to the auditory fusion of simultaneous sounds and can be linked to several acoustic factors (e.g., temporal synchrony, harmonicity, spectral relationships). Previous research has left unanswered if and how musicians control these factors during performance to achieve blend. For instance, timbral adjustments could be oriented towards the leading performer. In order to study such adjustments, pairs of one bassoon and one horn player participated in a performance experiment, which involved several musical and acoustical factors. Performances were evaluated through acoustic measures and behavioral ratings, investigating differences across performer roles as leaders or followers, unison or non-unison intervals, and earlier or later segments of performances. In addition, the acoustical influence of performance room and communication impairment were also investigated. Role assignments affected spectral adjustments in that musicians acting as followers adjusted toward a `darker' timbre, i.e., realized by reducing the frequencies of the main formant or spectral centroid. Notably, these adjustments occurred together with slight reductions in sound level, although this was more apparent for horn than bassoon players. Furthermore, coordination seemed more critical in unison performances and also improved over the course of a performance. These findings compare to similar dependencies found concerning how performers coordinate their timing and suggest that performer roles also determine the nature of adjustments necessary to achieve the common aim of a blended timbre. The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.
Acoustical correlates of perceptual blend in timbre dyads and triads
Acoustical correlates of perceptual blend in timbre dyads and triads Lembke, Sven-Amin; Parker, Kyra; Narmour, Eugene; McAdams, Stephen Achieving a blended timbre for particular combinations of instruments, pitches, and articulations is a common aim of orchestration. This involves a set of factors that this study jointly assesses by correlating the perceptual degree of blend with the underlying acoustical characteristics. Perceptual blend ratings from two experiments were considered, with the stimuli consisting of: 1)~dyads of wind instruments at unison and minor-third intervals and at two pitch levels, and 2)~triads of wind and string instruments, including bowed and plucked string excitation. The correlational analysis relied on partial least-squares regression, as this technique is not restricted by the number and collinearity of regressors. The regressors encompassed acoustical descriptors of timbre (spectral, temporal, and spectrotemporal) as well as ones accounting for pitch and articulation. From regressor loadings in principal-components space, the major regressors leading to substantial and orthogonal contributions were identified. The regression models explained around 90\% of the variance in the datasets, which was achievable with less than a third of all regressors considered initially. Blend seemed to be influenced by differences across intervals, pitch, and articulation. Unison intervals yielded more blend than did non-unison intervals, and the presence of plucked strings resulted in clearly lower blend ratings than for sustained instrument combinations. Furthermore, prominent spectral features of instrument combinations influenced perceived blend. The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.
The use of microphone level balance in blending the timbre of horn and bassoon players
The use of microphone level balance in blending the timbre of horn and bassoon players Lembke, Sven-Amin; Levine, Scott; de Francisco, Martha; McAdams, Stephen A common musical aim of orchestration is to achieve a blended timbre for certain instrument combinations. Its success has been shown to also depend on the timbral coordination between musicians during performance, which this study extends by adding the subsequent involvement of sound engineers. We report the results from a production experiment in which sound engineers mixed independent feeds for a main and two spot microphones to blend the timbre of pairs of bassoon and horn players in a two-channel stereo mix. The balance of microphone feeds can be shown to be affected by leadership roles between performers, the musical material, and aspects related to room acoustics and performer characteristics. Center for Interdisciplinary Research on Music Media and Technology (CIRMMT), McGill University
The role of spectral-envelope characteristics in perceptual blending of wind-instrument sounds
The role of spectral-envelope characteristics in perceptual blending of wind-instrument sounds Lembke, Sven-Amin; McAdams, Stephen Certain combinations of musical instruments lead to perceptually more blended timbres than others. Orchestration commonly seeks these combinations and can benefit from generalized acoustical descriptions of perceptually relevant features that allow the prediction of blend. Previous research on correlating such instrument-specific features with the perception of blend shows an important role of spectral-envelope characteristics, leaving unanswered, however, whether global or local characteristics are more important (e.g., spectral centroid or formant structure). This paper reports how wind instruments can be characterized through pitch-generalized spectral-envelope descriptions that exhibit their formant structure and how this is represented in an auditory model. Two experiments employing blend-production and blend-rating tasks study the perceptual relevance of formants to blend, involving dyads of a recorded instrument sound and a parametrically varied synthesized sound. Frequency relationships between formants influence blend critically, as does the degree of formant prominence. In addition, multiple linear regression relying primarily on local spectral-envelope characteristics explains 87% of the variance in blend ratings. A perceptual model for the contribution of spectral characteristics to perceived blend is proposed. Centre for Interdisciplinary Research in Music Media and Technology (CIRMMT), McGill University
Measuring the interaction between bassoon and horn players in achieving timbre blend
Measuring the interaction between bassoon and horn players in achieving timbre blend Lembke, Sven-Amin; Levine, Scott; de Francisco, Martha; McAdams, Stephen Our study investigates the interactive relationship between bassoon and horn players in achieving timbre blend during musical performance. The interaction is studied in a behavioral experiment, measuring the timbral adjustments performers employ. Several timbre descriptors serve as acoustic measures, quantifying global and formant-based spectral-envelope properties. Furthermore, musicians’ self-assessment of their performances is measured through behavioral ratings. The performances are investigated across four factors, i.e., room acoustics, communication directivity, musical voicing, and leading vs. accompanying roles. Findings from ANOVAs suggest that differences in role assignments and communication directivity between performers lead to timbral adjustments. These effects are more pronounced for horn than for bassoon and performer interdependencies appear to be most important for unison voicing.
Predicting blend between orchestral timbres using generalized spectral-envelope descriptions
Predicting blend between orchestral timbres using generalized spectral-envelope descriptions Lembke, Sven-Amin; Narmour, Eugene; McAdams, Stephen Composers rely on implicit knowledge of instrument timbres to achieve certain effects in orchestration. In the context of perceptual blending between orchestral timbres, holistic acoustical descriptions of instrument-specific traits can assist in the selection of suitable instrument combinations. The chosen mode of description utilizes spectral-envelope estimates that are acquired as pitch-invariant descriptions of instruments at different dynamic markings. Prominent local spectral-envelope traits, such as spectral maxima or formants, have been shown to influence timbre blending, involving frequency relationships between local spectral features, their prominence as formants, and constraints imposed by the human auditory system. We present computational approaches to predict timbre blend that are based on these factors and explain around 85% of the variance in behavioral timbre-blend data. Multiple linear regression is employed in modeling a range of behavioral data acquired in different experimental investigations. These include parametric investigations of formant frequency and magnitude relationships as well as arbitrary combinations of recorded instrument audio samples in dyads or triads. The cataloguing of generalized acoustical descriptions of instruments and associated timbre-blend predictions for various instrument combinations could serve as a valuable aid to orchestration practice in the future.
A spectral-envelope synthesis model to study perceptual blend between wind instruments
A spectral-envelope synthesis model to study perceptual blend between wind instruments Lembke, Sven-Amin; McAdams, Stephen Wind instrument sounds can be shown to be characterized by pitch-invariant spectral maxima or formants. An acoustical signal-analysis approach is pursued to obtain spectral-envelope descriptions that reveal these pitch- invariant spectral traits. Spectral envelopes are estimated empirically by applying a curve-fitting procedure to a composite distribution of partial-tone frequencies and amplitudes obtained across an instrument’s pitch range. A source-filter synthesis model is designed based on two independent formant filters with their frequency responses matched to the spectral envelope estimates. This is then used in perceptual experiments in which parameter variations of the synthesis filter are manipulated systematically to investigate their contribution to the degree of per- ceived blend between the synthesized sound and a recorded instrument sound. The perceptual relevance is assessed through two tasks in which participants either produce the best attainable blend by directly controlling synthesis parameters or rate the degree of blend for 5 parameter presets. Behavioral data from both experiments suggest the utility of this formant-based model for correlating pitch-invariant acoustical description with perceptual relevance, as both formant frequency and magnitude appear to affect perceived blend.
Timbre blending of wind instruments: acoustics and perception
Timbre blending of wind instruments: acoustics and perception Lembke, Sven-Amin; McAdams, Stephen The acoustical and perceptual factors involved in timbre blending between orchestral wind instruments are investi- gated based on a pitch-invariant acoustical description of wind instruments. This description involves the estimation of spectral envelopes and identification of prominent spectral maxima or ‘formants’. A possible perceptual relevance for these formants is tested in two experiments employing differ- ent behavioral tasks. Relative frequency location and mag- nitude differences between formants can be shown to bear a pitch-invariant perceptual relevance to blend for several in- struments, with these findings contributing to a perceptual theory of orchestration.

Click here to view Sven-Amin Lembke's full listing of publicaitons and outputs

Research interests/expertise

Audio / music technology
Room / music / psychological acoustics
Musicology

Areas of teaching

Acoustics (eg room acoustics, musical acoustics, psychoacoustics, electroacoustics) Perception and cognition of music and sound
Computational analysis and modelling of music

Qualifications

PhD in Music Technology (2015), McGill University, Montreal, Canada
MA in Musicology, Acoustics, Audio Technology (2007),Technische Universität, Berlin, Germany

Courses taught

MUST1001: Foundations of Music
MUST2004: Creative Coding for Music
MUST2005: Sound and Image
TECH1020: Introduction to Audio Production
TECH3010: Technology Project (supervision)
TECH3011: Studio Technology

Membership of professional associations and societies

European Society for the Cognitive Sciences of Music (ESCOM), 2015 - present
Audio Engineering Society (AES), 2015 - present

Conference attendance

July 2016: Lembke S-A, An exploration of psychoacoustic factors influencing the perception of triangular sound shapes. Poster presented at 14th International Conference on Music Perception and Cognition (ICMPC- SMPC), San Francisco, USA

October 2015: Lembke S-A, Levine S, de Francisco M and McAdams S, The use of microphone level balance in blending the timbre of horn and bassoon players. Paper presented at Audio Engineering Society Convention 139, New York City, USA

December 2014: Lembke S-A and McAdams S, Timbre’s role in music: investigating its dependency on pitch and dynamics during musical performance. Paper presented at 9th Conference on Interdisciplinary Musicology (CIM), Berlin, Germany

August 2014: Lembke S-A, Levine S, de Francisco M and McAdams S, The influence of performer roles on timbre blending between bassoon and horn players. Paper presented at 13th International Conference on Music Perception and Cognition (ICMPC-APSCOM), Seoul, South Korea

August 2013: Lembke S-A, Levine S, de Francisco M and McAdams S, Measuring the interaction between bassoon and horn in achieving timbre blend. Paper presented at Stockholm Music Acoustics Conference (SMAC) and Sound and Music Computing (SMC) Conference, Stockholm, Sweden

June 2013: Lembke S-A, Narmour E and McAdams S, Predicting blend between orchestral timbres using generalized spectral-envelope descriptions. Paper presented at International Congress on Acoustics, Montreal, Canada

May 2013: Lembke S-A, Levine S, de Francisco M and McAdams S, Timbre blending as a performance variable: investigation of the interactive relationship between performers and a sound-recording engineer. Paper presented at Centre for Interdisciplinary Research in Music Media and Technology (CIRMMT) Student Symposium, Montreal, Canada

August 2012: Lembke S-A and McAdams S, Establishing a spectral theory for perceptual timbre blending based on spectral-envelope characteristics. Poster presented at 12th International Conference on Music Perception and Cognition (ICMPC-ESCOM), Thessaloniki, Greece

April 2012: Lembke S-A and McAdams S, A spectral-envelope synthesis model to study perceptual blend between wind instruments. Paper presented at 11th Congrès Français d’Acoustique and IOA annual meeting (Acoustics 2012), Nantes, France

August 2011: Lembke S-A and McAdams S, The relevance of spectral shape to perceptual blend between wind instrument timbres. Paper presented at Society for Music Perception and Cognition (SMPC), Rochester, NY, USA