Kit Soden’s research while affiliated with McGill University and other places

This article presents a framework for classifying instrumental timbres, addressing the expanding sonic possibilities in contemporary orchestration and musical practice. As composers move beyond pitch-centered traditions, integrating noise-based effects and extended techniques—new analytical tools become necessary. This study introduces the concepts of metatimbre and paratimbre, structuring and applying them through Metatimbre Classes (MetCs) to categorize timbres based on perceptual similarity rather than instrumental origin or technique. MetCs encompass single-instrument, multi-instrument, or hybrid sources, grouping timbres under musical archetypes such as “flute-like” or “breath-like.” Analyses of György Ligeti’s Kammerkonzert and Helmut Lachenmann’s temA illustrate the framework’s applicability. By shifting the focus from individual instruments and their techniques to broader timbral groupings, this framework provides a structured approach for analyzing and conceptualizing timbre and its functional role in orchestration.

Timbral blend is a phenomenon that occurs when two or more concurrent acoustic events produced by distinct sources fuse perceptually and give rise to new timbres. Auditory scene analysis proposes that concurrent grouping cues of onset synchrony, harmonicity, and parallel change in pitch and dynamics are involved in the perceptual fusion of events, but research has also shown that several timbral cues can affect concurrent grouping. We investigated potential factors that may cause different degrees of instrumental blend in orchestral excerpts using rating scales ranging from “unity” to “multiplicity” and from “strongly blended” to “not at all blended.” With linear mixed effects modeling, the factors found to affect ratings included the rating scale used, musical training, timbre class (instrument families involved), the degree of parallelism and onset synchrony of melodic lines involved in the blend, the number of different notes present simultaneously, and several acoustic features related to timbre. Musicians differ from nonmusicians in the use of the multiplicity scale, rating excerpts as more multiple, even if they are fairly well blended, whereas nonmusicians ratings are similar for both scales and to musicians’ ratings of blend. Excerpts with bowed strings and/or woodwinds blend the strongest, followed by combinations involving brass instruments, with excerpts involving percussion and plucked strings blending the least. The important finding of this study on real musical excerpts is in demonstrating the relative roles of the score-based and acoustic factors that are associated with the perception of multiplicity and blend in complex orchestral sonorities as well as the influence of musical training.

Timbre perception and auditory grouping principles can provide a theoretical basis for aspects of orchestration. In Experiment 1, 36 excerpts contained two streams and 12 contained one stream as determined by music analysts. Streams—the perceptual connecting of successive events—comprised either single instruments or blended combinations of instruments from the same or different families. Musicians and nonmusicians rated the degree of segregation perceived in the excerpts. Heterogeneous instrument combinations between streams yielded greater segregation than did homogeneous ones. Experiment 2 presented the individual streams from each two-stream excerpt. Blend ratings on isolated individual streams from the two-stream excerpts did not predict global segregation between streams. In Experiment 3, Experiment 1 excerpts were reorchestrated with only string instruments to determine the relative contribution of timbre to segregation beyond other musical cues. Decreasing timbral differences reduced segregation ratings. Acoustic and score-based descriptors were extracted from the recordings and scores, respectively, to statistically quantify the factors involved in these effects. Instrument family, part crossing, consonance, spectral factors related to timbre, and onset synchrony all played a role, providing evidence of how timbral differences enhance segregation in orchestral music.