1. Current Developments in Timbre Research Kai Siedenburg, Charalampos Saitis, Stephen McAdams



The goal of this chapter is to provide a roadmap and context for the whole volume. Hence, the chapter will provide a conceptual introduction to the notion of timbre and a brief survey of important steps in the history of timbre research. The content of the subsequent chapters will be briefly outlined and situated in an interdisciplinary framework, followed by a discussion of important research questions on timbre.





PART I: PRINCIPAL PERCEPTUAL PROCESSES







2. The Perceptual Representation of Timbre



Stephen McAdams



This chapter covers the current state of knowledge about the structure of timbre's perceptual representation. It discusses dimensional models of timbre based on multidimensional scaling (MDS) of timbre dissimilarity ratings and addresses various extensions of MDS models as well as psychophysical explanations in terms of acoustical correlates of perceptual dimensions. It further covers research on the covariance of timbre, pitch, and loudness and discusses the ways in which this covariance affects the recognition and identification of sound sources. It further outlines the utility of considering high-dimensional acoustic representations such as modulation spectra as an acoustic basis for timbre modeling.







3. Timbre Categorization and Recognition



Trevor Agus, Clara Suied, Daniel Pressnitzer



There have been many important and intriguing empirical findings on the categorization and recognition of sounds in the last seven years. This chapter reviews these studies and specifically examines the minimal amount of acoustic and temporal information required to recognize sounds such as repeated noise bursts, isolated instrument sounds, or polyphonic musical textures. The chapter thus addresses the core question regarding the timbre cues utilized by humans for the recognition of various classes of sounds.







4. Memory for Timbre



Kai Siedenburg, Daniel Mullensiefen



This chapter discusses research on long- and short-term memory for timbre. A guiding question is whether timbre is stored independently from other mental tokens (e.g., pitch as in musical melodies, or words as in verbal utterances), and whether it is governed by the same principles as those observed in these neighboring domains. Finding answers to these question will involve decomposing memory for timbre into cognitive processes such as perceptual similarity, chunking, semantic encoding, as well as accounting for the factor of auditory expertise.







5. Concepts and Semantics in Timbre Perception



Charalampos Saitis, Stefan Weinzierl



In this chapter, verbal descriptions of timbre and the rich semantic associations found in them are considered. Metaphorical linguistic structures are central to the process of conceptualizing timbre by allowing the communication of subtle acoustic variations in terms of other more commonly shared sensory experiences--for instance, a sound felt, seen, or tasted as "velvety." A critical question addressed is the relationship between the semantics underlying the linguistic description of timbre and its perceptual dimensions.







6. Neural Basis of Timbre Processing



Bruno Giordano



This chapter reviews recent findings regarding the neural basis of timbre information processing from studies using both animal models as well as human brain imaging. This includes the specific neural correlates of spectral and temporal shape discrimination, findings regarding the cortical representation of spectrotemporal information, and more general models of sound source identity processing in cortex.







PART II: SPECIFIC SCENARIOS



7. Voice Processing and Voice Identity Recognition



Samuel Mathias, Katharina von Kriegstein



Humans effortlessly extract a wealth of information from speech sounds, including semantic, emotional, and details related to speaker identity. The chapter reviews the basic principles of human vocal production, behavioral studies on the processing and recognition of familiar and unfamiliar voices, as well as neural mechanisms and models of speaker recognition. The chapter further introduces to phonagnosia, the deficit of not being able to recognize familiar people by their voices and discusses its relation to autism spectrum disorder.







8. Timbre as a Structuring Force in Music



Stephen McAdams



Timbre plays a substantial part in shaping the perceptual experience of music. This chapter reviews the processes that may serve as the basis of this phenomenon with a particular focus on auditory scene analysis principles. Specific perceptual processes to be addressed include timbre's dependence on concurrent grouping (including timbral blend), the processing of sequential timbral relations, its role in sequential and segmental grouping, and the contribution of these grouping processes to musical structuring. The discussion draws from psychophysical studies as well as a discussion of selected musical examples from the Western orchestral repertoire.







9. Timbre Perception with Cochlear Implants



Jeremy Marozeau



The chapter outlines timbre perception of patients with severe or profound hearing loss that have received a cochlear implant (CI). Whereas the perception of speech in quiet works relatively well for CI patients, music perception or voice identity perception still pose great problems. The chapter will discuss CI research on timbre dissimilarity perception, musical instrument identification, auditory stream segregation, issues in voice identity and gender recognition, as well as potential improvements for CI coding strategies.







10. Timbre, Sound Quality, and Sound Design



Guillaume Lemaitre, Patrick Susini



This chapter focusses on the role of timbre in the evaluation of product sounds, related to the question of how sounds contribute to the aesthetic, functional, and emotional aspect of a product.



Research in this domain has utilized multidimensional scaling in conjunction with acoustic-descriptor-based approaches and regression modeling in order to develop models of sound quality that can be applicable in sound design. Example cases are diverse and include products such as car horns, wind turbines or consumer electronics devices such as printers. Implications for approaches to sonic interaction design are discussed.







PART III: ACOUSTICAL MODELING