Perception and verbalisation of voice quality in western lyrical singing: Contribution of a multidisciplinary research group

Actes disponibles en ligne : http://www.uni-graz.at/~parncutt/cim07/index2.htmInternational audienceBackground in music performance. In the field of lyrical singing, an extensive terminology is dedicated to voice quality description. Among the many terms, some are used with consistent meaning by virtually all voice specialists, whereas others, which are more metaphorical or aesthetic, have multiple meanings despite frequent use. The descriptors used by voice specialists deal not only with the perceived sound, but also with its production. Imitation is often used as a complement to verbal description. In parallel, physicians and speech therapists have developed a vocabulary in their practice to describe voice quality in the case of pathological voices. Their listening is primarily oriented to the search of « defects » for diagnosis. Much effort has been expended in the field to retain the most consensual and appropriate terms for perceptual discrimination of different vocal pathologies. Background in acoustics. Acousticians do not have a specific vocabulary for voice description. They often make use of terms related to timbre. Many studies conducted on the determination of physical criteria for voice-quality description imply a listening focused on voice spectral content and transient phenomena. Because of source-filter theory, acousticians make a distinction between voice-quality aspects related to vocal-fold vibratory movements and those related to vocal-tract configurations. Aims. Perception of voice quality is not objective, as it depends on the listener's own experiences and expectations. However, a consensus may be found on its verbal description, in a similar way to the technical vocabulary in winetasting. Our aim is to elaborate a common terminology for voice-quality description in voice pedagogy, voice therapy and musical acoustics. This paper presents a three-year study conducted by a research group composed of musical acousticians, speech therapists, singers, singing teachers and choir directors, in an attempt to characterise the notion of voice quality and to describe perceived voice quality in the case of lyrical voices with the help of a listening grid based on consensual terms and illustrative sound examples. Main contribution. Voice quality is a term with multiple meanings related to acoustical aspects (intensity, pitch, spectral content, etc) and aesthetic or subjective aspects. Its definition also depends strongly on the context. When trying to elaborate a common language to describe the perception of voice quality, several fundamental aspects of perception of a sensory process must be considered. These aspects have a direct consequence on its verbal description. Perception tends first to identify an object, so as to compare it to pre-established mental categories. Analytical perception may occur thereafter and the verbal descriptors then depend on the object's initial categorisation. Therefore, the idea of a listening-oriented grid was suggested. It allows the listener to concentrate on a given aspect of voice quality. Such a grid has been established on three main axes: Perception of vocal gesture or vocal technique, perception of sound, and perception of performance. The first axis is mainly presented here. Perception is also differential: An object is always evaluated or described by comparison to a reference in memory. The descriptive terms are defined, and illustrated with reference sound examples. Implications. The proposed listening-oriented grid facilitates the perceptual and verbal description of voice quality in singing. It may be used as a tool for vocal pedagogy. It will also provide voice professionals with a consensual terminology for expressing singing voice-quality perception