Sound Quality of Flue Organ Pipe. An Interdisciplinary Study on the Art of Voicing

Doctoral thesis, 2001

This thesis presents a research study carried out in collaboration with a department of applied acoustics, a department of musical acoustics and an organ workshop. The description of the sound quality of flue organ pipes has received fairly little attention either in organ-building or scientific literature, despite its importance in the overall quality of the instrument, probably due to the difficulties inherent in doing so. This thesis addresses this issue while focusing on the process of voicing a flue organ pipe. The treatment of such a topic requires an interdisciplinary approach in the use of methods and results that have originated in acoustics, signal processing, experimental psychology and linguistics. The voicing process performed on a flue organ pipe can change several characteristics of the pipe sound. A review of practical and theoretical works shows that there is no well-established way of describing this voicing process, despite the fact that one can recognize different styles of voicings generally emerging from the aesthetics of a particular historical period or from the remarkable creativity of an individual organ-builder. Gathering information from a particular research organ workshop engaged principally in the reconstruction of baroque organs, an attempt is thus made to compare the descriptions obtained from an expert voicer with physical analyses made on experimental pipes or psychological analyses made on a pool of test participants. Papers I and IV address specific methodological problems related to the administration and type of listening tests which were used in this work. The methodology presented in Paper I makes active use of computers for the administration, storage and analysis of listening tests. A specific programming environment was built for this purpose. Paper IV focuses specifically on a test module which combines the advantages of classical methods such as free verbalization, categorization, multiple comparison and semantic differentials. Papers II and III show that it is possible to produce a structured list of verbal descriptors suitable for the description of flue organ pipe sounds through a combination of qualitative and quantitative analyses of test participants' responses. Three main steps were involved. First, an original list was constructed from the description of an expert voicer. This list was then extended by means of a qualitative analysis of test subjects' verbal comments. Finally, a factor analysis of a semantic differential test provided a structured normative lexicon.