xtl /Vo0 , 6 Z se PERCEPTION OF TIMBRAL DIFFERENCES AMONG BASS TUBAS THESIS Presented to the Graduate Council of the North Texas State University in Partial Fulfillment of the Requirements For the Degree of MASTER OF MUSIC By Gary Thomas Cattley, B.A. Denton, Texas August, 1987 Cattley, Gary T., Perception of Timbral Differences among Bass Tubas. Master of Music (Music Education), August, 1987, 98 pp., 4 tables, 6 figures, bibliography, 74 titles. The present study explored whether musicians could (1) differentiate among the timbres of bass tubas of a single design, but constructed of different materials, (2) determine differences within certain ranges and articulations, and (3) possess different perceptual abilities depending on previous experience in low brass performance. Findings indicated that (1) tubas made to the same specifications and constructed of the same material differed as much as those of made to the same specifications, constructed of different materials; 2) significant differences in perceptibility which occurred among tubas were inconsistent across ranges and articulations, and differed due to phrase type and the specific tuba on which the phrase was played; 3) low brass players did not differ from other auditors in their perception of timbral differences. TABLE OF CONTENTS Page LIST OF TABLES . - . - . v LIST OF ILLUSTRATIONS . .*. ... .vi Chapter I. INTRODUCTION ............. Purpose of the Study Research Questions Definition Delimitations Chapter Bibliography II. REVIEW OF THE RELATED LITERATURE . 14 The Perception of Timbre Background Acoustical Attributes of Timbre Subjective Aspects of Timbre Subjective Measurement of Timbre Contextual Presentation of Stimuli The Influence of Materials on Timbre Chapter Bibliography III. METHODS AND PROCEDURES . 41 The Pilot Studies The Present Study The Selection of Stimuli The Test Tape Subjects Statistical Procedures Chapter Bibliography IV. TREATMENT OF THE DATA.. .... .. 50 Reliability Main Effects and Interactions iii TABLE OF CONTENTS Continued V. CONCLUSIONS. .. .. 66 The Research Questions Research question #1 Research question #2 Research question #3 Research question #4 Discussion Suggestions for Further Research Chapter Bibliography APPENDIX - - - - . * - * . *.. ... 80 Raw Data Test Form BIBLIOGRAPHY . o - . - . 86 iv LIST OF TABLES Table Page I. Main Study Analysis of Variance Source Table . --- 53 II. Homogeneous Subsets, Phrase Main Effects . 55 III. Homogeneous Subsets, Pair Main Effects . 56 IV. Homogeneous Subsets, Pair by Phrase Interaction . 59 V LIST OF ILLUSTRATIONS Figure Page I. Musical Examples . 0 . 0 44 II. Scheffe Procedure, Phrase Main Effect . 54 III. Scheffe Procedure, Pair Main Effect . 55 IV. Scheffe Procedure, Pair by Phrase Interaction . 57 V. Scheffe Procedure, Rater by Phrase Interaction . 64 VI. Group Means Rater by Phrase Interaction . 65 vi CHAPTER I INTRODUCTION The materials used in construction of a musical instrument and the resultant effects on that instrument's tone quality have long been an issue of curiosity and debate. Backus suggested that the first such discussion may well have involved cavemen's preferences for the sound of a flute made of bone rather than of wood (2, p. 247). The use of various compositions of brass in the manufacture of brass instruments has evoked similar discussion and debate among contemporary manufacturers and as well as performers. There have been a wide variety of claims regarding the extent to which different materials and finishes have an effect on tone quality. Construction materials are only one of the many differences between instruments, yet certain materials significantly influence the cost' of the instrument. If the more expensive materials do not alter noticeably the timbre of the instrument, one would then have to consider whether the. resulting appearance of the tuba is worth the added costs. 1 2 Many opinions have been offered concerning the significance or insignificance of material and wall thickness in respect to their effects on the timbre of brass instruments. Some are based on scientific research; others rely on players' or instrument makers' practical experience. Bevan, while not citing specific responses, acknowledged that players' reactions differ from tubas with heavier or lighter gauge walls, but maintained there is no scientific basis for this (9, pp. 45-46). Smith wrote, "Great claims have been made for the acoustical properties of various alloys, especially the expensive ones." He also indicated that the effect of metallic composition of a trumpet bell is only significant with thinner gauges of metal (26, pp.28-29). In an interview, Reynold Schilke of Schilke Music Products stated "The material. (of brass instruments] . is relatively unimportant; it's what you do with it that makes the difference!" (27, p.50); however, in the same article his father, who founded the company, was reported to have said that the application of lacquer ". killed an instrument" (27, pp.50-51). In an effort to systematically settle this controversy, researchers have explored the relationship of timbre and construction material on many instruments; yet, the tuba has not been considered specifically. However, considerations for other 3 instruments can be generalized to apply to instruments of different families, and as such, provide the background for the present study (2, pp. 247, 252, 279). Backus noted that ". the material of the wind instrument may be chosen for its working qualities and not for any imagined effect on its tone" (2, p. 247). Many studies support this statement, and many opinions exist to the contrary. Analyses of tones of wooden and metal clarinets and flutes showed ". no appreciable effect" on tone quality due to the composition or thickness of wall materials (21, p. 417; 12, pp. 520-523). Concerning the flute and oboe, Bate reflected that many players' ideas, contrary to scientific opinion, allowed for differences in tone quality attributable to construction materials (6, p. 160; 7, p. 24). Baines, Rendall, and Miller suggested marked differences in the playing characteristics and timbre of woodwinds due to superior and inferior materials (5, pp. 54-56; 24, pp. 12-13; 19, pp. .161-171). Backus related an experiment which compared and found no difference among the tones of brass and wooden trumpets (2, p. 279). Knauss and Yeager found that the amount of vibration occurring in the walls of a trumpet did not possess enough acoustical energy to be heard above the actual sound produced by the 4 instrument (18, pp. 160-162). By means of computer models, Watkinson and Bowsher studied the vibration characteristics of trombone bells of various shapes and materials. While modes of wall vibrations for different materials differed slightly, the significance of the observed properties was not determined with respect to the perception (33, pp. 1-16). Despite the general scientific evidence which excluded contribution of material to tone quality, a plethora of contrary opinions exist. One of the first articles addressing the proper composition of metals for constructing a brass instrument appeared in the Talbot manuscript of the Christ Church: "Best mettal Bastard-Brass mixed with solid Brass: Worse Silver and worst copper springy." (4, p. 20). While the meaning of this entry is far from precise, it does indicate a preference for the use of particular alloys in the manufacture of brass instruments. Ferron felt that the walls of the tubing of brass instruments vibrate sympathetically with the air column, both radially and longitudinally, and that the material of which the instrument is made influenced its sound due to these vibrations. In addition, he related that a musician actually imprints his personal sound upon his instrument through unique formant frequencies, thereby increasing the flexibility of the instrument 5 and, thus, enhancing its response to that player's individual signature (14, p. 57). This view also appears in other anecdotal literature (23, pp. 29-31; 28, pp. 18-19). Poncet stated that since vibrations are reflected off the walls of an instrument, the sound quality largely relates to the composition of the metal. Additionally, he offered that in the hands of a bad player, a horn may lose flexibility and mellowness in the same manner as it may be improved by a good player (23, pp. 29-31). Tuckwell cited pronounced differences in timbres of French horns constructed of different compositions of metals (30, p. 149). Morley-Pegge related the opinions of two noted hornists who expressed preference for certain alloys on grounds of tone quality (20, pp. 125-126). Baines allowed for some contributions of wall vibrations to inharmonic overtones in brass instruments (3, p. 24). Benade also reasoned that material could effect the timbre of an instrument, but for different reasons than those previously suggested. Plastics used in the manufacture of woodwinds allowed sharper edges around the tone holes and joints than wood. These edges purportedly caused turbulences which disrupted the air column inside the instrument and changed its tone quality (8, pp. 499-501). 6 Brass instrument manufacturers' claims for certain characteristic sounds due to material are both inconsistent and contradictory. Complications in associating timbral characteristics of instruments with certain mixtures of metal and assorted finishes arise when one considers the number of other factors that can cloud the issue. For example, instruments of various tubing configurations inherently are different; individual players can produce a broad spectrum of sounds, even on the same instrument; and a listener may consider an instrument's qualities to be different from a player's perception of the same because of the performer's proximity to the source of sound (16, pp. 15-17; 33, p. 1193; 10, pp. 23-24). The description of perceived differences also is problematic. Many inexact terms, viz., bright, dark, core, focused, spread, compact, are used in the description of perceived musical sounds. Although there seems to be some agreement as to the application of such terms among musicians, great latitude in the particular attributes that fit these terms is also commonplace (1, pp. 1-7; 16, p.