William K. Koehler, Illinois State University

Applied string teaching methodologies are largely derived from pedagogical practices of the Baroque, Classical, and Romantic periods. The dominant mode of applied string teaching has been a modeling approach, while anatomical aspects of string playing have received little systematic attention. Achievement in bowing technique, in particular, has been accomplished primarily through modeling and not through analysis of the relationships among the various muscles involved in executing bowings.

Little is known about physiological and biomechanical aspects of the interaction of muscles in performance of various bowing types. Further, little is known about the extent to which feedback concerning muscle tension might affect performance quality. Observation and analysis of bowing technique employing mechanized measurement approaches could provide more objective and reliable data. With modem electronic equipment, researchers are able to obtain ratio-level physiological data related to string playing. Through such monitoring of muscle tension, performance of rhythmic accuracy, articulation, tone quality, tempo consistency, and intonation could directly be improved. With the exception of vibrato, all manners of expression on a stringed instrument are accomplished with the bow arm. It follows that knowledge of the relationships among muscle groups involved in the performance of the various bowing types is of great interest to string performers and teachers. One way to illuminate this issue is feedback by means of electromyography.

Since its origin in the early 1950s, biofeedback has received much attention from both biomechanics researchers and cognitive psychologists. Biofeedback is a method for providing contiguous external information in the form of auditory signal or visual display about internal physiological activity. Auditory feedback can be presented by providing intermittent auditory signals that sound when a threshold is exceeded, or by providing a constant tone which varies in pitch according to the level of muscle expenditure. In this clinical application, the subject is prompted to reduce or increase activity in a targeted muscle group. Clinical applications of EMG biofeedback provide continuous external information to the subject. Further, biofeedback can be accompanied by training. In this application, which is referred to as self-regulation, the subject is taught how to achieve a desired result by modification of behavior on the basis of continuous feedback. The analogy can be drawn between biofeedback and computer assisted instruction in that both offer immediate feedback to enhance learning. In much the same way a student works with a strobotuner to correct intonation problems, a student can work with a myograph to minimize excess tension levels on specific muscle groups. Since it is widely accepted that unnecessary muscle tension inhibits performance quality, and may lead to fatigue or even physical injury, it follows, that the efficient use of muscles is of great importance to performers and teachers.

The main objective of this study was to determine the effect of electromyographic biofeedback training on achievement in spiccato and sautille bowing technique. Forty-seven subjects (24 experimental, 23 control) participated in four 75-minute sessions. The experimental group received aural feedback, visual feedback, and traditional instruction; while the control group received traditional instruction. EMG biofeedback training was used in the experimental group to reduce muscle tension in targeted muscle groups of the bow arm. On the spiccato bowing, subjects were instructed to reduce forearm flexor EMG; while, on the sautille`bowing, the trapezius muscle group was targeted for EMG reduction. The control group received traditional instruction with no aural or visual feedback. During each treatment session, 16 performance measures were taken.

A Grass four-channel myograph, analog to digital converter, computer, threshold beeper, sound pressure meter, electrodes, tape recorder and recording tape were used in data collection. Electrodes were placed on the trapezius, posterior deltoid, bicep, and the forearm flexor muscle groups of the right arm. Data were then integrated and rectified, yielding macro data in millivolt/seconds units. Achievement scores for the spiccato and sautille` bowing types were determined from the evaluations of three judges using a pretest/posttest design. Descriptive data on muscle tension between performance measures, and pre and post test assessments were collected. Relations among performance data, instrument, and experience level were examined. This study also employed single subject designs to monitor subjects' performance across experimental treatment sessions. Data were analyzed using MANOVA and correlation statistical procedures.

The results of the Repeated Measures MANOVA procedures indicated that the experimental group scored significantly higher on all performance measures of Rhythmic Accuracy, Articulation, Tone Quality, Tempo Consistency, Intonation, and Composite Performance (see Tables 1 and 2). In examining the group by pre/post interaction, low strings in the experimental group scored significantly higher on Rhythmic Accuracy, Articulation, Tone Quality, Tempo Consistency, and Composite Performance. Both experimental and control groups improved significantly from pretest to posttest on all performance measures.

tercorrelations among muscle groups for spiccato bowings on pretest and posttest muscle expenditure data revealed that, following treatment, the degree of forearm flexor expenditure tended to be independent of the other muscle groups on spiccato (See Table 3). For sautille, significant correlations between the forearm flexor and bicep were found in both groups on the posttest (see Table 4). On pretest and posttest assessments, strong correlations were found on all performance measures with the exception of rhythmic accuracy. Posttest correlations between muscle expenditure and performance variables in the experimental group revealed that all performance measures with the exception of intonation were correlated with Posterior Deltoid. In the control group, all correlations of performance measures with muscle expenditure were non-significant. On posttest correlations of muscle expenditure and performance variables for sautille, all correlations of performance measures with muscle expenditure were non-significant.

String teachers have been successful in developing methodologies which foster virtuostic performance technique as result of increased emphasis on how various aspects of performance (bowing, shifting, vibrato, finger motion, etc.) are executed. Muscles work in pairs. In normal joint movement, one muscle flexes while the other loosens. However, when both muscles of a particular muscle group flex at the same time, movement in the joint becomes "frozen" or inhibited. Thus, when excess tension in a joint exists, bowing technique is adversely affected since an overworked muscle will quickly become fatigued. As was found in this study, the performance measures of rhythmic accuracy, articulation, tone quality, tempo consistency ,and intonation were adversely affected by excess tension in a muscle group.

Teachers, researchers, and performers who become familiar with electromyography can benefit from this technology by gaining increased knowledge of the interactions among muscles in the bow arm. Biofeedback equipment can often be found at universities, health service centers, or student counseling centers. For self-monitoring purposes, only minimal training in the use of biofeedback equipment is necessary.

The benefits of biofeedback training in this study were many-fold. The majority of subjects in this study reported that they gained a kinesthetic awareness while responding to the biofeedback, and came away from the study with an increased ability to "tune in" to body motions, relax specific muscles, and improve their bowing technique. It follows, that the use of electromyography may provide important pedagogical insights which enhance applied teaching capabilities and performance skill acquisition.

Subjects receiving biofeedback training performed significantly better in the areas of rhythmic accuracy, articulation, tone quality, tempo consistency, intonation, and a composite measure of performance. Further, bassists and cellists receiving biofeedback training performed significantly better in these areas than did violinists and violists receiving biofeedback training or both high or low string players who received only the traditional instruction. This finding indicates that low strings benefited most from biofeedback training. This result was expected since cellist and bassists characteristically expend more energy due to the physical demands of their instruments. For cellists and bassists, muscle expenditure on the trapezius and posterior deltoid was found to be significantly higher than that of violin and viola. It follows that for cellists and bassists, efficiency and endurance are important factors which promote advanced performance technique.

In examining relationships among muscle groups of the bow arm, it was found that following treatment, forearm flexor expenditure tended to be independent of the other muscle groups on spiccato. This desirable trend was reflected in both the experimental and control groups, but the trend was stronger for those subjects receiving biofeedback treatment. In executing the spiccato stroke, the trapezius muscle should account for the most muscle expenditure. The trapezius bears the weight of the whole arm, and the other muscle groups function independently. The posterior deltoid should also act independently from the trapezius. Following treatment, no relationship between forearm flexor and trapezius of the bow arm, was found. These findings support the independent nature of muscle expenditure among muscle groups in the performance of spiccato.

On sautillé excerpts, significant correlations between the forearm flexor and bicep were found in both groups following treatment sessions. Again, this trend was stronger in those subjects receiving biofeedback instruction. In executing the sautille` stroke, more distribution of expenditure among muscle groups is necessary. When movement in the forearm flexor and posterior deltoid is inhibited, excess tension results. This in turn, produces a fixed bow arm which contributes to excess trapezius expenditure. Further, the relationship between the forearm flexor and bicep is an important one. The bicep must move the elbow in order to contribute to the "shaking motion" necessary to execute the sautillé correctly.

In summary, a primary goal of string teachers is to provide the most efficient instruction which in turn develops a sound and dependable technique in their students. In this study, both the subjects receiving biofeedback training and those receiving only traditional instruction improved significantly following treatment on all measures of performance. However, string players receiving biofeedback training reduced posterior deltoid expenditure while posterior deltoid expenditure in those receiving only traditional instruction increased. Therefore, biofeedback training was found to be a valuable addition to traditional instruction.

In closing, Mantel (1972) posed two questions about the process of learning to play a stringed instrument: (a) What must be learned?, and (b) How should it be learned? The former concerns the detailed motor processing of all movements involved in performing on a stringed instrument. The latter addresses the most efficient and practical ways of learning these detailed motor patterns. Janos Starker, the legendary performer and teacher of cello at Indiana University, recently asked the following question in his masterclass at Illinois State University: "Why should we adopt such a scientific approach to learning a stringed instrument?" His answer was "to save time." A scientific, or data-based approach to string playing, offers the potential for increased efficiency in teaching methodologies. Such efficiency in teaching can help to coordinate muscular expenditure and movement. Scientific, or data-based approaches clearly can play a role in the development of stylistic and interpretive judgments necessary for artistic expression.