Abstract
This study uses real-time (cine) MRI to examine how orofacial myofunctional disorders (OMDs) affect muscle function during speech and horn playing. Dynamic MRI images were captured of an OMD subject and control subjects reciting a speech task and sustaining a note on an MRI- compatible horn. A following visual feedback session allowed the OMD subject to view and react to their (cine) MRI next to the image of an elite subject. Profile lines created in MATLAB allowed analysis of muscle function and changes in oral cavitation between the OMD and control subjects. In both the speech and horn films, the OMD subject consistently utilized maladaptive muscle movements, resulting in low and forward tongue position against the front teeth. Both control subjects had tongue placement free of the front teeth, and the horn control subject could elevate the tongue to narrow the air stream and play higher pitches. The MRI films suggest a connection between speech disorders and compromised horn-playing technique. OMDs limit the ability of the tongue to make the changes in oral cavitation used to play different pitches on the horn.
INTRODUCTION
Orofacial myofunctional disorders (OMDs) include incorrect muscle functions of the tongue, lips, jaw, and face. Of these habits, “tongue thrust,” is the most common disorder (Hanson & Mason, 2003, p. 3). The tongue sits low and forward in the mouth when at rest and pushes against the front teeth when swallowing. This often results in an open- mouth rest position and breathing posture as well as misarticulated speech. The most common speech errors include /t, d, l, n, r, sh, ch, dz, s, and z/. Other negative effects include weak lateral borders of the tongue, reliance on the jaw to move the tongue, and tension in the lips when swallowing (Hanson & Mason, 2003, p. 5).
Playing a brass instrument requires precise coordination and motor control of the tongue, lips, and jaw. Playing different pitches involves manipulating the size and space of the oral cavity as the tongue directs the airstream to create faster or slower moving air. To play in the high register, the tongue arches and creates a narrow, centralized channel for faster moving air. To play in the lower register, the tongue lowers to create a bigger oral space and slower moving air. Iltis et. al describes these oral cavitation changes in detail in his RT-MRI analysis of elite horn players (Iltis, et al., 2016, p. 6).
Directing the airstream into the mouthpiece requires a focused embouchure, or the formation of the lips and surrounding muscles to form a vibrating “buzz.” The orbicularis oris, as well as surrounding cheek and jaw muscles, regulate the tension of the lips. The faster the airstream, and the faster vibration of the buzz, the higher the pitch becomes. The tongue is also used for articulation, to initiate notes. As the player blows air into the instrument, a precise note front is created with the tip of the tongue. In his manual on horn playing, Farkas describes this motion as a “pulling away of the tongue which allows the air to flow between the lips.” He indicates that the tongue should make contact “where the back of the upper front teeth enter the gums” (Farkas, 1999, p. 49).
Brass players have traditionally used speech to teach and learn the tongue movements necessary to play brass instruments. In his analysis of dystonic horn players, Iltis references the pedagogy of Eli Epstein and other brass teachers who use different vowel sounds to simulate playing in the low, middle, and high registers of the horn. When moving from lower to higher pitches, using an ô to an ē formation intuitively positions the tongue within the mouth (Iltis, et al., 2016, p.6). Different vowel sounds naturally lift or lower the tongue to precisely control the air speed going through the aperture, and therefore, the resulting pitch.
Consonant sounds are used for articulation. “Too” is commonly used for brass instruction, though “doo” or “loo” are often preferred for lighter and more rapid articulations. In each case, the letters /t,d, and l/ are used interchangeably as they fit the desired musical nuance. In speech, letters /t/, d, and l/ are all formed by lifting the tip of the tongue to the gum ridge, in an upward motion to the point described by Farkas (1999, p. 49).
While the muscles and muscle function involved in speech, swallowing and the brass embouchure are closely related, there is limited research regarding orofacial myofunctional disorders and their effect on brass playing. Schade (2007) acknowledges the muscular relationship between speech and instrumental playing, saying “the complexity of facial and oral muscle coordination in speech production is likewise reflected in music performance by wind instrumentalists” (p. 48). Prensky, Shapiro, and Silverman (1986) note that the highly destructive nature of tongue thrust might be considered reason to avoid playing any such musical instrument that might exacerbate the habit (p. 200). Yeo, Pham, Baker, and Porter (2002) identifies tongue thrusting habits as an orofacial myofunctional problem that compromises embouchure formation for musicians (p. 3). None of these assertions, however, had any kind of imaging to illustrate how such habits might affect a brass musician while playing the instrument. Such images and video could help to make the player aware of their muscular habits and guide subsequent orofacial myofunctional therapy.
Iltis et al. (2016) uses recent developments in RT-MRI to capture and quantify the movement patterns of brass players in his discussion of embouchure dystonia (Iltis, p.2). Similarly, this study uses RT-MRI video of an elite professional horn player to compare the playing strategy used by an elite player to the maladaptive brass playing strategies used by those with orofacial myofunctional disorders, specifically, tongue thrust. Speech and horn exercises are used to examine if subjects will have similar muscular dysfunction in both speech and horn playing. Additionally, RT-MRI visual feedback exercises are used to determine whether an OMD subject can learn new movement patterns while watching themselves play. It is helpful for OMD patients to be able to visualize what is actually occurring within the oral cavity during performance. While RT-MRI allows this to be done retrospectively after recording an exercise, the efficacy of making observations and adjustments of tongue positioning during performance is unknown and has not been used in previous research. Dr. Jens Frahm and his colleagues at the Max Planck Institute have recently developed a method of obtaining this type of visual feedback and it is included as an analytical tool in this study.
METHODS
Three horn players with diagnosed tongue- thrusts and varying amounts of orofacial myofunctional therapy completed horn and speech exercises during RT-MRI image acquisition. This study focused on an OMD subject, who completed the second year of a master’s degree in horn performance during the testing period. The teacher of the OMD subject reported fundamental issues with the OMD subject’s technique, including limited range and unclear articulation. Prior to imaging, the OMD subject completed a formal orofacial myofunctional evaluation with a certified speech therapist and orofacial myologist (author P.K.F.) who confirmed the presence of a tongue-thrust and no frenulum restrictions. The tongue-thrust caused negative orofacial habits, including open-mouth breathing, speech errors with /l, t, d, n, s, z, ch, sh, &dz/ sounds, and tensing of muscles when chewing and swallowing. The OMD subject received no OMD therapy before the first set of testing, and then followed a course of OMD therapy for 6 months before the second set of testing.
The OMD subject performed both speaking and horn exercises. The speaking exercise consisted of the spoken syllable “doo,” iterated at a tempo of 80 beats per minute (see Figure 1). “Doo” was selected since /d/ is one of the consonants consistently and negatively impacted by OMD. For subsequent comparison, a non-OMD control subject (CON) was also studied performing the same exercise.
The horn performance exercise consisted of playing a sustained concert Eb4 in the staff at a dynamic of pianissimo. This was one of the exercises used by the performers in Iltis’s (2016) study of elite and dystonic horn players (p. 2), and was chosen to allow comparison of an elite subject in that study to the OMD subject in the current experiment. The elite horn player holds a tenured position in an internationally recognized orchestra. The exercises were performed on an MRI-compatible natural horn (Richard Seraphinoff, Bloomington, IN), which has been previously described (Iltis, 2016, p. 2).
After performing the horn exercise, the OMD subject experienced a visual feedback session during the second set of imaging. While lying supine within the scanner, a mirror attachment allowed the subject to see a video monitor positioned opposite and facing the scanner. An RT-MRI image of an elite horn subject performing the same exercise was shown, which was a still frame that represented the tongue position of the elite subject during the sustain of the Eb4. Over several trials, the OMD subject attempted to emulate the tongue position of the elite horn subject while watching MRI video of their own movements in real time. The published guidelines established by the local ethics committee at the Max Planck Institute in Göttingen, Germany, were strictly followed, and all subjects submitted written informed consent in compliance with the regulations established by this committee.
Real-Time (RT) MRI
Methodological details of the MRI technology employed in this study have been published previously and are only summarized here. A 3T MRI system (Magnetom Prisma, Siemens Healthcare, Erlangen, Germany) using a 64- channel head coil was used to obtain the images. RT-MRI techniques have been previously described, (Uecker, 2010). In this study, serial MRI images were recorded at a rate of 30fps, yielding in-plane resolution of 1.5mm, slice thickness of 10mm, FOV = 192×19 mm2, and base resolution of 128×128mm2. Movies and images were obtained in a mid-sagittal orientation to cover tongue movements. Typical horn playing tasks yielded roughly 900 images per exercise. An MR-compatible optical microphone (Dual Channel- FOMRI, Optoacoustics, Or Yehuda, Israel) was attached to the bell of the horn outside the bore of the magnet and sound recordings were synchronized to image acquisition, as described by Niebergall et al. (2013, p. 477). The audio track for the harmonic sequence exercises was examined using standard audio-processing software (Audacity:http://audacity.sourceforge.net) to determine the moment of note changes within each exercise. In this way, the frame numbers capturing each note duration in the RT-MRI films could be identified.
Data Analysis and Statistical Procedures
To obtain quantitative information from RT-MRI films, we utilized a custom RT-MRI toolbox for MATLAB (MATLAB R2014a, Natick, MA, including the Image Processing and Signal Processing Toolboxes). This program analyzes the space within the oral cavity using strategically positioned profile lines. These lines allow the detection of differences in pixel luminescence along their length, thus depicting “edges” between bright pixels (tissue) and dark pixels (space or bone). This study employed one profile line, oriented to measure the distance between the edge of the inner lower lip and the tip of the tongue (see Figure 2).
The left panel shows a side view of the CON subject with the horizontal profile line in position. The right panel depicts changes in luminescence along this profile line (now in close-up view, rotated clockwise) across time during the exercise. The position of the vertical line is half-way between the 2nd and 3rd iteration of “doo.” The dark space between the dark/light luminescence edges represents the distance mentioned above.
Figure 2.
Control (CON) subject speaking “doo”, middle of 2nd iteration. The horizontal line in the left panel is the profile line. The right panel depicts a close-up image of the line with respect to time, rotated clockwise.
RESULTS
Speech
Comparison of the OMD subject’s muscular tendencies during speech to those of the CON subject reveals a forward tongue position and very limited muscular independence from the jaw. In every exercise, the OMD subject kept the tongue forward and against the bottom front teeth when articulating and sustaining sound. While the dorsal part of the tongue could rise to some degree for certain syllables, the muscle could not lift and move independently of the jaw. Figure 3 illustrates how the gap between the inner lip and tongue tip is much smaller for the OMD subject than for the CON subject in Figure 2. The visible dark area between pixels ~13 and ~16 in Figure 3 essentially represents the width of the teeth, illustrating no tongue retraction whatsoever. Finally, Figure 4 provides measurements of the average distance between the inner lip and the anterior edge of the tongue during the sustained periods of all 3 notes.
Horn
The OMD subject showed the same low and forward tongue position while playing the horn. In every exercise, the OMD subject’s tongue remained forward against the bottom front teeth for the duration of the note (see Figure 5, left panel). This positioning appeared to cause several technical performance issues, including a bunched chin and a pocket of air between the lower lip and lower front teeth. The elite horn subject withdrew and lifted the tongue away from the teeth immediately after articulating, demonstrating great independence between the tongue muscle and the jaw. The elite horn subject maintained a flat chin and no air between the lips and teeth. The amount to which the tongue retracted from the teeth varied with the register and dynamic of the note played (see Figure 5, right panel).
Real-Time Feedback
A monitor in the MRI chamber showed a still image of the elite horn subject playing a concert Eb4 next to a display of the OMD subject’s real-time MRI feedback. The OMD subject attempted to match the Eb4 tongue position of the elite horn subject while viewing their own RT-MRI video during playing. In several trials, the OMD subject was ultimately able to retract the tongue from the teeth, however, they could not lift the tongue independently from the jaw. This resulted in the tongue withdrawing too far in the oral cavity and compromising airflow from the throat (see Figure 6).
Figure 5.
Sagittal view of the OMD subject (left panel) sustaining a concert Eb4 with low, forward tongue position against the bottom front teeth. The elite subject (right panel) displays a raised, retracted tongue while playing the same note.
DISCUSSION
The Connection Between Speech and Horn The OMD subject’s consistently low and forward tongue position during all exercises suggests that orofacial myofunctional disorders create maladaptive muscular movements in both speech and horn playing. Iltis et al. (2016) notes the use of speech in the teaching of horn pedagogue Eli Epstein. Epstein describes the tongue movements in horn playing as similar to systematic adjustments associated with sounds in speech, so as to create faster and slower columns of air and higher and lower resulting frequencies (p. 6). The OMD subject’s inability to lift and retract the tongue in speech and in horn playing suggests that the speech and horn facilities are connected in the way suggested by Epstein. These deficiencies in tongue movement and positioning ultimately limited control of airflow, resulting in pockets of air between the lips and lower anterior teeth, a bunched chin, and a raspy sound.
Real-Time Feedback as Teaching Tool The RT-MRI feedback trials pose interesting considerations for muscular therapy and training. The OMD subject was more successful in emulating the tongue position of the elite horn subject while viewing feedback of their own compromised habits, specifically addressing their low and forward tongue position. While the OMD subject struggled to maintain a steady position for more than a few seconds, there were several moments when they stopped pushing their tongue against their front teeth, resulting in a flatter chin and less air between the lips and the lower anterior teeth (see Figure 7). These are attributes of a quality embouchure exhibited by the elite horn subject and described by Farkas (1999, p. 26).
While regular RT-MRI training sessions are not easily feasible, RT-MRI video feedback has proven to be a powerful tool to create awareness of muscular dysfunction. These feedback trials can also inform and guide future orofacial myofunctional therapy, since the most problematic movement problems are revealed in the process. In the OMD subject’s case, exercises that specifically target the retracting and lifting functions of the tongue would create the greatest impact on speech and horn playing facility. For instance, orofacial myologists often train proper tongue rest posture with neon elastic bands such as those used for orthodontia. Tongue-thrust patients lift and hold these elastics against the alveolar ridge for prescribed periods of time, building the muscular ability to lift to the palate and the habit of staying there when at rest (see Figure 8). Such an exercise could potentially grant physical abilities that, when paired with real-time awareness, would allow the OMD subject to match and learn the muscle strategies of elite horn players.
Figure 7.
Sagittal view of the OMD subject during a real-time MRI feedback trial, achieving a more natural, lifted tongue posture while playing concert Eb4. The tongue is not curled and pushing against the anterior bottom teeth, nor excessively withdrawn and closing the throat.
CONCLUSIONS
RT-MRI films provide insight regarding the movement strategies of individuals with orofacial myofunctional disorders. These films demonstrate similar maladaptive muscular movements in both speech and horn playing. Further research should examine a greater variety of speech samples, specifically how the formation of vowel sounds relates to changes in oral cavitation while playing the horn. Such information would provide insight into what orofacial myofunctional therapy would most benefit horn playing technique.
Competing Interests
J. Frahm holds a patent about the RT-MRI acquisition and reconstruction technique used here.
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© 2017 by the author. 2017 Natalie Douglass, Peter W. Iltis, Jens Frahm, Dirk Voit, Arun A. Joseph and Patricia K. Fisher