Lessac-Madsen Resonant Voice Therapy (LMRVT): A Brief Description and Review
Elvadine R. Seligmann
Summer Vocology Institute 2005
Denver, CO USA
Introduction
This paper discusses the technique known as Lessac-Madsen Resonant Voice Therapy (LMRVT) as designed and implemented by Dr. Katherine Verdolini. First, the reader will become acquainted with the origins of LMRVT and a basic overview of the technique itself. Next, the author will evaluate the technique based on biomechanics, learning and compliance standards. A discussion will follow regarding the effectiveness of LMRVT according to available literature and unpublished efficacy studies provided by Dr. Verdolini.
Verdolini developed LMRVT in the early 2000’s, naming it honor of two mentors, Dr. Arthur Lessac and Dr. Mark Madsen (Verdolini, 2002). Their pioneering in the areas of resonant voice and motor-learning respectively are the foundation of LMRVT.
LMRVT is unique in that it corrects both hypo- and hyperadducted vocal fold posturing by guiding vocal behavior toward barely-abducted or barely-adducted laryngeal posturing. Most voice patients, regardless of their diagnosis, share two common goals: (1) a strong, clear voice; and (2) the prevention of further vocal injury (Verdolini, 2002). A study led by Berry indicates that a barely ab/adducted glottal width of .6 mm produces maximum intraglottal pressure while minimizing impact stress to the vocal folds (Berry, Verdolini, Montequin, Hess, Chan & Titze, 2001). Intraglottal pressure corresponds to vocal strength or intensity, and vocal impact stress corresponds with vocal injury. Thus, the barely-ab/adducted laryngeal posturing favored in LMRVT is ideal for meeting patient goals of clear voice and limiting vocal injury (Verdolini-Marston, Drucker, Palmer & Samawi, 1998). Further, clinical practice and unpublished experimental data collected by Verdolini et al, strongly indicates that the use of resonant voice as prescribed by LMRVT is statistically more effective in healing phonotraumatic lesions than vocal rest (Verdolini, personal communication, July 12, 2005).
Although multiple visual and quantitative methods of measuring vocal fold adduction have been defined and utilized experimentally, they are too invasive to be useful during voice therapy. Additionally, quantitative measures, such as closed quotient measured by EGG, may be consistent in normal subjects, but tend to be skewed and unreliable in pathologic subjects due to a wide variety of variables related to the pathologies themselves (Peterson, Verdolini-Marston, Barkmeier & Hoffman, 1994). To complicate matters further, Titze proposes that the benefits of the barely-ab/adducted vocal fold posturing may be highly dependent upon the area of the epilarynx tube (Titze, 2002).
LMRVT circumvents these issues by using perceptual measures to guide patients toward the target behavior, which is resonant voice (Titze & Verdolini, in preparation). Resonant voice is characterized by vibratory sensations along the anterior alveolar ridge and a feeling of phonatory “ease.” If a patient can feel the forward vibrations and production feels easy, the patient is producing a resonant voice quality. This quality corresponds to the barely ab/adducted vocal fold posturing (Verdolini 2000).
In its most basic form, resonant voice is the basic training gesture (BTG) of LMRVT. Following a series of basic body stretches, the clinician guides the patient in full-body introspection and observation in order to achieve the patient’s best representation of resonant voice. This guidance follows the scan-gel-show-tell principle, which involves attention to self-awareness, physical manipulation, demonstration, and as a last resort, telling the patient what to change, until the patient exhibits his/her best possible resonant voice quality (Verdolini & Titze, in preparation). Once the patient can identify the sensations associated with the target behavior, significant time is spent exploring resonant voice on simple phonemes. Specially designed bridging exercises gradually add more complicated voicing patterns to the BTG until the patient is able to produce normal, conversational speech using resonant voice (Verdolini, 2004). Finally, the patient is guided in applying resonant voice to louder phonation and other challenging situations specific to the patient’s lifestyle (Verdolini & Titze, in preparation). The clinician also focuses on the patient’s use of inflection during early exercises so that the resonant voice behavior becomes truly accessible to the patient in his/her daily life (Verdolini, 2004). The patient should exhibit evidence of improved voice quality and reduced phonatory effort within the first session to justify continuing with this method of therapy (Verdolini & Titze, in preparation).
In addition to resonant voice exercises, the clinician builds a voice hygiene program specific to each patient (Verdolini, 2002). Although there is no significant data indicating the effectiveness of vocal hygiene in hypo- and hyperadductive patients, certain behavioral modifications can support the work done in LMRVT. Specifically, adequate hydration can help to minimize the effects of phonotrauma (Verdolini, 2004). Hydration also reduces the lung pressure required for vocal fold oscillation, which the patient recognizes as decreased effort (Verdolini-Marston, Sandage & Titze, 1994). Screaming involves hyperadduction combined with unusually high amplitudes of vibration resulting in significant, sometimes life-changing levels of vocal injury (Verdolini, 2002). Patients are instructed to speak in moderate voice until the clinician advises they are ready to apply the principles of resonant voice to louder phonation. Reflux symptoms, though not directly related to adduction issues, should be treated if indicated in order to decrease the risk of additional phonotrauma (Verdolini, 2004).
Verdolini recommends delivering LMRVT in 45-minute weekly sessions for 8 weeks, although other schedules may be used as appropriate for the patient’s schedule or lifestyle. During the final therapy session, the clinician and patient devise a self-treatment schedule to facilitate the patient’s continued progress following therapy (Verdolini, 2004).
As previously stated, LMRVT is unique in that it applies to voice disorders related to both hypo- and hyperadduction, and it is an all-inclusive therapy program that addresses voice hygiene, voice modification and post-therapy self-care. It is further distinct in its foundation not only in biomechanics, but also in learning science and compliance research, or as Verdolini calls them, “the what,” “the how,” and “the if” (Verdolini& Titze, in preparation).
The “what” includes the hygiene program and the resonant voice therapy itself as discussed above. It is the physiological training of resonant voice in order to facilitate the barely ab/adducted vocal fold posturing which multiple studies have indicated yields the greatest vocal intensity with the least vocal injury (Verdolini& Titze, in preparation). This biomechanical target is the primary goal of LMRVT. Functional goals, such speaking with a clear, strong voice with little effort, and medical goals, such as the reduction of lesions, are often by-products of a therapy program that focuses on biomechanical issues (Verdolini, 2000). However, in some cases the clinician may address other issues that prevent complete voice rehabilitation.
The “how” refers to the process by which the patient learns the new manner of producing speech. Significant research has been done in the area of motor learning indicating that attention to the mechanics of a motor skill, such as the production of resonant voice, impairs the patient’s immediate performance and long-term retention of the skill. Similar results are attributed to the use of mechanical instructions (Verdolini, 2004). This is why the clinician appeals first to the patient’s own sensory awareness when aiming for resonant voice, using verbal instructions only when sensory methods fail. The patient is instructed to notice how their voice production makes them feel rather than what they do to accomplish it (Verdolini & Titze, in preparation). Verdolini has applied further research that strongly indicates that to maximize long-term learning, the clinician must limit the amount of feedback they offer to the patient. Tenets of random and variable practice also apply to LMRVT in concurrence with research indicating their benefits to long-term learning (Verdolini, 2004). All of this applies to voice therapy because clinicians want their patients to retain and use therapy techniques to improve their voices long-term, not only in the clinic. LMRVT’s attention to “the how” is perhaps the most striking feature that sets it apart from other therapies targeting similar patients.
The “if” of LMRVT refers to patient compliance. Voice therapy is useless if the patient refuses to implement the new skills outside the clinic. In fact, a study led by Verdolini comparing LMRVT to “confidential voice therapy” strongly indicated that patient compliance was a better indicator of therapy effectiveness than the type of therapy administered (Verdolini-Marston, Burke, Lessac, Glaze & Caldwell, 1995). In response to these findings, Verdolini’s program focuses on patient individuality and integration into the patient’s existing lifestyle in order to increase patients’ willingness to apply therapy concepts to life outside the clinic. The hygiene program is tailor-made for each patient, stressing points of hygiene that are specifically relevant to the patient, rather than enforcing a long list of do’s and don’ts. The clinician integrates resonant voice practice into each patient’s daily routine, and everything the patient needs to know in order to stay on task outside the clinic is provided in writing (Verdolini, 2002). The patient contributes to the formation of his/her own post-therapy program to ensure that it takes into account his/her individual lifestyle and post-therapy needs (Verdolini, 2004). Most importantly, the use of resonant voice transfers readily to loud speech, so patients don’t have to compromise the strength of their daily performance in order to comply with the therapy structure (Verdolini, 2002). There may be a downside, however. The aforementioned study led by Verdolini showed the possibility that some inspired patients may attempt loud voice outside the clinic before they have mastered more basic resonant voice exercises, thus causing further vocal injury (Verdolini-Marston, Burke, Lessac, Glaze & Caldwell, 1995). A new study measuring this possible trend would be necessary to speak conclusively about this theory.
Although clinical data strongly indicates the effectiveness of LMRVT, limited study has been performed to validate the program statistically. One recent, unpublished study (N=40) by Verdolini simultaneously compared long-term effects of learning motor skills by: 1) focusing on metaphoric instructions versus sensory feedback, and 2) variable versus non-variable practice. Results indicated that sensory learning produced better long-term results than metaphoric learning, and variable practice produced better long-term results than non-variable practice (Verdolini, personal communication, July 12, 2005). Sensory learning and variable practice are core components of the LMRVT program, suggesting that learning results should be optimal.
Another recent and unpublished study (N=9) by Verdolini focuses on the effects of LMRVT on wound healing. Experimenters collected secretions from the surface of subjects’ vocal folds before and after strenuous vocal activity. Subjects were then randomly assigned to a therapy group for either complete voice rest, resonant voice exercises, or spontaneous speech. The study yielded statistically significant results indicating that while voice rest was a healing therapy, LMRVT led to more complete vocal fold healing in a shorter period of time than voice rest or spontaneous speech (Verdolini, personal communication, July 12, 2005). These results strongly support the use of LMRVT to heal phonotraumatic lesions versus the commonly recommended prescription of complete voice rest.
These studies both reflect favorably on the LMRVT program as a valid and effective method of voice therapy. However, no studies have yet been conducted which provide statistically significant data comparing LMRVT to other popular methods of treating voice disorders characterized by hypo- and hyperadducted vocal folds. The absence of data comparing learning, compliance, and consistency in meeting biomechanical, medical and functional goals by LMRVT versus other popular therapies is necessary to determine if LMRVT is the most effective treatment for patients suffering from these disorders.
LMRVT stands out from many other voice therapy programs because it addresses the needs of a variety of patients, and it is deeply rooted in principles of biomechanics, cognitive learning science and compliance. There is little question that LMRVT is an effective treatment for patients with hypo- and hyperadducted vocal fold configurations. What remains to be seen is whether or not LMRVT is the best therapy on the market, and whether or not it can be improved.
References
Berry, D.A., Verdolini, K., Montequin, D.W., Hess, M.M., Chan, R.W., & Titze, I.R. (2001). A quantitative output-cost ration in voice production. Journal of Speech, Language and Hearing Research, 44, 29-37.
Peterson, K. L., Verdolini-Marston, K., Barkmeier, J. M., & Hoffman, H.T. (1994). Comparison of aerodynamic and electroglottographic parameters in evaluating clinically relevant voicing patterns. Ann Otol Rhinol Otolaryngol, 103, 335-346.
Titze, I.R. (2002). Regulating glottal airflow in phonation: Application of the maximum power transfer theorem to a low-dimensional phonation model. Journal of the Acoustical Society of America, 111, 367-376.
Titze, I.R. & Verdolini, K. (in preparation). Vocology.
Verdolini, K. (2000). Case Study: Resonant Voice Therapy. In J. Stemple, Voice therapy: Clinical
Studies (2nd ed., pp.46-62). San Diego: Singular Publishing
Group, Inc.
Verdolini, K. (2004). Lessac-Madsen Resonant Voice Therapy. Training manual and patient materials distributed at Summer Vocology Institute, Denver, CO, July, 2005.
Verdolini, K. (2002). Lessac-Madsen Resonant Voice Therapy: Sensory Processing – Broad Practice. University of Pittsburgh.
Verdolini-Marston, K., Burke, M.K., Lessac, A., Glaze, L., & Caldwell, E. (1995). Preliminary study of two methods of treatment for laryngeal nodules. Journal of Voice, 9, 74-85.
Verdolini-Marston, K., Drucker, D.G., Palmer, P.M., & Samawi, H. (1998). Laryngeal adduction in resonant voice. Journal of Voice, 12, 315-327.
Verdolini-Marston, K., Sandage, M., & Titze, I.R. (1994). Effect of hydration treatment on laryngeal nodules and polyps, and related voice measures. Journal of Voice, 8, 30-47.