The Vocal Aerodynamic Change in Female Patients With Muscular Tension Dysphonia After Voice Training *Fa-Ya Liang, *Jin-Shan Yang, †Xiang-Sheng Mei, *Qian Cai, *Zhong Guan, *,‡Bi-Ru Zhang, *Ya-Jing Wang, *Jian Gong, *Xiao-Ming Huang, *Jie-Ren Peng, and *Yi-Qing Zheng, *Guangzhou, yZhengzhou, and zFoshan, People’s Republic of China
Summary: Objective. To investigate the changes of vocal aerodynamics indicators after voice training in female patients with muscular tension dysphonia (MTD). Methods. Twenty-one female MTD patients (before voice training and 12 weeks after voice training) and 20 female volunteers with normal voices (the control group) received vocal aerodynamic analysis. Parameters included subglottal pressure (SGP), aerodynamic power (AP), mean expiratory airflow (MEA), and maximum phonation time (MPT) were recorded and analyzed by phonatory aerodynamic system. Results. Before voice training, the median SGP and mean AP were higher than control group, whereas median MPT was shorter, and these differences were statistically significant. After 12 weeks of voice training, the median SGP and mean AP were decreased and the median MPT was increased compared with the measurements obtained before training, and these differences were statistically significant. The differences of median SGP, mean AP, mean MEA, and median MPT between MTD after 12 weeks of training and control group were not statistically significant. Conclusion. Voice training is an effective treatment for MTD patients. Aerodynamic analysis can effectively evaluate the vocal functional status of MTD patients before and after training, which is beneficial for the treatment efficacy evaluation. Key Words: Muscular tension dysphonia–Vocal aerodynamic analysis–Voice training. INTRODUCTION Muscular tension dysphonia (MTD), also known as hyperfunctional dysphonia, is a voice disorder caused by repeated contraction of the throat muscle due to excessive or incorrect use of the voice and commonly seen in female patients.1–4 MTD is characterized by normal anatomy of the vocal organs; this disorder results from functional incoordination among vocal organs resulting from incorrect vocal behaviors such as long-term strong and excessive force.1 The pathogenesis of MTD remains unclear. Our previous study demonstrated that excessively strong laryngeal function is the primary vocal aerodynamic characteristic of MTD patients, indicating that the subglottal pressure (SGP) and the glottal resistance are increased, the mean expiratory airflow (MEA) is reduced, and the maximum phonation time (MPT) is reduced.5 Voice training is an important treatment option for MTD that has been well developed in many foreign countries,6 but it is not yet popularized in China. Voice training and throat massage can reduce the throat discomfort and the tension of neck muscles for Accepted for publication November 26, 2013. The authors F.-Y.L., J.-S.Y., and X.-S.M. contributed equally to this work. This work was supported by Science and Technology Planning Project of Guangdong province, China (2010B060900050; 2011B010200024). From the *Department of Otorhinolaryngology—Head and Neck Surgery, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, People’s Republic of China; yDepartment of Otorhinolaryngology, The First Affiliated Hospital of Henan University of Traditional Chinese Medicines, Zhengzhou, People’s Republic of China; and the zDepartment of Otorhinolaryngology, The First People’s Hospital of Shunde, Foshan, People’s Republic of China. Address correspondence and reprint requests to Yi-Qing Zheng, Department of Otorhinolaryngology—Head and Neck Surgery, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou 510120, People’s Republic of China. E-mail: yiqingzheng@ hotmail.com Journal of Voice, Vol. 28, No. 3, pp. 393.e7-393.e10 0892-1997/$36.00 Ó 2014 The Voice Foundation http://dx.doi.org/10.1016/j.jvoice.2013.11.010
MTD patients and improve their voice quality.7,8 However, no study focusing on the changes in vocal aerodynamics indicators after voice training has been reported in MTD patients. Based on our previous study,5 we compared and analyzed a number of vocal aerodynamic indicators in 21 female patients with MTD and 20 normal female adults before and 12 weeks after voice training to explore the effect of voice training on the laryngeal function of MTD patients. MATERIALS AND METHODS Test subjects Patient group. All MTD female patients were outpatients at the Department of Otolaryngology of Sun Yat-sen Memorial Hospital from January 2011 to May 2013. This study included 21 female patients, with a median age of 34 years (18–48 years). The inclusion criteria consisted of the following: symptoms of dysphonia (ie, patients complaining of abnormal vocalization, hoarseness, vocal fatigue, and so forth); excessive force vocal behavior (ie, high levels of tension in the neck muscles when voicing, which could be associated with external jugular vein distention or thickening in the root of the neck, a high-held larynx position, palpable tremors, and so forth); and no history of smoking. For all MTD patients, the results of laryngoscopy examination showed normal vocal shape and color, and no organic disease of the vocal fold was found. Other symptoms included squeezing of the bilateral vocal edges, a visible gap in the glottis area, excessive adduction of the plica vestibularis, extrusion of the throat, and sphincter-like changes in the throat due to excessive squeezing.2,3,7 All patients underwent voice training. Control group. The control group included 20 female volunteers, with a median age of 31 years (20–45 years). All cases in the control group produced normal sound, did not
393.e8 have a history of smoking, had not received professional vocal or singing training, and had no disease history in the throat or respiratory and nervous systems. The results of the laryngoscopy examination showed normal vocal shape, color, and movement. Voice training methods The voice training methods were applied for all patients for voice training, which included the following five components of exercise: exercise with a convex and concave abdomen; exercise for controlling the diaphragm with a convex abdomen; rapid breathing exercise; relaxation exercise for the muscles at the base of the tongue and throat; and a reciting vocal exercise. The entire voice training program lasted for 4 weeks. Group training was provided every Saturday morning, with six to 10 individuals in one group for a single 2-hour session. The patients were asked to self-practice during the weekdays and apply what they had learned in the class to everyday vocal communication. In the first 2 weeks, voice rest was emphasized, and the first four parts of the exercises were mainly performed. The reciting vocal exercise was added in the last 2 weeks of training. Breath exercise with a convex and concave abdomen. The patients were asked to stand naturally, with both eyes looking at the front horizontally. Their shoulders, chest, and arms were relaxed, which maintained the muscles of the shoulders, neck, jaw, and throat relaxed, and their hands were overlapping, with the palms placed 3 in below the belly button. When exhaling, the navel as well as the area below was forced inward strongly; when inhaling, the navel as well as the area below was projected outward strongly. The actions of exhaling and the inhaling were each conducted for 16 times per minute, and this practice was performed for 20 minutes each day. Exercise for controlling the diaphragm with a convex abdomen. The patients were asked to stand naturally. When inhaling, the navel as well as the area below was projected outward strongly and then the patients were asked to slowly and clearly make the ‘‘si’’ sound, whereas the convex state of the navel as well as the area below was remained. After a breath was exhausted, the patients would inhale with both the nose and the mouth and then begin to make another si sound. Each voicing of si was maintained for at least 30 seconds. This practice was performed for 20 minutes each day. Rapid breathing exercise. The patients were asked to stand naturally. The breath exercise with the convex and concave abdomen was executed rapidly, meaning that the actions of exhaling and inhaling were each conducted at least 50 times per minute, with each exercise lasting 1 minutes and performed five times a day. Relaxation exercise for the muscles at the base of the tongue and throat. The patients were asked to stand naturally, with the upper body leaning forward and both hands on the waist. The mouth was widely open, and the tongue was protruding out of the mouth. With the cervical axis, the head gently swung to drive the lashing of the tongue, such that the side of
Journal of Voice, Vol. 28, No. 3, 2014
the tongue could reach the left and right corners of the mouth. Each exercise lasted for 1 minute and was performed five times a day. (Note: Patients with severe cervical spondylosis were forbidden to perform this exercise.) Reciting vocal exercise. After the above four types of exercises were fully mastered, the actual exercise of vocal application was carried out. First, five-character Tang poetry was selected for slow reading to experience the feeling of the breath sounds. Then, seven-character Tang poetry, prose, and articles in newspapers were read with gradually accelerated speed that was close to or at the normal speed of standard communication speech. This practice was performed for 20 minutes each time. Testing methods The phonatory aerodynamic system model 6600 (KayPENTAX Corp, Lincoln Park, NJ) was used to detect the SGP, aerodynamic power (AP), MEA, and MPT for the above subjects. Before data acquisition, according to the correction system of the threshold value set by the instrument, the examinees were trained until they could comfortably execute the instructions. Measurement of the SGP and AP at the comfortable voicing state. An oral cavity catheter was inserted into the mouth of the examinee at approximately 2.5 cm, without the nozzle being blocked by the tongue or palate. The patient was asked to fasten the mask to the nose and mouth to avoid leakage and then the examinee was instructed to make a /pa-pa/ syllable using the comfortable sound, for five to seven successive times within a breath and one to two times per second. To ensure equal rhythm, participants were trained in each speaking task until they produced the syllable trains at the appropriate pace and were speaking at their comfortable loudness level. The first and last data points were abandoned, and the remaining data were automatically analyzed using the VOICING EFFICIENCY protocol. The values of the SGP and AP were recorded. Measurement of the MEA. The examinee was asked to fasten the mask to the nose and mouth to avoid leakage. Then, the examinee was instructed to make a /a/ syllable, with the sound intensity controlled at approximately 72 dB; each sound lasted for 5 seconds and was repeated three times, with 3–4 seconds of rest before each voicing. The stable data at the middle 5 seconds were automatically analyzed using the COMFORTABLE SUSTAINED PHONATION protocol. The values of MEA were recorded, and the final value was determined by the average of three measurements. Measurement of the MPT. The examinee was trained until they could comfortably execute the instructions, the instruction to take a deep breath, and a facial mask was used to cover the mouth and nose tightly without leakage. Subsequently, the subject was instructed to produce the vowel /a/ at a comfortable pitch and volume for as long as possible. The experiment was repeated three times. The results were analyzed using the MAXIMUM SUSTAINED PHONATION protocol. The
Fa-Ya Liang, et al
393.e9
Vocal Aerodynamic Changes in Female Patients With MTD
TABLE 1. The Aerodynamic Parameters of Female MTD Patients (Before and After 12-wk of Voice Training) and the Control Group Individuals Group
No.
Age (y)
SGP (cmH2O)
MPT (s)
MEA (L/S)
AP (W)
MTD before training MTD after 12-wk training Control group
21 21 20
34 (23; 41)* 34 (23; 41)* 31 (23; 39)
10.48 (8.45; 12.29)y,z 7.18 (5.42; 8.59)* 6.79 (4.93; 7.89)
12.51 (9.12; 16.91)y,z 21.62 (17.21; 24.96)* 23.67 (18.12; 26.92)
0.11 ± 0.04*,x 0.12 ± 0.03* 0.13 ± 0.03
0.14 ± 0.05y,z 0.09 ± 0.03* 0.08 ± 0.03
* Compared with control group, P > 0.05. y Compared with control group, P < 0.05. z Compared with MTD after 12-wk training, P < 0.05. x Compared with MTD after 12-wk training, P > 0.05.
longest time was collected, and the maximum value from three measurements was selected for further analysis. Statistical methods Data were analyzed with SPSS (version 18.0; Chicago, IL). Normal distribution variables were presented as mean ± standard deviation and nonnormal distribution variables were presented as median (P25; P75). The differences of normally distributed variables were determined by the t test and the nonnormally distributed data were determined by Mann– Whitney rank sum test. Values of P < 0.05 were considered significant. RESULTS The aerodynamic parameters of female MTD patients (before and after 12 weeks of voice training) and the control group individuals are listed in Table 1. Before voice training, the median SGP and mean AP was higher than that of the control group (SGP: 10.48 vs 6.79 cm H2O, Z ¼ 5.374, P < 0.01; AP: 0.14 vs 0.08 W, t ¼ 5.020, P < 0.01), whereas median MPT was shorter (12.51 vs 23.67 seconds, Z ¼ 5.295, P < 0.01), and these differences were statistically significant. Moreover, the mean MEA of MTD patients was less than that of the control group (0.11 vs 0.13 L/s, t ¼ 1.449, P ¼ 0.155), although the difference was not statistically significant. After 12 weeks of voice training, the median SGP and mean AP were decreased and the median MPT was increased compared with the measurements obtained before training, and these differences were statistically significant (SGP: 7.18 vs 10.48 cmH2O, Z ¼ 4.415, P < 0.01; AP: 0.08 vs 0.15W, t ¼ 4.029, P < 0.01; and MPT: 21.62 vs 12.51 seconds, Z ¼ 4.113, P < 0.01). In addition, the mean MEA of MTD patients was increased compared with the measurements obtained before training, although the difference was not statistically significant (0.12 vs 0.11 L/s, t ¼ 0.715, P ¼ 0.479). The differences of median SGP, mean AP, mean MEA, and median MPT between MTD after 12 weeks of training and control group were not statistically significant (SGP: 7.18 vs 6.79 cmH2O, Z ¼ 1.865, P ¼ 0.062; AP: 0.09 vs 0.08 W, t ¼ 0.899, P ¼ 0.374; MEA: 0.12 vs 0.13 L/s, t ¼ 1.339, P ¼ 0.188; and MPT: 21.62 vs 23.67 seconds, Z ¼ 1.930, P ¼ 0.054).
DISCUSSION The etiology of MTD is multifactorial but often includes dysphonia, which is caused by the misuse and abuse of the voice under certain predisposing factors. The clinical characteristics of MTD are also diverse, with the main symptoms including the following: a burning sensation in the throat; tight voice; laborious voicing; shallow breathing for sharp and high pitched sounds; an above-normal position of the larynx when voicing; tense muscles on the hyoid bone; the lack of organ disease in the vocal fold found by laryngoscopy examination; squeezing of the bilateral vocal edges when voicing; visible gap in the glottis area; excessive adduction of the plica vestibularis; extrusion of the throat; and sphincter-like change in the throat due to excessive squeezing.3,4,9 Because MTD patients present no organic disease in the vocal folds but their habits of voicing are incorrect, the treatment mainly consists of voice-based training supplemented with throat massage.6–8 The SGP refers to the lung pressure reaching the subglottic airway, which is one of the most common indicators in the study of aerodynamics10 and also the least disturbed of many aerodynamic indicators.11 In normal voice, the general SGP is only 5–8 cmH2O.12 The median value of SGP for the normal adults measured in this study was 6.55 cmH2O, which is consistent with the reported value. SGP may reflect the functional status of the throat and is related to the tension and the quality of the vocal fold. Our previous studies suggested that MTD patients have an excessively strong state of laryngeal vocal function and that their SGP is higher than that in normal controls (P < 0.01). The reason for this finding may be that tension in the laryngeal muscles of MTD patients leads to an increase in the quality and tension of the vocal folds, such that the vocal fold vibration is affected and the SGP needs to be increased to maintain the tension and vibration of the vocal fold. After 12 weeks of voice training, the SGP of the MTD patients was decreased, although it remained slightly higher than that of the normal control group, but this difference was not statistically significant (P > 0.05). This result suggested that voice training could reduce the tension of the laryngeal muscle and reduce the tension and quality of the vocal fold, such that the patients could maintain the vibration of the vocal fold through lower SGP. The MEA may reflect the closure status and the vocal intensity of the glottis. The examinees in this study were asked to
393.e10 maintain the sound intensity at approximately 72 dB to exclude the influence of sound intensity. After excluding this factor, the MEA was significantly correlated with the level of the glottis closure; if the level of the glottis closure decreased, the MEA was significantly increased, and vice versa. Kitajima13 reported that when the tension of the vocal fold increased (such as in spasmodic dysphonia), the MEA was decreased significantly. Because the majority of the MTD patients showed excessively strong contraction of the throat muscles, a high level of glottis closure, and increased vocal tension, the MEA was decreased. We also observed that the MEA of the MTD group was lower than that of the control group, although the difference was not statistically significant. The reason for this difference may be that the contractions of the cricoarytenoid muscle in some MTD patients were not synchronized between the front and back areas, such that they squeezed each other at the front area of the vocal fold and the gap in the glottis area could be observed under a laryngoscope. This incomplete glottis closure led to an abnormal increase in airflow rate. After the voice training, the excessively strong contraction of the laryngeal muscle in MTD patients was eased, the vocal tension was reduced, and the strength of the glottis closure was reduced; as a result, the MEA was higher than that before training and reached a level similar to the normal control group. The AP was obtained by the conversion of the SGP and the MEA. Our study showed that the AP of the MTD patients was higher than that of the normal control group, and this difference was statistically significant (P < 0.01). The occurrence of this phenomenon may be related to the method used to calculate AP. The SGP and MEA were both increased in patients with voice disorders, so the multiplication product of the two measurements was inevitably increased. Despite some MTD patients showing a decreased MEA, an increased result was still obtained when the result was multiplied with the SGP value. The increase in the AP suggests that the energy required for vocal sound is generally higher in MTD patients, that is, that speaking requires more effort. After 12 weeks of voice training, the tension of the laryngeal muscle in MTD patients was decreased, the vocal tension was reduced, and the SGP was significantly decreased, resulting in a decrease in AP. Altogether, these results indicate that MTD patients were able to speak with less effort following voice training. The MPT represents the longest duration of audible sound made by the examinee, and this aerodynamic indicator is associated with several factors including lung capacity, the degree of glottis closure, the breathing method, and breath control. Solomon et al14 proposed that the MPT is negatively correlated with the throat and airway resistance. The MPT of the MTD pa-
Journal of Voice, Vol. 28, No. 3, 2014
tients measured in this study was shorter than that of the control group, and this difference was statistically significant. The reason for this difference is related to the improper application of respiratory airflow and poor coordination when voicing in MTD patients. After voice training, the breathing habits of the MTD patients were re-established, and the respiratory system provided better support for the voicing process. As a result, the MPT was significantly improved and reached the level of the normal control subjects. In summary, voice training represents an effective treatment for MTD patients. Moreover, aerodynamic analysis can effectively evaluate the vocal functional status of MTD patients before and after training, which is beneficial for treatment efficacy evaluation. REFERENCES 1. Izadi F, Salehi A. Comparison between palpatory findings of the hyoid position and their acoustic, videostroboscopic, and perceptual attributes in patients with muscle tension dysphonia (with and without organic lesions). J Voice. 2013;27:78–83. 2. Morrison MD, Nichol H, Rammage LA. Diagnostic criteria in functional dysphonia. Laryngoscope. 1986;96:1–8. 3. Koufman JA, Blalock PD. Functional voice disorders. Otolaryngol Clin North Am. 1991;24:1059–1073. 4. Morrison MD, Rammage LA. Muscle misuse voice disorders: description and classification. Acta Otolaryngol. 1993;113:428–434. 5. Zheng YQ, Zhang BR, Su WY, Gong J, Yuan MQ, Ding YL, Rao SQ. Laryngeal aerodynamic analysis in assisting with the diagnosis of muscle tension dysphonia. J Voice. 2012;26:177–181. 6. Van Houtte E, Van Lierde K, Claeys S. Pathophysiology and treatment of muscle tension dysphonia: a review of the current knowledge. J Voice. 2011;25:202–207. 7. Mathieson L, Hirani SP, Epstein R, Baken RJ, Wood G, Rubin JS. Laryngeal manual therapy: a preliminary study to examine its treatment effects in the management of muscle tension dysphonia. J Voice. 2009;23: 353–366. 8. Van Lierde KM, De Bodt M, Dhaeseleer E, Wuyts F, Claeys S. The treatment of muscle tension dysphonia: a comparison of two treatment techniques by means of an objective multiparameter approach. J Voice. 2010; 24:294–301. 9. Morrison MD, Rammage LA, Belisle GM, Pullan CB, Nichol H. Muscular tension dysphonia. J Otolaryngol. 1983;12:302–306. 10. Bard MC, Slavit DH, McCaffrey TV, Lipton RJ. Noninvasive technique for estimating subglottic pressure and laryngeal efficiency. Ann Otol Rhinol Laryngol. 1992;101:578–582. 11. Goozee JV, Murdoch BE, Theodoros DG, Thompson EC. The effects of age and gender on laryngeal aerodynamics. Int J Lang Commun Disord. 1998; 33:221–238. 12. Baken RJ, Orlikoff RF. Clinical Measurement of Speech and Voice. Independence, KY: Cengage Learning; 2000:297–331. 13. Kitajima K. Airflow study of pathologic larynges using a hot wire flowmeter. Ann Otol Rhinol Laryngol. 1985;94(2 pt 1):195–197. 14. Solomon NP, Garlitz SJ, Milbrath RL. Respiratory and laryngeal contributions to maximum phonation duration. J Voice. 2000;14:331–340.
Summary: Objective. To investigate the changes of vocal aerodynamics indicators after voice training in female patients with muscular tension dysphonia (MTD). Methods. Twenty-one female MTD patients (before voice training and 12 weeks after voice training) and 20 female volunteers with normal voices (the control group) received vocal aerodynamic analysis. Parameters included subglottal pressure (SGP), aerodynamic power (AP), mean expiratory airflow (MEA), and maximum phonation time (MPT) were recorded and analyzed by phonatory aerodynamic system. Results. Before voice training, the median SGP and mean AP were higher than control group, whereas median MPT was shorter, and these differences were statistically significant. After 12 weeks of voice training, the median SGP and mean AP were decreased and the median MPT was increased compared with the measurements obtained before training, and these differences were statistically significant. The differences of median SGP, mean AP, mean MEA, and median MPT between MTD after 12 weeks of training and control group were not statistically significant. Conclusion. Voice training is an effective treatment for MTD patients. Aerodynamic analysis can effectively evaluate the vocal functional status of MTD patients before and after training, which is beneficial for the treatment efficacy evaluation. Key Words: Muscular tension dysphonia–Vocal aerodynamic analysis–Voice training. INTRODUCTION Muscular tension dysphonia (MTD), also known as hyperfunctional dysphonia, is a voice disorder caused by repeated contraction of the throat muscle due to excessive or incorrect use of the voice and commonly seen in female patients.1–4 MTD is characterized by normal anatomy of the vocal organs; this disorder results from functional incoordination among vocal organs resulting from incorrect vocal behaviors such as long-term strong and excessive force.1 The pathogenesis of MTD remains unclear. Our previous study demonstrated that excessively strong laryngeal function is the primary vocal aerodynamic characteristic of MTD patients, indicating that the subglottal pressure (SGP) and the glottal resistance are increased, the mean expiratory airflow (MEA) is reduced, and the maximum phonation time (MPT) is reduced.5 Voice training is an important treatment option for MTD that has been well developed in many foreign countries,6 but it is not yet popularized in China. Voice training and throat massage can reduce the throat discomfort and the tension of neck muscles for Accepted for publication November 26, 2013. The authors F.-Y.L., J.-S.Y., and X.-S.M. contributed equally to this work. This work was supported by Science and Technology Planning Project of Guangdong province, China (2010B060900050; 2011B010200024). From the *Department of Otorhinolaryngology—Head and Neck Surgery, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, People’s Republic of China; yDepartment of Otorhinolaryngology, The First Affiliated Hospital of Henan University of Traditional Chinese Medicines, Zhengzhou, People’s Republic of China; and the zDepartment of Otorhinolaryngology, The First People’s Hospital of Shunde, Foshan, People’s Republic of China. Address correspondence and reprint requests to Yi-Qing Zheng, Department of Otorhinolaryngology—Head and Neck Surgery, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou 510120, People’s Republic of China. E-mail: yiqingzheng@ hotmail.com Journal of Voice, Vol. 28, No. 3, pp. 393.e7-393.e10 0892-1997/$36.00 Ó 2014 The Voice Foundation http://dx.doi.org/10.1016/j.jvoice.2013.11.010
MTD patients and improve their voice quality.7,8 However, no study focusing on the changes in vocal aerodynamics indicators after voice training has been reported in MTD patients. Based on our previous study,5 we compared and analyzed a number of vocal aerodynamic indicators in 21 female patients with MTD and 20 normal female adults before and 12 weeks after voice training to explore the effect of voice training on the laryngeal function of MTD patients. MATERIALS AND METHODS Test subjects Patient group. All MTD female patients were outpatients at the Department of Otolaryngology of Sun Yat-sen Memorial Hospital from January 2011 to May 2013. This study included 21 female patients, with a median age of 34 years (18–48 years). The inclusion criteria consisted of the following: symptoms of dysphonia (ie, patients complaining of abnormal vocalization, hoarseness, vocal fatigue, and so forth); excessive force vocal behavior (ie, high levels of tension in the neck muscles when voicing, which could be associated with external jugular vein distention or thickening in the root of the neck, a high-held larynx position, palpable tremors, and so forth); and no history of smoking. For all MTD patients, the results of laryngoscopy examination showed normal vocal shape and color, and no organic disease of the vocal fold was found. Other symptoms included squeezing of the bilateral vocal edges, a visible gap in the glottis area, excessive adduction of the plica vestibularis, extrusion of the throat, and sphincter-like changes in the throat due to excessive squeezing.2,3,7 All patients underwent voice training. Control group. The control group included 20 female volunteers, with a median age of 31 years (20–45 years). All cases in the control group produced normal sound, did not
393.e8 have a history of smoking, had not received professional vocal or singing training, and had no disease history in the throat or respiratory and nervous systems. The results of the laryngoscopy examination showed normal vocal shape, color, and movement. Voice training methods The voice training methods were applied for all patients for voice training, which included the following five components of exercise: exercise with a convex and concave abdomen; exercise for controlling the diaphragm with a convex abdomen; rapid breathing exercise; relaxation exercise for the muscles at the base of the tongue and throat; and a reciting vocal exercise. The entire voice training program lasted for 4 weeks. Group training was provided every Saturday morning, with six to 10 individuals in one group for a single 2-hour session. The patients were asked to self-practice during the weekdays and apply what they had learned in the class to everyday vocal communication. In the first 2 weeks, voice rest was emphasized, and the first four parts of the exercises were mainly performed. The reciting vocal exercise was added in the last 2 weeks of training. Breath exercise with a convex and concave abdomen. The patients were asked to stand naturally, with both eyes looking at the front horizontally. Their shoulders, chest, and arms were relaxed, which maintained the muscles of the shoulders, neck, jaw, and throat relaxed, and their hands were overlapping, with the palms placed 3 in below the belly button. When exhaling, the navel as well as the area below was forced inward strongly; when inhaling, the navel as well as the area below was projected outward strongly. The actions of exhaling and the inhaling were each conducted for 16 times per minute, and this practice was performed for 20 minutes each day. Exercise for controlling the diaphragm with a convex abdomen. The patients were asked to stand naturally. When inhaling, the navel as well as the area below was projected outward strongly and then the patients were asked to slowly and clearly make the ‘‘si’’ sound, whereas the convex state of the navel as well as the area below was remained. After a breath was exhausted, the patients would inhale with both the nose and the mouth and then begin to make another si sound. Each voicing of si was maintained for at least 30 seconds. This practice was performed for 20 minutes each day. Rapid breathing exercise. The patients were asked to stand naturally. The breath exercise with the convex and concave abdomen was executed rapidly, meaning that the actions of exhaling and inhaling were each conducted at least 50 times per minute, with each exercise lasting 1 minutes and performed five times a day. Relaxation exercise for the muscles at the base of the tongue and throat. The patients were asked to stand naturally, with the upper body leaning forward and both hands on the waist. The mouth was widely open, and the tongue was protruding out of the mouth. With the cervical axis, the head gently swung to drive the lashing of the tongue, such that the side of
Journal of Voice, Vol. 28, No. 3, 2014
the tongue could reach the left and right corners of the mouth. Each exercise lasted for 1 minute and was performed five times a day. (Note: Patients with severe cervical spondylosis were forbidden to perform this exercise.) Reciting vocal exercise. After the above four types of exercises were fully mastered, the actual exercise of vocal application was carried out. First, five-character Tang poetry was selected for slow reading to experience the feeling of the breath sounds. Then, seven-character Tang poetry, prose, and articles in newspapers were read with gradually accelerated speed that was close to or at the normal speed of standard communication speech. This practice was performed for 20 minutes each time. Testing methods The phonatory aerodynamic system model 6600 (KayPENTAX Corp, Lincoln Park, NJ) was used to detect the SGP, aerodynamic power (AP), MEA, and MPT for the above subjects. Before data acquisition, according to the correction system of the threshold value set by the instrument, the examinees were trained until they could comfortably execute the instructions. Measurement of the SGP and AP at the comfortable voicing state. An oral cavity catheter was inserted into the mouth of the examinee at approximately 2.5 cm, without the nozzle being blocked by the tongue or palate. The patient was asked to fasten the mask to the nose and mouth to avoid leakage and then the examinee was instructed to make a /pa-pa/ syllable using the comfortable sound, for five to seven successive times within a breath and one to two times per second. To ensure equal rhythm, participants were trained in each speaking task until they produced the syllable trains at the appropriate pace and were speaking at their comfortable loudness level. The first and last data points were abandoned, and the remaining data were automatically analyzed using the VOICING EFFICIENCY protocol. The values of the SGP and AP were recorded. Measurement of the MEA. The examinee was asked to fasten the mask to the nose and mouth to avoid leakage. Then, the examinee was instructed to make a /a/ syllable, with the sound intensity controlled at approximately 72 dB; each sound lasted for 5 seconds and was repeated three times, with 3–4 seconds of rest before each voicing. The stable data at the middle 5 seconds were automatically analyzed using the COMFORTABLE SUSTAINED PHONATION protocol. The values of MEA were recorded, and the final value was determined by the average of three measurements. Measurement of the MPT. The examinee was trained until they could comfortably execute the instructions, the instruction to take a deep breath, and a facial mask was used to cover the mouth and nose tightly without leakage. Subsequently, the subject was instructed to produce the vowel /a/ at a comfortable pitch and volume for as long as possible. The experiment was repeated three times. The results were analyzed using the MAXIMUM SUSTAINED PHONATION protocol. The
Fa-Ya Liang, et al
393.e9
Vocal Aerodynamic Changes in Female Patients With MTD
TABLE 1. The Aerodynamic Parameters of Female MTD Patients (Before and After 12-wk of Voice Training) and the Control Group Individuals Group
No.
Age (y)
SGP (cmH2O)
MPT (s)
MEA (L/S)
AP (W)
MTD before training MTD after 12-wk training Control group
21 21 20
34 (23; 41)* 34 (23; 41)* 31 (23; 39)
10.48 (8.45; 12.29)y,z 7.18 (5.42; 8.59)* 6.79 (4.93; 7.89)
12.51 (9.12; 16.91)y,z 21.62 (17.21; 24.96)* 23.67 (18.12; 26.92)
0.11 ± 0.04*,x 0.12 ± 0.03* 0.13 ± 0.03
0.14 ± 0.05y,z 0.09 ± 0.03* 0.08 ± 0.03
* Compared with control group, P > 0.05. y Compared with control group, P < 0.05. z Compared with MTD after 12-wk training, P < 0.05. x Compared with MTD after 12-wk training, P > 0.05.
longest time was collected, and the maximum value from three measurements was selected for further analysis. Statistical methods Data were analyzed with SPSS (version 18.0; Chicago, IL). Normal distribution variables were presented as mean ± standard deviation and nonnormal distribution variables were presented as median (P25; P75). The differences of normally distributed variables were determined by the t test and the nonnormally distributed data were determined by Mann– Whitney rank sum test. Values of P < 0.05 were considered significant. RESULTS The aerodynamic parameters of female MTD patients (before and after 12 weeks of voice training) and the control group individuals are listed in Table 1. Before voice training, the median SGP and mean AP was higher than that of the control group (SGP: 10.48 vs 6.79 cm H2O, Z ¼ 5.374, P < 0.01; AP: 0.14 vs 0.08 W, t ¼ 5.020, P < 0.01), whereas median MPT was shorter (12.51 vs 23.67 seconds, Z ¼ 5.295, P < 0.01), and these differences were statistically significant. Moreover, the mean MEA of MTD patients was less than that of the control group (0.11 vs 0.13 L/s, t ¼ 1.449, P ¼ 0.155), although the difference was not statistically significant. After 12 weeks of voice training, the median SGP and mean AP were decreased and the median MPT was increased compared with the measurements obtained before training, and these differences were statistically significant (SGP: 7.18 vs 10.48 cmH2O, Z ¼ 4.415, P < 0.01; AP: 0.08 vs 0.15W, t ¼ 4.029, P < 0.01; and MPT: 21.62 vs 12.51 seconds, Z ¼ 4.113, P < 0.01). In addition, the mean MEA of MTD patients was increased compared with the measurements obtained before training, although the difference was not statistically significant (0.12 vs 0.11 L/s, t ¼ 0.715, P ¼ 0.479). The differences of median SGP, mean AP, mean MEA, and median MPT between MTD after 12 weeks of training and control group were not statistically significant (SGP: 7.18 vs 6.79 cmH2O, Z ¼ 1.865, P ¼ 0.062; AP: 0.09 vs 0.08 W, t ¼ 0.899, P ¼ 0.374; MEA: 0.12 vs 0.13 L/s, t ¼ 1.339, P ¼ 0.188; and MPT: 21.62 vs 23.67 seconds, Z ¼ 1.930, P ¼ 0.054).
DISCUSSION The etiology of MTD is multifactorial but often includes dysphonia, which is caused by the misuse and abuse of the voice under certain predisposing factors. The clinical characteristics of MTD are also diverse, with the main symptoms including the following: a burning sensation in the throat; tight voice; laborious voicing; shallow breathing for sharp and high pitched sounds; an above-normal position of the larynx when voicing; tense muscles on the hyoid bone; the lack of organ disease in the vocal fold found by laryngoscopy examination; squeezing of the bilateral vocal edges when voicing; visible gap in the glottis area; excessive adduction of the plica vestibularis; extrusion of the throat; and sphincter-like change in the throat due to excessive squeezing.3,4,9 Because MTD patients present no organic disease in the vocal folds but their habits of voicing are incorrect, the treatment mainly consists of voice-based training supplemented with throat massage.6–8 The SGP refers to the lung pressure reaching the subglottic airway, which is one of the most common indicators in the study of aerodynamics10 and also the least disturbed of many aerodynamic indicators.11 In normal voice, the general SGP is only 5–8 cmH2O.12 The median value of SGP for the normal adults measured in this study was 6.55 cmH2O, which is consistent with the reported value. SGP may reflect the functional status of the throat and is related to the tension and the quality of the vocal fold. Our previous studies suggested that MTD patients have an excessively strong state of laryngeal vocal function and that their SGP is higher than that in normal controls (P < 0.01). The reason for this finding may be that tension in the laryngeal muscles of MTD patients leads to an increase in the quality and tension of the vocal folds, such that the vocal fold vibration is affected and the SGP needs to be increased to maintain the tension and vibration of the vocal fold. After 12 weeks of voice training, the SGP of the MTD patients was decreased, although it remained slightly higher than that of the normal control group, but this difference was not statistically significant (P > 0.05). This result suggested that voice training could reduce the tension of the laryngeal muscle and reduce the tension and quality of the vocal fold, such that the patients could maintain the vibration of the vocal fold through lower SGP. The MEA may reflect the closure status and the vocal intensity of the glottis. The examinees in this study were asked to
393.e10 maintain the sound intensity at approximately 72 dB to exclude the influence of sound intensity. After excluding this factor, the MEA was significantly correlated with the level of the glottis closure; if the level of the glottis closure decreased, the MEA was significantly increased, and vice versa. Kitajima13 reported that when the tension of the vocal fold increased (such as in spasmodic dysphonia), the MEA was decreased significantly. Because the majority of the MTD patients showed excessively strong contraction of the throat muscles, a high level of glottis closure, and increased vocal tension, the MEA was decreased. We also observed that the MEA of the MTD group was lower than that of the control group, although the difference was not statistically significant. The reason for this difference may be that the contractions of the cricoarytenoid muscle in some MTD patients were not synchronized between the front and back areas, such that they squeezed each other at the front area of the vocal fold and the gap in the glottis area could be observed under a laryngoscope. This incomplete glottis closure led to an abnormal increase in airflow rate. After the voice training, the excessively strong contraction of the laryngeal muscle in MTD patients was eased, the vocal tension was reduced, and the strength of the glottis closure was reduced; as a result, the MEA was higher than that before training and reached a level similar to the normal control group. The AP was obtained by the conversion of the SGP and the MEA. Our study showed that the AP of the MTD patients was higher than that of the normal control group, and this difference was statistically significant (P < 0.01). The occurrence of this phenomenon may be related to the method used to calculate AP. The SGP and MEA were both increased in patients with voice disorders, so the multiplication product of the two measurements was inevitably increased. Despite some MTD patients showing a decreased MEA, an increased result was still obtained when the result was multiplied with the SGP value. The increase in the AP suggests that the energy required for vocal sound is generally higher in MTD patients, that is, that speaking requires more effort. After 12 weeks of voice training, the tension of the laryngeal muscle in MTD patients was decreased, the vocal tension was reduced, and the SGP was significantly decreased, resulting in a decrease in AP. Altogether, these results indicate that MTD patients were able to speak with less effort following voice training. The MPT represents the longest duration of audible sound made by the examinee, and this aerodynamic indicator is associated with several factors including lung capacity, the degree of glottis closure, the breathing method, and breath control. Solomon et al14 proposed that the MPT is negatively correlated with the throat and airway resistance. The MPT of the MTD pa-
Journal of Voice, Vol. 28, No. 3, 2014
tients measured in this study was shorter than that of the control group, and this difference was statistically significant. The reason for this difference is related to the improper application of respiratory airflow and poor coordination when voicing in MTD patients. After voice training, the breathing habits of the MTD patients were re-established, and the respiratory system provided better support for the voicing process. As a result, the MPT was significantly improved and reached the level of the normal control subjects. In summary, voice training represents an effective treatment for MTD patients. Moreover, aerodynamic analysis can effectively evaluate the vocal functional status of MTD patients before and after training, which is beneficial for treatment efficacy evaluation. REFERENCES 1. Izadi F, Salehi A. Comparison between palpatory findings of the hyoid position and their acoustic, videostroboscopic, and perceptual attributes in patients with muscle tension dysphonia (with and without organic lesions). J Voice. 2013;27:78–83. 2. Morrison MD, Nichol H, Rammage LA. Diagnostic criteria in functional dysphonia. Laryngoscope. 1986;96:1–8. 3. Koufman JA, Blalock PD. Functional voice disorders. Otolaryngol Clin North Am. 1991;24:1059–1073. 4. Morrison MD, Rammage LA. Muscle misuse voice disorders: description and classification. Acta Otolaryngol. 1993;113:428–434. 5. Zheng YQ, Zhang BR, Su WY, Gong J, Yuan MQ, Ding YL, Rao SQ. Laryngeal aerodynamic analysis in assisting with the diagnosis of muscle tension dysphonia. J Voice. 2012;26:177–181. 6. Van Houtte E, Van Lierde K, Claeys S. Pathophysiology and treatment of muscle tension dysphonia: a review of the current knowledge. J Voice. 2011;25:202–207. 7. Mathieson L, Hirani SP, Epstein R, Baken RJ, Wood G, Rubin JS. Laryngeal manual therapy: a preliminary study to examine its treatment effects in the management of muscle tension dysphonia. J Voice. 2009;23: 353–366. 8. Van Lierde KM, De Bodt M, Dhaeseleer E, Wuyts F, Claeys S. The treatment of muscle tension dysphonia: a comparison of two treatment techniques by means of an objective multiparameter approach. J Voice. 2010; 24:294–301. 9. Morrison MD, Rammage LA, Belisle GM, Pullan CB, Nichol H. Muscular tension dysphonia. J Otolaryngol. 1983;12:302–306. 10. Bard MC, Slavit DH, McCaffrey TV, Lipton RJ. Noninvasive technique for estimating subglottic pressure and laryngeal efficiency. Ann Otol Rhinol Laryngol. 1992;101:578–582. 11. Goozee JV, Murdoch BE, Theodoros DG, Thompson EC. The effects of age and gender on laryngeal aerodynamics. Int J Lang Commun Disord. 1998; 33:221–238. 12. Baken RJ, Orlikoff RF. Clinical Measurement of Speech and Voice. Independence, KY: Cengage Learning; 2000:297–331. 13. Kitajima K. Airflow study of pathologic larynges using a hot wire flowmeter. Ann Otol Rhinol Laryngol. 1985;94(2 pt 1):195–197. 14. Solomon NP, Garlitz SJ, Milbrath RL. Respiratory and laryngeal contributions to maximum phonation duration. J Voice. 2000;14:331–340.
