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Commun Sci Disord > Volume 18(2); 2013 > Article
성악가를 위한 한국어 음성장애지수(K-SVHI)의 적용 연구

초록

Objectives:

The purpose of this study was to generate a Korean version of the Singing Voice Handicap Index (K-SVHI) and to test whether application of the K-SVHI would be plausible for patients with voice disorders.

Methods:

Subjects who participated in the study were 130 vocalists, including 90 normal and 40 dysphonic vocalists. The group of normal vocalists consisted of 30 students majoring in vocal music, 30 members of the chorus and 30 performing musicians. The Korean version of SVHI was translated into Korean from the English version. Three different types of rating tools were used to document the subject’s perception of the handicap of Korean vocalists: the first item of Iowa Patient’s Voice Index (IPVI), VHI and K-SVHI. Internal consistency reliability, test-retest reliability and concurrent validity were assessed as well as group differences.

Results:

The results of this study are summarized as follows. 1) There was a high internal consistency between items of K-SVHI. Test-retest reliability was extremely high. With regards to the concurrent validity, Spearman correlation between the K-SVHI and IPVI’s first item was high in the dysphonic vocalists group. 2) Dysphonic vocalists had higher K-SVHI scores compared to normal vocalists. 3) Three normal vocalist groups showed significant differences from each other when analyzed with the ANOVA. Students majoring in vocal music received significantly higher scores than members of the chorus, and members of the chorus had higher scores than the performing musicians.

Conclusion:

The K-SVHI seems to be a useful psychometric instrument for assessing the voice handicap of Korean vocalists with voice problems.

The traditional clinical assessment of voice disorders have been made based on objective acoustic/aerodynamic measures and subjective auditory-perceptual judgments of listeners. However, in order to measure the outcome of the treatment adequately, recent studies have additionally suggested clinical measurements of the impact of voice problems on the daily lives of individual patients as well as the perceived level of handicap resulting from voice problems (Kim et al., 2007).
The Voice Handicap Index (VHI) is a widely used instrument in some countries, including Korea, for scaling the severity of the perceived handicap felt by patients with voice problems (Yoon, Kim, Sohn, & Choi, 2008). VHI has been used for the clinical purpose to examine the treatment outcome by comparing patients’ perception of handicap before and after treatment. Post-treatment change in the VHI scores reflects voice improvement which the patient has experienced in daily life through treatment (Colton et al., 2011). However, VHI has limitations in assessing singing voice problems because none of the 30 items are related to the singing voice.
Compared to non-singers, singers are exposed to a higher risk for voice problems and are more sensitive to their voice problems. In particular, professional singers have a higher level of perceived voice problems than those who are retired and are engaged in few social activities (Phyland, Oates, & Greenwood, 1999). Further, professional singers belonging to different groups feel a different level of stress from their voice problems. For this reason, in this study, we subdivided subjects into the following three groups: chorus, singing students and professional performers.
The Singing Voice Handicap Index (SVHI) is a newly developed tool for measuring voice handicap associated with singing voice problems (Cohen et al., 2007). SVHI is comprised of 36 questions. The patient completes the questionnaire by using a 5-point rating scale to indicate his/her response. The SVHI is an ordinal scale, each question of which is scored from 0 (never) to 4 (always); the total score ranges between a minimum of 0 and a maximum of 144. A higher score indicates that the patient’s perception of disability caused by the voice problem is more severe. Recent studies reported that the SVHI is more reliable, valid and more sensitive to the VHI in detecting the changes in singers after voice treatment (Cohen Statham, Rosen, & Zullo, 2009). Therefore, it is a valuable instrument for measuring the handicap that results from singing voice disorders (Cohen et al., 2007).
The aims of this study were 1) to make a K-SVHI questionnaire by translating SVHI into Korean, and evaluate the Korean version of SVHI by assessing its validity and reliability, and 2) to assess the subjective perception and attitude toward voice disorders in Korean dysphonic vocalists by using the K-SVHI.

METHODS

Subjects

Subjects in the study included 130 vocalists, including 90 normal and 40 dysphonic vocalists. Ninety normal vocalists were divided into three groups of students majoring in vocal music, members of the chorus and performing musicians. Forty adult males and females over 20 years of age, who were diagnosed as dysphonic vocalists after receiving over five years of vocal training, were selected as experimental subjects. Dysphonic vocalists had not received medical or surgical treatment for dysphonia, and they did not carry any mental or physical disorders. Forty dysphonic vocalists consisted of 13 vocalists with vocal nodule, 5 with vocal cyst, 14 with muscle tension dysphonia, 4 with vocal polyp, 2 with spasmodic dysphonia, one with Reinke’s edema, and one with laryngitis.
Ninety adult normal vocalists over 20 years of age with over five years of vocal training and no medical history of voice disorder were selected as experimental subjects. Normal vocalists did not particularly feel any voice problems, and have not visited the ENT clinic specializing on voice treatment in the last three months. Yoon (2007) sorted the normal group by using the first item of the Iowa Patient’s Voice Index (IPVI). IPVI was developed by Verdolini and colleagues at the University of Iowa as a means of concisely documenting patients’ perceptions of their own voice quality, vocal effort and impact of dysphonia on their lives (Karnell et al., 2007). The first item of the IPVI was administered to patients in order to rate voice quality on an equal-appearing interval scale (e.g., 0, normal or no impact; and 6, severe or great impact); moreover, Yoon (2007) excluded participants from the normal group if his/her mark was higher than 2.
However, we believed that it is inappropriate to use the first question of the IPVI solely as a screening test for professional singers, because the test is too simple for them. In order to complement this point, we used VHI-30, which is the most representative psychometric assessment along with the IPVI’s first question.
We excluded participants from the normal group if his/her mark was higher than 2 in any question item of VHI-30 because we thought it conveyed the risk factors of voice disorders. Cohen et al. (2007) also assumed that subjects not feeling voice problems in their everyday lives made a negative response at 0, meaning “never,” and at 1, meaning “almost never;” further, subjects recognizing the frequency of voice problems and severity of voice problems made a positive response at 2, implying “sometimes,” and at 4, implying “always,” in the VHI-30 questionnaire items.
The group of normal vocalists consisted of 30 students majoring in vocal music, 30 chorus members and 30 performing musicians. In a study by Phyland et al. (1999), singers were required to have sung more than 2 hours per month on average during the previous year; however, our study targets normal vocalists having received vocal training for over five years. Due to the fact that performing musicians usually practice two to three months for their stage performances, the target group for this study included performers participating in performances at least four times a year.
Three groups of subjects were selected for the following reasons.
In the case of chorus and professional performers, the authors thought that despite the fact that they all made an income by singing, the degree of stress between chorus and professional performers when singing would be different. Because singing students do not have a regular full-time job but make extra income by singing, we thought that they portrayed different aspects compared to chorus and performer groups.

Experimental Procedure and Data Analysis

Development of the K-SVHI for vocalists and data collection

Three bilingual users who speak Korean and English at the level of native speakers translated the SVHI. While two of them are specialists working at the voice clinic of otolaryngology, the other user is not a specialist. In addition, the concept of content validity was used to increase the accuracy of measurement. Three speech pathologists with experiences in voice disorder evaluation and treatment for at least five years and three vocalists who studied vocal music at universities and have over 20 years of experience in performance and vocal lessons were selected to perform content validity. Speech pathologists and three vocalists assisted in the translation of SVHI in order to help vocalists understand as well as to check the terminology. These three high profile specialists collaborated with one another for these reasons. K-SVHI is attached in Appendix 1.
The Korean version of the SVHI were reviewed and modified by three bilingual users, three speech pathologists and three vocalists.
Three different types of questionnaires were administered to all subjects in the order of IPVI’s first question, VHI and K-SVHI. In this study, the first item of IPVI was used to examine the overall recognition degree of voice problems by dysphonic vocalists. After we distributed copies of surveys to subjects and briefly explaining the method of scoring, subjects were allowed to fill out the survey.

Data & statistical analysis

Data analysis was statistically conducted using the SPSS ver. 12.0 (SPSS Inc., Chicago, IL, USA). Two independent samples t-tests were used to compare the distinctiveness between normal vocalists and dysphonic vocalists. Analysis of variance (ANOVA) was used to compare the three groups of normal vocalists-students majoring in vocal music, members of the chorus and performing musicians. Test-retest reliability was tested with Pearson correlation, and Spearman correlation coefficients calculated the validity of K-SVHI and the existing tests as well as the official validity. Approximately 10% of the subjects were asked to re-test in order to measure the reliability of the test tool. K-SVHI was completed at the initial presentation, and a second copy was mailed one week after the initial participants’ visit. This timing was chosen so that the patients’ vocal health state would not have changed and they would not remember their initial answers. As a result of conducting a retest of K-SVHI on 10% of the subjects, including 9 normal vocalists and 4 dysphonic vocalists, the degree of congruence within subjects in the Pearson correlation analysis was extremely high (r=.988, p<.01).

RESULTS

Reliability and Validity of K-SVHI

The internal consistency for the K-SVHI, as measured by Cronbach’s α, was 0.911 for the normal vocalist group and 0.951 for the dysphonic vocalist group. The item-total score correlations calculated for all 36 items ranged from 0.18 to 0.83. Generally, higher item discrimination can be more reliable. According to Ebel’s guidelines on the evaluation of item discrimination, more than 0.40 is ‘good’, 0.30 to 0.39 is ‘okay’, 0.20 to 0.29 is ‘low’, and 0.10 to 0.19 is ‘poor’ (Sung, 2004).
Concurrent validity was evaluated by comparing the K-SVHI scores to VHI and also by comparing the first item of IPVI using Spearman correlation analysis. Analysis on the validity of K-SVHI total score and the first item of IPVI for each of normal and dysphonic vocalist groups showed a relatively high correlation (normal vocalists: r=.675, p<.01; dysphonic vocalists: r=.783, p<.01). Analysis on the validity of the total score of K-SVHI and VHI for each normal and dysphonic vocalist groups showed a significant correlation (normal vocalist: r=.543, p<.01; dysphonic vocalist: r=.452, p<.01).

Comparison of K-SVHI between Dysphonic and Normal Vocalist Group

Dysphonic vocalists had higher K-SVHI scores than normal vocalists (t=-12.395, p<.05). The average K-SVHI score of the normal vocalist group was 19.84 (SD=12.84), whereas the average K-SVHI of the dysphonic vocalist group was 70.63 (SD=33.90). These results are presented in Figure 1.
In the dysphonic vocalist group, comparisons of total K-SVHI scores among diseases were shown in Figure 2. Reinke’s edema of organic voice disorders and spasmodic dysphonia of neurological voice disorders are shown to have the highest scores. Of the functional voice disorders, vocal cyst, with a score of 103.6, is shown to have a high score compared with vocal nodule or vocal polyp. However, muscle tension dysphonia, which is in the same category of functional voice disorders, showed a relatively low score. Further, laryngitis of inflammatory voice disorders showed a low score.

Comparison of K-SVHI among Normal Vocalist Groups

Analysis of variance showed significant differences in K-SVHI scores among the three normal vocalist groups; students majoring in vocal music, members of the chorus and performing musicians (p<.05). The average K-SVHI was 30.17 (SD=11.02) for university students majoring in vocal music, 19.93 (SD=10.47) for members of the chorus and 9.43 (SD=7.23) for performers. According to the Scheffe F analysis, students majoring in vocal music attained significantly higher scores compared to members of the chorus, and the members of the chorus had higher scored compared to performing musicians (p<.001). These results are presented in Figure 3.

CONCLUSION

The SVHI translated in Korean has been proved to have good reliability and validity. For each group, the normal vocalist group and the dysphonic vocalist group showed 0.911 and 0.951 as Cronbach’s α value. It indicates that there was a high internal consistency between items of K-SVHI; moreover, it verified that K-SVHI is composed of relatively uniform items. The high confidence level of test-retest reliability (r=.99) explained that subjects evaluated their voice problems coherently.
The normal vocalist group received significantly lower scores than did the dysphonic vocalist group. The K-SVHI discriminated between vocalists with vocal dysfunction and normal vocalists. This finding further supports its validity. With regard to the concurrent validity Spearman correlation between the K-SVHI and IPVI’s first item was high (dysphonic vocalists group: r=.783, p< .01; normal vocalists group: r=.675, p<.01).
In this study, K-SVHI showed a higher correlation with IPVI’s first item than that of the VHI. The VHI has not been specifically validated among singers and the individual question may not be sensitive enough to detect changes among singers with voice complaints (Hogikyan & Sethuraman, 1999; Jacobson et al., 1997; Murry, Zschommler, & Prokop, 2009; Rosen Lee, Osborne, Zullo, & Murry, 2004). On the other hand, the first item of IPVI is to examine the overall recognition degree of voice problems. It could be surmised that IPVI’s first item was more sensitive to the voice problems of dysphonic vocalist group than to the VHI for these reasons. However, there were limitations in obtaining the concurrent validity by using a voice related psychometric evaluation of the existing instrument because there is no tool focused on the singing voice.
Dysphonic vocalists in this study had higher K-SVHI scores than normal vocalists. In the previous study (Cohen et al., 2007), compared to the 112 singing patients, the control group of singers had lower SVHI scores; a median of 22 vs. a median of 61 (p≤.001, rank sum test). Also, the patients’ SVHI scores were twice the control group’s SVHI scores regardless of professional, income or classical singing status (p≤.001, rank sum test). The average K-SVHI score of the normal vocalist group was 19.84 (SD=12.84) while the average K-SVHI score of the dysphonic vocalist group was 70.63 (SD=33.90). Dysphonic vocalist groups showed three times higher scores than the normal vocalist groups. This result suggests that K-SVHI may be used as a tool for judging whether a vocalist has his/her own voice problems.
The three vocalist groups.students majoring in vocal music, members of the chorus and performing musicians.showed significant differences from each other. The students majoring in vocal music received significantly higher scores than members of the chorus, and members of the chorus had higher scores than the performing musicians. Students majoring in vocal music are thought to have shown the highest scores because they have not yet settled their voices completely and are in a learning/training period in which they learn to be a professional performer (Sim, 2013). In the case of chorus members, the tendency to place importance on harmony with other people’s sound results in the difficulty of making desirable sounds (Gil, 2009). Lastly, because most performing musicians are equipped with a certain level of singing ability, they are confident about their singing and therefore are capable of making great sounds by resolving any unsatisfactory parts of their voice through many experiences and trials (Caruso & Tetrazzini, 1995). For example, singers through the trial and error experience would learn the appropriate location of the tongue and the larynx; thus, they can make the most effective sound (Caruso & Tetrazzini, 1995). However, there is a limit in generalizing the results of this study due to the small sample size of each group. In order to ensure homogeneity of the group, the same clinical diagnosis of the dysphonic group or similar severity will be needed for future research. If so, the study will be able to obtain more validity. Therefore, it is necessary to include a large number of groups in future studies.
In conclusion, the K-SVHI is a reliable and valid instrument for assessing Korean singer’s perceived handicap of voice disorders. Consequently, the K-SVHI can aid in the assessment of dysphonic singers. However, there are limitations in generalizing the results for all vocal musicians as well as applying them to groups of singers with different styles and musical genres because this study only observed a small number of participants, all of whom are classical singers.

Notes

CONFLICT OF INTEREST
No potential conflict of interest relevant to this article was reported.

figures

Figure 1.
Comparison of Korean version of the Singing Voice Handicap Index (K-SVHI) score between normal vocalist group and dysphonic vocalist group.
csd-18-2-6-f1.gif
Figure 2.
Comparison of total Korean version of the Singing Voice Handicap Index (K-SVHI) score according to diagnosis group.
csd-18-2-6-f2.gif
Figure 3.
Comparison of Korean version of the Singing Voice Handicap Index (K-SVHI) scores of three vocalists groups.
csd-18-2-6-f3.gif

REFERENCES

Caruso, E., & Tetrazzini, L. (1995). Caruso and Tetrazzini on the art of singing. Seoul: Chungwoo.

Cohen, SM., Jacobson, BH., Garrett, CG., Noordzij, JP., Stewart, MG., Attia, A., Ossoff, RH., & Cleveland, TF. (2007). Creation and validation of the Singing Voice Handicap Index. Annals of Otology, Rhinology & Laryngology. 116, 402–406.
pmid
Cohen, SM., Statham, M., Rosen, CA., & Zullo, T. (2009). Development and validation of the singing voice handicap-10. Laryngoscope . 119, 1864-–1869.
crossref pmid
Colton, RH., Casper, JK., & Hirano, M. (2011). Understanding voice problems: a physiological perspective for diagnosis and treatment (4th ed.). Philadelphia, PA: Lippincott Williams & Wilkins.

Gil, HJ. (2009). Influencing model for leaders of choirs and chorus (Master’s thesis). Kyung Hee University, Seoul, Korea.

Hogikyan, ND., & Sethuraman, G. (1999). Validation of an instrument to measure voice-related quality of life (V-RQOL). Journal of Voice. 13, 557–569.
crossref pmid
Jacobson, BH., Johnson, A., Grywalski, C., Silbergleit, A., Jacobson, G., & Benninger, MS. (1997). The Voice Handicap Index (VHI): development and validation. American Journal of Speech-Language Pathology. 6, 66–70.

Karnell, MP., Melton, SD., Childes, JM., Coleman, TC., Dailey, SA., & Hoffman, HT. (2007). Reliability clinician based (GRBAS and CAPE-V) and patient-based (V-RQOL and IPVI) documentation of voice disorders. Journal of Voice. 21, 576–590.
crossref pmid
Kim, JO., Lim, SE., Park, SY., Choi, SH., Choi, JA., & Choi, HS. (2007). Validity and reliability of Korean-version of voice handicap index and voice- related quality of life. Korean Journal of Speech Sciences. 14, 111–125.

Murry, T., Zschommler, A., & Prokop, J. (2009). Voice handicap in singers. Journal of Voice. 23, 376–379.
crossref pmid
Phyland, DJ., Oates, J., & Greenwood, KM. (1999). Self-reported voice problems among three groups of professional singers. Journal of Voice. 13, 602–611.
crossref pmid
Rosen, CA., Lee, AS., Osborne, J., Zullo, T., & Murry, T. (2004). Development and validation of the Voice Handicap Index-10. Laryngoscope. 114, 1549–1556.
crossref pmid
Sim, SY. (2013). A correlation between undergraduate music majors’ self-efficacy and confidence in performance. (Master’s thesis). Ewha Womans University, Seoul, Korea.

Seong, TJ. (2004). Test item development: evaluation and practice (2nd ed.). Seoul: Hakjisa.

Yoon, YS. (2007). Korean-Voice Handicap Index (K-VHI): validation of an original version and development of new version (Doctoral dissertation). Yonsei University, Seoul, Korea.

Yoon, YS., Kim, HH., Sohn, YI., & Choi, HS. (2008). Validation of the Korean Voice Handicap Index (K-VHI) and the clinical usefulness of Korean VHI-10. Korean Journal of Communication Disorders. 13, 216–241.

Appendices

Appendix 1.

Korean version of the Singing Voice Handicap Index (K-SVHI)-36

csd-18-2-8-a1.gif
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