International Journal of Pediatric Otorhinolaryngology 78 (2014) 312–316

Contents lists available at ScienceDirect

International Journal of Pediatric Otorhinolaryngology journal homepage: www.elsevier.com/locate/ijporl

Perceptual and acoustic parameters of vocal nodules in children Andre´a Cristina Joia Gramuglia a, Elaine L.M. Tavares a, Se´rgio Augusto Rodrigues b, Regina H.G. Martins a,* a b

Department of Ophthalmology, Otolaryngology and Head and Neck Surgery, Botucatu Medical School, UNESP – Univ Estadual Paulista, Brazil Department of Biostatistics, Botucatu Biosciences Institute, UNESP – Univ Estadual Paulista, Brazil

A R T I C L E I N F O

A B S T R A C T

Article history: Received 6 September 2013 Received in revised form 23 October 2013 Accepted 26 November 2013 Available online 4 December 2013

Vocal nodules constitute the major cause of dysphonia during childhood. Auditory-perceptual and acoustic vocal analyses have been used to differentiate vocal nodules from normal voice in children. Purpose: To study the value of auditory-perceptual and acoustic vocal analyses in assessments of children with nodules. Design: Diagnostic test study. Patients and interventions: A comparative study was carried out including 100 children with videolaryngoscopic diagnosis of vocal nodules (nodule group-NG); and 100 children without vocal symptoms and with normal videolaryngoscopic exams (control group-CG). The age range of both groups was between 4 and 11 years. All children underwent auditory-perceptual vocal analyses (GRBASI scale); maximum phonation time and s/z ratio were calculated, and acoustic vocal analysis (MDVP software) were carried out. Results: There was no difference in the values of maximum phonation time and s/z ratio between groups. Auditory-perceptual analysis indicated greater compromising of voice parameters for NG, compared to CG: G (79 versus 24), R (53 versus 3), B (67 versus 23) and S (35 versus 1). The values of acoustic parameters jitter, PPQ, shimmer, APQ, NHR and SPI were higher for NG for CG. The parameter f0 did not differ between groups. Conclusion: Compromising of auditory-perceptual (G, R, B and S) and acoustic vocal parameters (jitter, PPQ, shimmer, APQ, NHR and SPI) was greater for children with nodules than for those of the control group, which makes them important methods for assessing child dysphonia. ß 2013 Elsevier Ireland Ltd. All rights reserved.

Keywords: Child Dysphonia Nodules Hoarseness Auditory-perceptual vocal analysis Acoustic vocal analysis.

1. Introduction Vocal nodules are the major causes of dysphonia during childhood and have been diagnosed in 40–60% videolaryngoscopic exams of dysphonic children. They prevail among boys until adolescence, peaking between 5 and 10 years of age [1–3]. Vocal abuse and incorrect use of the voice are the main predisposing factors [4,5]. Hyperactivity, impulsiveness and anxiety are psychoemotional features common to children with nodules [6]. Nodule formation starts with the traumatic collision between vocal folds, leading to damages to the epithelium and the lamina propria. Laryngeal hypercontraction causes increased pressure of capillaries of the lamina propria, which reaches values higher than 20 cm H2O, resulting in transudate, inflammatory cell influx and subepithelial edema [7]. The basement membrane and the

* Corresponding author at: Departamento de Oftalmologia, Otorrinolaringologia e Cirurgia de Cabec¸a e Pescoc¸o, Faculdade de Medicina da Universidade Estadual Paulista (UNESP), Distrito de Rubia˜o Junior, Botucatu, CEP 18618-970, Sa˜o Paulo, Brazil. Tel.: +55 14 38801523; fax: +55 14 38801523. E-mail address: [email protected] (Regina H.G. Martins). 0165-5876/$ – see front matter ß 2013 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ijporl.2013.11.032

epithelium concomitantly thicken, while the fibronectin and the collagen in the lamina propria increase, making the lesion more rigid and fibrotic [8,9]. Vocal nodules are diagnosed by means of videolaryngoscopic exams, which are easily performed for adults (Fig. 1). For children, however, these exams are impaired due to their lack of collaboration and immaturity. Although the videolaryngoscopic exam is essential for the diagnosis of vocal nodules, the acoustic and auditoryperceptual vocal analyses have been employed as complementary assessment methods. Some authors have highlighted the importance of assessing the psychoacoustic parameters of GRBASI scale, i.e., roughness, strain and breathiness for bearers of vocal nodules [10,11]. Others have questioned the importance of breathiness since this parameter is naturally observed to a certain degree in the voice of children during phonation due to posterior glottic incompetence [12]. Such divergent opinions indicate the importance of using quantitative methods in vocal assessments, reducing thus the subjectivity degree. For this purpose, acoustic vocal analyses have shown valuable assessment tools. The use of acoustic analyses has led to high jitter, shimmer and NHR values and lower f0 values for the voices of children with

A.C.J. Gramuglia et al. / International Journal of Pediatric Otorhinolaryngology 78 (2014) 312–316

vocal nodules, differentiating them from normal voices [10,13]. Vocal analyses have also been employed in the follow-up of vocal rehabilitation treatment, for both adults and children [14]. There are some studies in the literature addressing auditoryperceptual and acoustic measures in children bearing vocal nodules; however, there is lack of careful and comprehensive investigation corroborating the results of those authors. 2. Objective To study the perceptual and acoustic vocal parameters of vocal nodules in children. 3. Casuistry and interventions The present study included 100 children aged from 4 to 11 years, with videolaryngoscopic diagnosis of vocal nodules (nodule group – NG), attended at the Voice Disorders Outpatient Clinics of the Discipline of Otolaryngology of Botucatu Medical School (UNESP) between 2011 and 2013. The results of perceptual auditory and vocal analysis were compared to those of a control group (CG), composed of 100 children without vocal symptoms and with normal videolaryngoscopic exams. Those control children had previously participated in an extensive epidemiologic study conducted by the same group of investigators [3]. They were attended at the same clinics and belonged to the same corresponding age range. Excluded were children with: hearing impairment; genetic syndrome and/or associated craniofacial malformation; history of prolonged intubation or cervical trauma; neurological diseases with compromised voice and speech; and dubious diagnosis of vocal nodules, or children that did not allow endoscopic assessment or acoustic or perceptual vocal analysis. The parents of all children filled out a free and informed consent authorizing the exams, as well as a questionnaire of voice evaluation. Then, the children were subjected to videolaryngoscopy conducted by an otolaryngologist, who used the conjugate image capture system (multifunctional videosystem type XE-50, Eco V 50 W, Carl-Zeiss, Germany), flexible nasofibrolaryngoscope (3.3 mm; Ollimpus, Japan) or rigid laryngeal telescope (8 mm diameter, 708, Asap, Germany) and conjugated microcamera (Asap, Germany). Auditory-perceptual vocal assessments (maximum phonation time and GRBASI scale) were conducted by speech therapists who were experts in voice. The assessments were made during spontaneous speech, based on the counting of numbers from one to ten and sustained vowel emission /a/. Results were interpreted by two professionals who were experts in voice and their judgment should be similar. When there was no concordance, the records were analyzed by a third professional. For computerized acoustic vocal assessments, the software Multi Dimensional Voice Program (MDVP, model 5105, MultiSpeech 3700, Kay Elemetrics Corporation, Germany) was employed; the definitive measurements were preceded by the training of children for understanding the test, and vocal samples were obtained during the sustained emission of vowel /a/, only

313

removing 0.5 initial and final seconds and keeping comfortable height and frequency levels. The analyzed vocal parameters were: Fundamental Frequency (f0), Jitter Percentage (%), Pich Perturbation Quotient (PPQ), Shimmer Percentage (%), Amplitude Perturbation Quotient (APQ), Noise Harmonic Ratio (NHR), Soft Phonation Index (SPI). The research project was approved by the Human Research Ethics Committee of Botucatu Medical School (UNESP, protocol CEP 3996-2011). Statistical analysis for comparing the quantitative variables relative to both groups was done by using paired t-test when the variable had adherence to normal probability distribution; for the study between groups of the variables of GRBASI scale, Goodman test [15,16] was complemented with multiple comparisons between and within binomial or multinomial populations, considering 5% significance level. 4. Results 4.1. Sex and age range Groups were homogeneously distributed according to age range and sex (Table 1). 4.2. Maximum phonation time The maximum phonation time for phonemes /a/ and /z/ was discreetly shorter for children of the nodule group (Table 2). 4.3. Auditory-perceptual vocal analysis – GRBASI scale Auditory-perceptual assessments identified some changes in the voices of children with nodules, differentiating them from normal voices. Most NG children had degree 1 of vocal change (G; n-63), which was recorded for only 24 children with normal voices. Degree 1 of roughness (R) was indentified for 42 NG children and for only 3 CG children. The degree of breathiness (B) for both groups was also significant and degree 1 of this parameter was identified for 54 NG children and 23 CG children. In addition, for 33 NG children, no degree of breathiness in the vocal emission was recorded. Strain (S) was slightly altered for 33 NG children and for only one control child. Asthenia (A) and instability (I) were not relevant between groups (Table 3). 4.4. Acoustic vocal analysis f0 values did not differ between groups, but the values of all remaining acoustic parameters, i.e., jitter, PPQ, shimmer, APQ, NHR and SPI, were higher for NG children, compared to the control children (Table 4). 5. Discussion The larynx of children undergoes a series of changes from birth to adulthood, and its growth is not only dimensional. The

Table 1 Distribution of children according to sex and age range. Age range (years)

Nodule group

Control group

Male N (%)

Female N (%)

Male N (%)

Female N (%)

4–6 7–9 10–11

9 (15.25) 27 (45.76) 23 (38.99)

6 (14.63) 18 (43.90) 17 (41.47)

9 (15.25) 27 (45.76) 23 (38.98)

6 (14.63) 18 (43.90) 17 (41.47)

Total

59 (100.00)

41 (100.00)

59 (100.00)

41 (100.00)

8.87  2.44 1.01  0.17 8.59  1.58 8.16  2.11

7.67  2.35

8.02  2.28

(mean and standard deviation).

8.07  3.01

5.22  1.48

0.99  0.16

7.34*  2.01

9.73  1.97

10.04  2.21

0.98  0.09

8.62*  2.15

9.52  1.93

9.91  2.23

0.97  0.12

9.83  2.42

8.71  2.22

8.36  2.36 0.99  0.21 8.22  2.69

/z/

5.50*  1.58

/s/

0.98  0.15

7.91  2.72

7.33*  1.78

7.33*  2.11

1.02  0.16

6.57  1.95

7.81  1.82

8.15  1.97

0.97  0.14

8.06  2.26

8.22  1.80

/a/ s/z

0.97  0.15 5.33  1.63 5.00  1.10 5.39  1.36

/z/ /s/ /a/ s/z

0.92  0.22 5.44  2.30

/z/ /s/

4.78  1.79 4.92  1.50

/a/ s/z

0.98  0.17 5.00*  1.10

/z/ /a/

4.75  1.26

/s/

N

s/z

5.28  1.39

N

0.98  0.23

N

Male

Fig. 1. Bilateral vocal nodules (arrows).

4–6 *p < 0.05 7–9 *p < 0.05 10–11 *p < 0.05 Paired t–test

N

Female Control group (CG)

Male Female

Nodule group (NG) Age range

Table 2 Mean and standard deviation of maximum phonation time (MPT) for phonemes /s/, /z/, /a/ and calculation of the s/z ratio between groups, according to sex and age range (years).

6.58  3.20

A.C.J. Gramuglia et al. / International Journal of Pediatric Otorhinolaryngology 78 (2014) 312–316

314

intertwined organization of collagen and elastic fibers increasingly differs among superficial, intermediary and deep layers of the lamina propria; in the adult, the layout of elastic fibers is more superficial, while collagen fibers are in the deeper layers [17]. A large number of laryngeal changes are influenced by sexual hormones, especially the growth of the larynx cartilaginous skeleton and the vocal folds, as well as the angulation of the laminae of thyroid cartilage. Thus, the vocal characteristics of children, from the birth to adulthood, constitute a dynamic and continuous process, which is more evident during the voice changing period [18,19]. Therefore, whenever possible, in comparative studies, children should be allocated to homogeneous subgroups paired according to age ranges and sexes, as in the present study. Vocal nodules are the most frequent laryngeal lesions of the childhood and are directly related to vocal overuse, constituting common phonation patterns among children. The diagnosis of nodules is made with a flexible nasofibroscope or a rigid telescope. Although they are painless and rapid, many children do not collaborate, not allowing the accomplishment of these exams. In these cases, when the dysphonia degree is very significant or when symptoms are followed by dyspnea, direct laryngoscopic test under sedation is recommended in order to rule out more severe laryngeal lesions like congenital malformations, tumors, vocal fold paralysis and papillomatosis. In most cases, however, the symptoms of dyspnea are sporadic or do not exist, while dysphonia has a direct relationship with vocal abuse, indicating the main diagnosis, which is vocal nodule [5]. Some auditory-perceptual and acoustic vocal parameters have been capable of differentiating the voices of children with nodules from normal voices. For some authors, the maximum phonation time (MPT) is shortened in patients with vocal nodules since they depend especially on the coordination of pneumophonoarticulation and perfect glottal closure, which are compromised in most cases [20,21]. These results were also obtained in the present study. For children, the MPT increases with age and, in general, follows the corresponding age range [3,20,21]. As shown in Table 3, the results of auditory-perceptual vocal analyses indicated that most parameters had a greater change for children with nodules, compared to controls, respectively: G (79 versus 24), R (53 versus 3), B (67 versus 23) and S (35 versus 1). These data emphasize the importance of such parameters in perceptual analyses of the voices of children with nodules. According to Colton & Casper [22], the presence of vocal nodules and double closure provides the voice with some psychoacoustic characteristics, especially the parameters roughness and breathiness. Corroborating the present results, Oliveira et al. [11], in a study including 70 children aged between six and 10 years, noted

A.C.J. Gramuglia et al. / International Journal of Pediatric Otorhinolaryngology 78 (2014) 312–316

315

Table 3 Auditory-perceptual vocal analysis (GRBASI scale) between groups. Auditory-perceptual parameters

Group

Intensity degree 0

1

2

3

G

NG CG

21aA 76bC

63bB 24aB

16bA 0aA

0aA 0aA

p < 0.05

p < 0.05

p < 0.05

p > 0.05

R

NG CG

47aB 97bB

42bB 3aA

11bA 0aA

0aA 0aA

p < 0.05

p < 0.05

p < 0.05

p > 0.05

B

NG CG

33aB 77bC

54bB 23aB

13bA 0aA

0aA 0aA

p < 0.05

p < 0.05

p < 0.05

p > 0.05

A

NG CG

0aA 0aA

0aA 0aA

0aA 0aA

0aA 0aA

p > 0.05

p > 0.05

p > 0.05

p > 0.05

S

NG CG

65aC 99bB

33bB 1aA

2aA 0aA

0aA 0aA

p < 0.05

p < 0.05

p > 0.05

p > 0.05

I

aB

NG CG

aA

aA

98 99aB

2 1aA

0 0aA

0aA 0aA

p > 0.05

p > 0.05

p > 0.05

p > 0.05

p < 0.05 p < 0.05

p < 0.05 p < 0.05

p < 0.05 p < 0.05

p > 0.05 p > 0.05

p < 0.05 p < 0.05

p < 0.05 p < 0.05

Two frequencies followed by the same small letter do not differ concerning to the respective age groups (lines), fixing the gender (p > 0.05). Two frequencies followed by the same capital letter do not differ concerning to the genders (columns), fixing the age group (p > 0.05). OBS: Goodman Test.

Table 4 Mean and standard derivation of acoustic vocal parameters between groups according to sex and age range (years). *p < 0.001 – Bonferroni test. Acoustic parameters and range age (years)

Group Nodule group

Control group

Media (Desvio Padra˜o)

Media (Desvio Padra˜o)

Male

Female

Male

Female

F0 p 0.144

4–6 7–9 10–11

264.8  30.81 250.7  25.18 227.0  25.91

270.2  41.85 242.7  20.90 232.8  19.11

267.4  26.76 247.3  22.86 231.0  20.05

252.4  26.34 262.6  37.28 249.9  20.59

%jitter p < 0.001

4–6 7–9 10–11

1.68*  1.00 1.90*  1.08 2.10*  1.50

1.51*  0.66 1.45*  1.07 2.03*  0.99

0.61  0.32 0.98  0.48 0.94  0.54

0.65  0.44 0.89  0.62 0.93  0.76

PPQ p < 0.001

4–6 7–9 10–11

1.00*  0.61 1.12*  0.64 1.27*  0.95

0.86*  0.37 0.85*  0.64 1.19*  0.59

0.35  0.18 0.56  0.28 0.56  0.32

0.38  0.26 0.54  0.36 0.54  0.45

% shimmer p < 0.001

4–6 7–9 10–11

5.76*  2.33 4.72*  1.82 4.68*  1.81

4.36*  1.67 5.16*  2.58 4.80*  1.42

2.75  0.59 3.10  0.62 2.92  0.60

2.7  0.62 2.60  0.60 3.42  0.75

APQ p < 0.001

4–6 7–9 10–11

4.01*  1.54 3.31*  1.26 3.25*  1.21

2.99*  1.18 3.71*  2.31 3.38*  0.94

2.01  0.43 2.22  0.42 2.08  0.37

2.03  0.45 1.92  0.45 2.44  0.48

NHR p < 0.001

4–6 7–9 10–11

0.13*  0.02 0.13*  0.02* 0.14*  0.04

0.13*  0.03 0.14*  0.07 0.13*  0.03

0.12  0.01 0.13  0.02 0.12  0.02

0.11  0.02 0.12  0.01 0.12  0.02

SPI p < 0.001

4–6 7–9 10–11

3.87*  1.74 7.02*  3.30 9.72*  4.93

5.22*  2.50 6.64*  4.31 9.33*  5.14

3.19  1.46 7.04  3.55 8.47  5.24

4.01  1.55 4.64  2.44 4.43  1.81

*

p < 0.001- Bonferroni test.

varied degrees of dysphonia among 26 children, and GRBASI scale indicated slight hoarseness degree for 84.60% of them; breathiness and roughness were the most prevalent parameters. Some authors have emphasized the importance of the parameter strain for vocal nodules and recommended caution in the interpretation of the parameter breathiness due to the presence of posterior glottal closure [20,23].

In an interesting study, Masaki [24] attempted to characterize the impact of vocal nodules on child voices by using the sustained vowel/a/and the emission of sentences (pediatric version of CAPEV for children aged 4–6 years and 8–10 years). Two study groups were formed according to the age range: from 4 to 6 years and from 7 to 10 years. Each group had eight children with normal voices and eight children with vocal nodules, totaling 16 children with

316

A.C.J. Gramuglia et al. / International Journal of Pediatric Otorhinolaryngology 78 (2014) 312–316

nodules and 16 without laryngeal lesions. There was also a third group composed of 16 adult women (eight with nodules and eight without laryngeal lesions). That author noticed that the perceptual vocal parameters were capable of differentiating the voices of patients with nodules from normal voices, both for adults and for children, constituting a useful assessment method. Those results highlighted the importance of the parameter breathiness in child vocal analyses and roughness in vocal analyses of adults. The results of auditory-perceptual analyses also showed that some control children had slight alteration in the parameters G and B, indicating a certain degree of vocal change and breathiness in the voices of children without vocal symptoms and without changes in the vocal folds. These results corroborate the data reported by different authors [3,23]. In this study, expressive results were also obtained in the comparison of acoustic vocal analyses of children with nodules and children with normal voices. Except for f0, all the remaining acoustic parameters had higher values for children with nodules and could therefore be used to differentiate voices with nodules from normal voices (Table 4). Niedzielska [13] recorded higher values of jitter, shimmer and NHR in acoustic vocal analyses for children without symptoms, compared to children with diagnosed nodules. Similarly to our study, that author did not observe significant differences in the fundamental frequency values. Campisi et al. [10] recorded high values of jitter, RAP, PPQ, sPPQ and vF0 in acoustic vocal analyses of 33 children with vocal nodules. Valadez et al. [24] noted significant differences in the perceptual and acoustic vocal parameters of 6–10 year old children without laryngeal lesions, compared to children with vocal nodules. Following vocal therapy, these authors noted reabsorption of nodular lesions, proved by videolaryngoscopy, and improvement in perceptual and acoustic vocal analyses, especially regarding the values of f0, shimmer and jitter. Pereira-Jotz et al. [25] conducted videolaryngoscopy and acoustic vocal analysis for 50 children without vocal symptoms. They found high values of NHR for 30 children who also had altered videolaryngoscopic exams. Those authors valued the accuracy of this vocal parameter in the identification of dysphonia but emphasized the importance of a joint vocal analysis, acoustic and perceptual, for child dysphonia. Simo˜es-Zenai et al. [23] analyzed the voices of 50 dysphonic children aged between 4 and 11 years and compared the results of auditory-perceptual and acoustic vocal analyses to those of 50 children with normal voices, both within the same age range. For the control group, a certain degree of roughness, breathiness or tension was identified and these changes, when discreet, were considered normal for child voices. For dysphonic children, those authors noted more marked degrees of dysphonia that varied between G2 and G3, while acoustic vocal analyses recorded lower f0 values and increased emission noise. Acoustic vocal analyses have been greatly valued in the followup after treatment for children with vocal disorders. Tezcane et al. [14] analyzed the efficacy of vocal therapy done once a week for 39 children with vocal nodules (aged from 7 to 14 years) by means of auditory-perceptual (GRBAS scale) and acoustic (MDVP) analyses within three to six months after treatment. Vocal therapy improved all parameters of GRBAS scale, as well as jitter, shimmer, and noise-to-harmonic ratio (NHR), in acoustic analyses.

6. Conclusions The compromising of auditory-perceptual (G, R, B and S) and acoustic parameters (jitter, PPQ, shimmer, APQ, NHR and SPI) was greater for the voices of children with vocal nodules, compared to control children, indicating the importance of assessing these parameters for child dysphonia. TMF and f0 values did not differ between groups. References [1] P.N. Carding, S. Roulstone, K. Northstone, The prevalence of childhood dysphonia: a cross-sectional study, J. Voice 20 (2006) 623–630. [2] A. Connelly, W.A. Clemente, H. Kubba, Management of dysphonia in children, Laryngol. Otol. 123 (2009) 642–647. [3] E.L.M. Tavares, A. Brasolotto, M.F. Santana, C.A. Padovan, R.H. Martins, Epidemiological study of dysphonia in 4–12 year-old children, Braz. J. Otorhinolaryngol. 77 (2011) 736–746. [4] IuL. Soldatskiı˘, V.T. Sorokina, E.K. Onufrieva, OIu. Fedorova, I.E. Pogosova, V.V. Volod’kina, Hoarseness patterns in children, Vestn Otorinolaringol. 2 (2010) 28–31. [5] R.H.G. Martins, C.B. Hidalgo Ribeiro, B.M. Fernandes de Mello, A. Branco, E.L. Tavares, Dysphonia in children, J. Voice 26 (2012) 17–20. [6] A.L. Hamdan, R. Deeb, A. Sibai, C. Ramesh, H. Rifai, J. Fayyad, Vocal characteristics in children with attention deficit hyperactivity disorder, J. Voice 23 (2009) 190–194. [7] L. Czerwonka, J.J. Jiang, C. Tao, Vocal nodules and edema may be due to vibrationinduced rises in capillary pressure, Laryngoscope 118 (2008) 748–752. [8] M. Remacle, J.C. Degols, M. Delos, Exudative lesions of Reinke’s space. An anatomopathological correlation, Acta Otorhinolaryngol. Belg. 50 (1996) 253–264. [9] R.H.G. Martins, J. Defaveri, M.A.C. Domingues, R. de Albuquerque E Silva, A. Fabro, Vocal fold nodules: morphological and immunohistochemical investigations, J. Voice 24 (2010) 531–539. [10] P. Campisi, T.l. Tewfik, J.J. Manoukian, M.D. Schloss, E. Pelland-Blais, N. Sadeghi, Computer-assisted voice analysis, Arch. Otolaryngol. Head Neck Surg. 128 (2002) 156–160. [11] R.C. Oliveira, L.C. Teixeira, A.C. Gama, Ana´lise perceptivo-auditiva, acu´stica e autopercepc¸a˜o vocal em crianc¸as, J. Soc. Bras. Fonoaudiol. 23 (2011) 158–163. [12] D.K. Wilson, Children’s voice problems, in: Voice Problems of Children, 3rd ed., Williams & Wilkins, Philadelphia, 1987, pp. 1–15. [13] G.Y. Niedzielska, E.B. Glijer, A. Niedzielski, Acoustic analysis of voice in children with noduli vocales, Int. J. Pediatr. Otolaryngol. 60 (2001) 119–122. [14] C.Z. Tezcaner, S.K. Ozgursoy, I. Sati, G. Dursun, Changes after voice therapy in objective and subjective voice measurements of pediatric patients with vocal nodules, Eur. Arch. Otorhinolaryngol. 266 (2009) 1923–1927. [15] L.A. Goodman, On simultaneous confidence intervals for contrasts among multinomial populations, Ann. Math. Stat. 35 (2) (1964) 716–725. [16] L.A. Goodman, On simultaneous confidence intervals for multinomial proportions, Technometrics 7 (2) (1965) 247–254. [17] E.C. Madruga de Melo, M. Lemos, J. Araga˜o Ximenes Filho, L.U. Sennes, P.H. Nascimento Saldiva, D.H. Tsuji, Distribution of collagen in the lamina propria of the human vocal fold, Laryngoscope 113 (2003) 2187–2191. [18] M.S. De Bodt, K. Ketelslagers, T. Peeters, F.L. Wuyts, F. Mertens, J. Pattyn, et al., Evolution of vocal fold nodules from childhood to adolescence, J. Voice 21 (2007) 151–156. [19] M. Fuchs, M. Froehlich, B. Hentschel, I.W. Stuermer, E. Kruse, D. Knauft, Predicting mutational change in the speaking voice of boys, J. Voice 21 (2007) 169–178. [20] M. Behlau, R. Azevedo, P. Pontes, Conceito de voz normal e classificac¸a˜o das disfonias, in: M Behlau (Ed.), Voz - o livro do especialista, vol. I, Revinter, Rio de Janeiro, 2001. [21] E.L.M. Tavares, A.G. Brasolotto, S.A. Rodrigues, A.B. Benito Pessin, R.H. Garcia Martins, Maximum phonation time and s/z ratio in a large child cohort, J. Voice 26 (5) (2012) 675.e1–675.e4. [22] R.H. Colton, J.K. Casper, R. Leonard, Compreendendo os problemas da voz – Uma perspectiva fisiolo´gica no diagno´stico e tratamento das disfonias, Revinter, Rio de Janeiro, 2009. [23] M. Simo˜es-Zenari, K. Nemr, M. Behlau, Voice disorders in children and its relationship with auditory, acoustic and vocal behavior parameters, Int. J. Pediatr. Otorhinolaryngol. 76 (2012) 896–900. [24] V. Valadez, A. Ysunza, E. Ochara-Hernandez, N. Garrido-Bustamante, A. SanchezValerio, M.C. Pamplona, Voice parameters and videonasolaryngoscopy in children with vocal nodules: a longitudinal study, before and after voice therapy, Int. J. Pediatr. Otorhinolaryngol. 76 (2012) 1361–1365. [25] G. Pereira-Jotz, O. Cervantes, M. Abraha˜o, F.A. Parente Settanni, E. Carrara de Angelis, Noise-to-harmonics ratio as an acoustic measure of voice disorders in boys, J. Voice 16 (2002) 28–31.

Perceptual and acoustic parameters of vocal nodules in children.

Vocal nodules constitute the major cause of dysphonia during childhood. Auditory-perceptual and acoustic vocal analyses have been used to differentiat...
432KB Sizes 1 Downloads 0 Views