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ORIGINAL ARTICLE
Year : 2020  |  Volume : 10  |  Issue : 2  |  Page : 27-33

A comparative study on steady and fluctuating semi-occluded vocal tract exercises between phonation of/a/and/E/


1 Masters in Audiology and Speech-Language Pathology, Ali Yavar Jung National Institute of Speech and Language Disabilities, (D), R.C, Kolkata, West Bengal, India
2 Lecturer in Speech and Hearing, Ali Yavar Jung National Institute of Speech and Language Disabilities, (D), R.C, Kolkata, West Bengal, India
3 Bachelor of Audiology and Speech-Language Pathology, Department of Speech and Hearing, Ali Yavar Jung National Institute of Speech and Language Disabilities, (D), R.C, Kolkata, West Bengal, India

Date of Submission07-May-2020
Date of Acceptance12-Dec-2020
Date of Web Publication18-Feb-2021

Correspondence Address:
Indranil Chatterjee
Ali Yavar Jung National Institute of Speech and Hearing Disability, (D), NILD Campus, B. T. Road, Bonhooghly, (Near State Bank ATM), Kolkata - 700 090, West Bengal
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jlv.jlv_3_20

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   Abstract 


Context: Semi-occluded vocal tract exercises (SOVTEs) helps to change the acoustic vocal tract impedance in relation to the glottal impedance, improving voice quality. SOVTE has been divided into two groups: steady and fluctuating SOVTEs based on their source of vibration and acoustic characteristics. Aims: The aim of the study was to examine and compare the difference between steady and fluctuating SOVTE with phonation of/a/and/E/on electroglottography and F1–F0 analysis. Settings and Design: Survey design. Study Type: Consort type of study. Materials and Methods: Hundred male participants within the age range of 18–25 years were selected for the study. All the participants were asked to phonate (a) and (E) vowels at a constant pitch for at least 3 s, then all samples were recorded. Assessment of contact quotient percentage value in electroglottography and PRAAT software were used for F1–F0 analysis. Data processing was done on Excel spreadsheet and scoring was processed by SPSS software. Statistical analysis used: One-way analysis of variance (ANOVA) in SPSS Statistics was used for statistical analysis. Results: Mean ± standard deviation and one-way ANOVA revealed that the significant difference was obtained at P < 0.05 in between the steady and fluctuating SOVTEs with phonation of/a/and/E/on EGG parameter and acoustic measure (F1–F0). Conclusions: The study suggested that contact quotient percentage and F1–FO (Hz) value in phonation of/E/are more than/a/. It indicates that phonation of/E/with SOVTEs has more effective in voice disorders than the phonation of/a/and that can be beneficial for treatment of organic voice disorders.

Keywords: Electroglottography, PRAAT, semi-occluded vocal tract exercises


How to cite this article:
Dhruw D, Chatterjee I, Chatterjee N. A comparative study on steady and fluctuating semi-occluded vocal tract exercises between phonation of/a/and/E/. J Laryngol Voice 2020;10:27-33

How to cite this URL:
Dhruw D, Chatterjee I, Chatterjee N. A comparative study on steady and fluctuating semi-occluded vocal tract exercises between phonation of/a/and/E/. J Laryngol Voice [serial online] 2020 [cited 2021 Jun 13];10:27-33. Available from: https://www.laryngologyandvoice.org/text.asp?2020/10/2/27/309677




   Introduction Top


Voice is an animate, subjective, living phenomenon which is one of the most important tools for communication. For most people, a well-functioning voice is an indispensable apparatus in their everyday life.[1] The human voice can be considered as an important manner of expression. Voice conveys a kaleidoscope of emotional undercurrents such as joy, excitement, irritation, suspicion, sympathy, apathy, humor, and hate. The human voice is a carrier of personality and identity.[2]

Voice evaluation protocol includes a detailed case history, screening, and various subjective and objective procedures. Screening includes evaluation of vocal characteristics related to respiration, phonation, and resonance, as well as vocal range and flexibility. Clinicians may use a formal screening tool or obtain data using informal tasks and standardized self-report questionnaires.[3] Assessment of voice includes various invasive and noninvasive procedures. Noninvasive procedures include many dedicated instruments and software programs which are used to obtain accurate and efficient results of the assessment of voice dynamic. One such software is PRAAT software which can be used to accurately estimate the fundamental frequency (F0) and the difference between the first formant (F1) from F0 (F1–F0) provided the voice is not too noisy.

Electroglottography (EGG) is a simple electrical method for the noninvasive examination of vocal fold phonatory vibration. It is an electrical method for studying the vocal fold vibratory movements, or rather vocal fold collisions and the time relations within and between those.[4] The electroglottograph consists of two electrodes which are placed on the thyroid cartilage. They help to record and measure vocal lip movement by using an alternating current of approximately 5 V between the two electrodes. The electroglottogram displays the opening and closing of the vocal lips and its 4 different phases. It also compares the open quotient, contact quotient, contact quotient range, and the relative average perturbation measured from the glottal area to that estimated from the EGG.

The management of voice includes three main areas of discussion, namely medical management, surgical management, and voice therapy. Our topic of discussion is voice therapy. Voice therapy program involves two approaches, namely direct approach, which focus on manipulating the voice-producing mechanisms (e.g., phonation, respiration, and musculoskeletal function) to modify vocal behaviors and establishing healthy voice production[5] and indirect approach includes patient education and counseling, which modifies the cognitive, behavioral, psychological, and physical environments in which voicing occurs.[6]

Semi-occluded vocal tract exercises (SOVTEs) have been mostly used as a therapeutic approach to reduce excessive tension on the vocal card and to facilitate voice quality.[7] SOVTEs are characterized by a reduction in the cross-sectional area of the distal part of the vocal tract.[8] This narrowing of the vocal tract promotes a feedback mechanism for the vibration of the vocal folds, which facilitates initiation of voice and self-sustained oscillations.[6] SOVTE has been divided between two groups, the single source of vibration and double source of vibration, and their acoustical characteristics is different from each other.[9] The steady (humming) exercise of SOVTE decreases the acoustical characteristics and increases the contact quotient (CQ) in muscles tension dysphonia. Other steady exercise like straw phonation increased the voice quality of professional voice users. In addition, SOVTE helps during warm-up before a performance by engaging breathing in professional voice users.[10] Another group of SOVTEs is fluctuating SOVTEs which makes use of a secondary source of vibration (double sources) that creates a Massaging effect on the vocal tract and the proprioceptive feedback.[11]

Great progress has been made toward understanding the effects of SOVTE, but still, there is uncertainty with regard to which of the SOVTE methods is best suited for each person or voice problem. Part of this dilemma comes from the great variety of SOVTE that have been suggested along the years (e.g., humming, hand over mouth, tongue trill, and lip trill); nowadays, SOVTEs have traditionally used to treat hyperfunctional and hypofunctional voice disorders. Some authors studied on different steady and fluctuating SOVTEs and phonation of/a/and/E/stated that the different SOVTEs had a different presentation. The current study attempts to provide an understanding toward the differences between steady and fluctuating SOVTEs with phonation of/a/and/E/, the inherent physiology, and the mechanism for relaxing the vocal cord structure.

The aim of this study was to examine and compare the steady and fluctuating SOVTEs with phonation of/a/and/E/with reference to EGG parameter and acoustic measure.

Aims and objectives

  1. To find the significant difference between steady and fluctuating SOVTEs with phonation of/a/and phonation of/E/, respectively, on electroglottography parameter (contact quotient)
  2. To find the significant difference between steady and fluctuating SOVTEs with phonation of/a/and phonation of/E/, respectively, on PRAAT software (F1–F0 analysis)
  3. To find the significant difference between phonation of/a/and/E/on electroglottography parameter (contact quotient) in all SOVTEs
  4. To find the significant difference between phonation of/a/and/E/on PRAAT software (F1–F0 analysis) in all SOVTEs.



   Materials and Methods Top


Research design

Survey.

Study type

CONSORT.

Participant's selection

Hundred male participants were taken for the study, within an age range of 19–25 years (mean age: 21.96 and standard deviation [SD] ± 2.096). Written consent was obtained from all the participants and the objective and need of the entire study was explained.

Inclusion criteria

The participants had normal oro-peripheral mechanism and hearing acuity within normal limits.

Exclusion criteria

Participants had any voice disorders by ENT examinations, any speech and language problem perceived swallowing disorder, and any cognitive or neurological problem were excluded from the study.

Procedure

Phase 1 – Calibration of equipment and subject preparation:

The EGG connected to the desktop computer model was used and calibrated as per the manufacturer's instructions before each data collection session. Participants were comfortably seated and the EGG electrodes were placed on their thyroid lamina.

Phase 2 – Instructions: The video demonstrations of all the exercises were shown to the participants before data collection. As a controlled exercise,/a/and/E/vowels were phonated followed by all exercises, selected randomly. All utterances were asked to be produced at a constant pitch for at least 3 s.

Phase 3 – Recording of sample:

All the voice samples were recorded by the sound recorder in a sound-treated room with the less ambient noise level in EGG, and then the data were fed to the PRAAT software.

Phase 4 – Data compilation: The electroglottographic values (contact quotient) of the voice samples were obtained for all the SOVTEs and the acoustic analysis (F1–F0) was done on PRAAT. Data processing was done on Excel spreadsheet. The scoring was processed by SPSS (Based in Chicago, SPSS Inc.; SYSTAT product) Version 20.0 to know the statistically significant difference between steady and fluctuating SOVTEs.

Phase 5 – Statistical analysis: Descriptive statistics was done to find the mean and SD values of steady and fluctuating semi-occluded exercises with phonation of/a/and/E/on electroglottography parameter (contact quotient) and acoustic measure (F1–F0 analysis).

One-way Analysis of Variance was done to see if there is a statistically significant difference between steady and fluctuating semi-occluded exercises with phonation of/a/and/E/on electroglottography parameter (contact quotient) and to see if there is a statistically significant difference between steady and fluctuating semi-occluded exercises with phonation of/a/and/E/on F1–F0 analysis in all exercises.


   Results Top


  1. To find the statistically significant difference between steady and fluctuating semi-occluded exercises with phonation of/a/and phonation of/E/, respectively, on electroglottography parameter (contact quotient).


The comparison between steady (humming and hand over mouth) and fluctuating (tongue trill and lip trill) SOVTEs with phonation of/a/and phonation of/E/on electroglottography parameter (contact quotient) clearly showed that the mean of steady SOVTEs was more than that of fluctuating SOVTEs.

The one-way ANOVA analysis revealed that there were statistically significant differences among the steady (humming and Hand over mouth) and fluctuating (tongue trill and lip trill) exercises with phonation of/a/and phonation of/E/on electroglottography parameter (contact quotient). It was, hereby, observed that the steady SOVTEs had more mean contact quotient percentage than the fluctuating SOVTEs, as depicted in [Figure 1].
Figure 1: Comparison between steady and fluctuating semi occluded vocal tract exercises with phonation of/a/and phonation of/E/on electroglottography parameter (contact quotient)

Click here to view


To find out the significant difference between steady and fluctuating semi-occluded exercises with phonation of/a/and phonation of/E/, respectively, on PRAAT software (F1-F0 analysis), a comparison between steady and fluctuating SOVTEs with phonation of/a/and phonation of/E/on electroglottography parameter (contact quotient) was performed.

The comparison between steady (humming and hand over mouth) and fluctuating (tongue trill and lip trill) SOVTEs with phonation of/a/and phonation of/E/on PRAAT software (F1–F0 analysis) suggested that the mean (F1–F0) values of fluctuating SOVTEs were more than that of steady SOVTEs. The ANOVA revealed that there were statistically significant differences among the steady and fluctuating exercises with phonation of/a/and phonation of/E/on PRAAT software (F1–F0 analysis). This suggests that the fluctuating SOVTEs have more F1–F0 values as compared to the steady exercises for both/a/and/E/phonation, respectively, which is depicted in [Figure 2].
Figure 2: Comparison between steady and fluctuating semi-occluded vocal tract exercises with phonation of/a/and phonation of/E/, respectively, on PRAAT software (F1–F0 analysis)

Click here to view


To find the statistically significant difference between phonation of/a/and/E/on electroglottography parameter (contact quotient) in all SOVTEs, a comparison between steady and fluctuating semi-occluded vocal tract exercises with phonation of/a/and phonation of/E/, respectively, on PRAAT software (F1–F0 analysis) was performed.

The statistical analysis showing comparison between steady and fluctuating SOVTEs with phonation of/a/and/E/on electroglottography (contact quotient) in all exercises revealed that the mean of phonation of/E/in all SOVTEs had more contact quotient percentage values than that of phonation of/a/in all SOVTEs. Moreover, the one-way ANOVA indicated that the contact quotient on EGG in humming/a/(steady SOVTEs), tongue trill/a/(fluctuating SOVTEs), and lip trill/a/(fluctuating SOVTEs) was significantly different from all four exercises with phonation of/E/, respectively. Furthermore, the one-way ANOVA indicated that there was a statistically significant difference between Hand over mouth (HOM)/a/(steady SOVTEs) and all the three exercises with phonation of/E/except humming/E/.

It is clear from the graph in [Figure 3]a, the mean of phonation of/E/in all SOVTEs had more contact quotient percentage values than that of phonation of/a/in all SOVTEs. The graph in [Figure 3]b reveals that only HOM/E/had more contact quotient percentage value than the HOM/a/. A graph in [Figure 3]c reveals that fluctuating (tongue trill/a/) had lower contact quotient percentage values than all SOVTEs with phonation of/E/. The graph in [Figure 3]d reveals that fluctuating (lip trill/a/) had a lower contact quotient percentage value than all SOVTEs with phonation of/E/.
Figure 3: Comparison between phonation of/a/and/E/on EGG (contact quotient) in all semi-occluded vocal tract exercises (a) Comparison between humming/a/vs. all four with/e/(b) Comparison between HOM/a/vs. all four with/e/(c) Comparison between tongue trill/a/vs. all four with/e/(d) Comparison between lip trill/a/vs. all four with/e/

Click here to view


To find the significant difference between phonation of/a/and/E/on PRAAT software (F1-F0 analysis) in all SOVTEs, a comparison was done between phonation of/a/and/E/on EGG (contact quotient) in all SOVTEs.

The comparison between steady and fluctuating SOVTEs with phonation of/a/and/E/on PRAAT software (F1-F0 analysis) in all exercises revealed that the mean of phonation of/E/in all SOVTEs had more F1–F0 values in PRAAT than that of phonation of/a/in all SOVTEs. The one-way ANOVA indicated that the F1–F0 values in humming/a/and hand over mouth/a/(steady SOVTEs) were significantly different from all four exercises with phonation of/E/, respectively. Furthermore, there was a statistically significant difference between tongue trill/a/(fluctuating SOVTEs) and lip trill/a/(fluctuating SOVTEs) and all three exercises with phonation of/E/except humming/E/. These findings are similar to that of the contact quotient percentage in EGG.

It was found in the graph of [Figure 4]a, the mean of phonation of/E/in fluctuating SOVTEs had more F1–FO (Hz) values than that of steady SOVTEs, while the Graph in [Figure 4]b posed only humming/E/that had lower value than the HOM/a/. The graph in [Figure 4]c posed fluctuating (tongue trill/a/) that had lower F1–FO value than tongue trill/E/. Similarly, the graph of [Figure 4]d posed fluctuating (lip trill/a/) that had lower F1–F0 value than lip trill/E/.
Figure 4: Comparison between phonation of/a/and/E/PRAAT software (F1-F0 analysis) in all semi-occluded vocal tract exercises (a) comparison between humming/a/and all four with/e/(b) comparison between HOM/a/and all four with/e/(c) Comparison between tongue trill/a/and all four with/e/(d) Comparison between lip trill/a/and all four with/e/

Click here to view



   Discussion Top


The study aimed is to investigate the comparison between steady and fluctuating SOVTEs with phonation of/a/and/E/in the normal population. The objectives were to examine and then compare the steady and fluctuating SOVTEs with phonation of/a/and/E/on contact quotient percentage (electroglottography) and F1–F0 (Hz) analysis (PRAAT software) using the voice sample from a total of 100 male participants. SOVTEs are divided into two groups consisting single-sourced exercises (humming, hand over mouth) and exercises with a secondary source of vibration added into the vocal tract (lip trills and tongue trills).

The findings of [Figure 1] suggested that there were statistically significant differences among the steady and fluctuating exercises with phonation of/a/and phonation of/E/on electroglottographic parameter (contact quotient) where the steady SOVTEs had more mean contact quotient percentage than the fluctuating SOVTEs.

When fluctuating exercises are produced using occlusion of anterior parts of the vocal tract (tongue or lip), the oral pressure increases and overcomes the force of occlusion, which is open and then moved inward by the speed of airflow. This movement possibly produces variations of pressure in the oral cavity, leading to oscillations of the closed quotient. Probably, this difference becomes more evident during high-intensity voice productions because of increased airflow. These findings were supported by Andrade et al., in their electroglottographic study of seven semi-occluded exercises: LaxVox, straw, lip trill, tongue trill, humming, hand over mouth, and tongue trill combined with hand over mouth found statistically significance differences in steady and fluctuating SOVTEs.[9]

The findings in [Figure 2] in PRAAT software show that F1–F0 values of fluctuating SOVTEs are significantly larger than the steady SOVTEs for phonation of both/a/and/E/vowel. In consonance to this, a comparative study done by Andrade et al., using electroglottographic parameters on seven semi-occluded exercises, where they also determined the difference between the first formant frequency and F0 (F1-F0), found larger F1–F0 differences in fluctuating SOVTEs than the steady SOVTEs.[9]

[Figure 3]a, [Figure 3]c, and [Figure 3]d revealed that the mean of phonation of/E/in all SOVTEs had more contact quotient percentage values than that of phonation of/a/in all SOVTEs with an only exception of [Figure 3]b where only HOM/E/had more contact quotient percentage value than the HOM/a/. These findings were in consonance with the study done by Cordeiro et al., on a comparative analysis of the closed quotient for lip and tongue trills in relation to the sustained vowel/E/; they concluded that there is oscillation of the closed quotient during the exercises of tongue and lip trills, and the closed quotient is higher during the performance of exercises of the lip trill when compared with the two other utterances only in the strong intensities.[12] Furthermore, a similar study done by Sundberg on vocal fold vibration patterns and modes of phonation suggested lower contact quotients in lip trills than in sustained vowels.[13]

The findings of [Figure 4]a, [Figure 4]c and [Figure 4]d also gave similar results as the previous one, but in PRAAT software, the phonation of/E/ had more F1–F0 values than the phonation of/a/, in both steady and fluctuating SOVTEs, except in the [Figure 4]b, where only humming (steady SOVTE) had lower values than hand over mouth (Fluctuating SOVTE) in phonation of /a/.

These results were in consonance with the study of Deliyski who concluded in his study that the restrain that happens to the glottal airflow tends to bring down the breathy component in voice, thereby improving the voice quality. Whereas when the reduction in the HNR is prolonged, it showed an increase in noise energy of the signal.[14]


   Conclusion Top


This study results revealed that steady (humming and HOM) SOVTEs exhibiting higher CQ percentage used a single source of vibration into the vocal tract (i.e., the vocal folds). The exercises show lower F1–F0 (HZ) values and thus theoretically higher positive vocal tract reactance, promoting an easy phonation. Fluctuating (tongue trill and lip trill) presents a lower CQ percentage. These make use of a secondary source of vibration into the vocal tract, which could be considered as the massage effect on the vocal organs. The fluctuating exercises revealed higher F1–F0 (Hz) values when compared with steady exercises, theoretically lower positive vocal tract reactance making the phonation less easy. It was found that the phonation of/a/and/E/in steady and fluctuating SOVTEs had posed different vocal folds movements during phonation, which indicated that the SOVTEs with phonation of/E/are more effective than the SOVTEs with phonation of/a/. However, the study also had certain limitations, such as only male subjects with a limited age range were taken. Furthermore, all the exercises were done within a single session. This study has numerous implications in the field of voice pathology and its management, such as it will give comparative scores obtained from F1, F0, and EGG measurements of steady and fluctuating exercises with phonation of/a/and/E/. In addition, it will help us to understand the differences between acoustic and EGG scores in steady and fluctuating exercises with phonation of/a/and/E/that will be implemented on voice therapeutics for better improvements in the organic voice disorders. This test result will help in the certain case with dysarthric patients those cannot produce/l/and/r/.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

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Carullo A, Astlfi A, Atzori A, Carlino V, Castellana A, Fabro C, et al. Objective assessment of the effect of semi-occluded vocal-tract techniques on vocal performances. 23rd Int Cong Acoust, Achen, Germany, 2019;23:1;7789-96.  Back to cited text no. 11
    
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Cordeiro GF, Montagnoli AN, Nemr NK, Menezes MH, Tsuji DH. Comparative analysis of the closed quotient for lip and tongue trills in relation to the sustained vowel/μ/. J Voice 2012;26:e17-22.  Back to cited text no. 12
    
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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]



 

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