A Cepstral Analysis of Pathological Voice Quality in the Korean Population using Praat.

OBJECTIVES: This study aimed to investigate the reference values for cepstral peak prominence (CPP) and smoothed CPP (CPPS) measured using Praat in Korean speakers with the normal, healthy and pathological voice. METHODS: A total of 4,524 Korean participants with vocally healthy (n = 410) and dysphonic voices (n = 4,114) participated in this study. The speech task consisted of a sustained vowel /a/ and a sentence reading the Korean passage "Walk". CPP and CPPS values were quickly and automatically measured in sustained vowel and continuous speech tasks using Praat script. Furthermore, three veteran speech language pathologists (SLPs) scored the severity of dysphonia using the GRBAS scale (grade, roughness, breathiness, asthenia, strain) and Consensus Auditory Perceptual Evaluation of Voice (CAPE-V). RESULTS: Three SLPs showed high inter- and intra-rater reliabilities (IRR) in auditory-perceptual (A-P) evaluation. Significant differences were confirmed in CPP and CPPS between the normally healthy and pathological voice groups for both voice tasks (P < 0.01). The measured values of CPP and CPPS varied depending on the laryngeal pathology. In the receiver operating characteristic (ROC) curve analysis, the CPP_Vowel (CPP_V), CPPS_V, CPP_Sentence (CPP_S), and CPPS_S cut-off values were <21.5, <12.0, <19.7, and <10.1, respectively. Through ROC curve analysis, it was confirmed that CPP and CPPS had excellent diagnostic accuracy in distinguishing disordered voice (area under the ROC: 0.951-0.966). CONCLUSION: We investigated the reference values for CPP and CPPS measured with Praat for Korean speakers and confirmed that cepstral analysis is a promising tool for differentiating pathological voice.

Resonance Characteristics in Epiglottic Cyst: Formant Frequency, Vowel Space Area, Vowel Articulatory Index, and Formant Centralization Ratio.

OBJECTIVES: Resonance characteristics can change due to alterations in the shape of the vocal tract in patients with epiglottic cysts. This study aimed to analyze the resonance characteristics before and after the surgical excision of epiglottic cysts. METHODS: Twelve male patients with epiglottic cysts were enrolled in this study. We analyzed the first and second formants (F1 and F2) in vowels /a/, /e/, /i/, /o/, and /u/, vowel space area (VSA), vowel articulatory index (VAI), and formant centralization ratio (FCR). We measured these parameters before and after the surgical excision of epiglottic cysts. RESULTS: There was a significant increase in the F1 values of /a/, VSA, and VAI, and a significant decrease in the value of FCR after the surgery. CONCLUSION: We confirmed the change in the resonance characteristics in patients with epiglottic cysts. It is considered that further studies on epiglottic cysts and resonance changes are needed in the future.

Korean Voice Catastrophization Index (K-VCI): Validation of the Voice Catastrophization Index for Koreans.

OBJECTIVE: The purpose of present study was to validate a Korean version of the Voice Catastrophization Index for assessing catastrophization in patients with voice problems in a Korean population. METHODS: Case group patients with voice problems (n = 80) and control group patients without voice problems (n = 25) participated in the study. They were asked to complete three questionnaires: Korean Voice Handicap Index, Korean Voice-Related Quality of Life, and Korean Voice Catastrophization Index (K-VCI). Some of case group with voice problems completed the same three questionnaires again to assess test-retest reliability. Clinicians implemented the Consensus Auditory-Perceptual Evaluation of Voice evaluation to rate the overall severity on voice quality. RESULTS: K-VCI scores for case group were significantly higher than those for control group. K-VCI scores were significantly correlated with Korean Voice Handicap Index, Korean Voice-Related Quality of Life, and overall severity. The K-VCI had significant test-retest reliability and its internal consistency was good to excellent (range of Cronbach alpha correlation coefficients: 0.789-0.930). The K-VCI was not affected by patient sex, age, symptom duration, or diagnosis types. K-VCI scores were highest among patients with primary muscle tension dysphonia. CONCLUSION: We validated the K-VCI questionnaire for use in measuring the degree of catastrophization of voice problems in a Korean population. Future studies with a larger sample size will be necessary to further verify this and determine the clinical usefulness of the K-VCI.

Comparison of Cepstral Analysis Based on Voiced-Segment Extraction and Voice Tasks for Discriminating Dysphonic and Normophonic Korean Speakers.

OBJECTIVES: This study investigated whether there are differences in the discriminatory power of cepstral analysis according to the voiced-segment extraction method and voice tasks used for identifying dysphonic and normophonic Korean individuals. MATERIALS AND METHODS: A total of 2,863 subjects (2,595 subjects with and 268 subjects without dysphonia) were included in this study. The 3-second sustained vowel (SV) /a/ and one sentence of "Sanchaek" were edited and analyzed using Praat scripts. Cepstral analyses (cepstral peak prominence [CPP], smoothed cepstral peak prominence [CPPS], and low/high spectral ratio [LHRatio]) were performed using three voice tasks, namely, SV, continuous speech (CS), and extracted continuous speech (EXT) samples. Additionally, auditory-perceptual (A-P) assessments were performed by three speech language pathologists. RESULTS: Significant differences were found between dysphonic and normophonic voice groups for all cepstral parameters, except the LHRatio_EXT. Cepstral measurements of both SV and CS were highly correlated with A-P ratings. Furthermore, the diagnostic predictive power of CPP and CPPS for CS using the area under the receiver operating characteristic curve (AUC) was >0.919, the positive likelihood ratio (LR+) was ≥6.85, and the negative likelihood ratio (LR-) was ≤0.23. Additionally, for EXT, the AUC was >0.816, LR+ was 3.10, and LR- was ≤0.33. CONCLUSION: Both CS and EXT can predict dysphonia relatively well (r > 0.816). EXT showed lower predictability than the original sample (CS) analysis. Subsequent studies should implement voiced-segment extraction methods using various algorithms.

Comparison of Two Versions of the Acoustic Voice Quality Index for Quantification of Dysphonia Severity.

OBJECTIVES: The acoustic voice quality index (AVQI) is a specific acoustic indicator designed to objectively estimate dysphonia severity and measure the values of acoustic parameters based on the diagnostic category. This study compared the performance of two AVQI versions (2.02 and 3.01, v2 and v3) and PraatCPPS using a voice sample of Korean population. MATERIALS AND METHODS: Voice samples for sustained vowel and connected speech were elicited from 2257 patients across 14 diagnostic categories. Auditory-perceptual (A-P) assessments of dysphonia severity were compared to acoustic parameters of severity derived from two versions of the AVQI (v2 and v3) as well as the PraatCPPS. RESULTS: The AVQI-estimated severity (v2 and v3) and PraatCPPS severity for concatenated voice samples strongly correlated with each other and were significantly associated with A-P ratings. The AVQI (v2 and v3) and PraatCPPS showed high reliability in differentiating between pathological voice disorders. CONCLUSION: The AVQI (v2 and v3) and PraatCPPS were strongly correlated with the A-P ratings and provided valid estimates of dysphonia severity. However, the associations of the A-P ratings with the AVQIv2 were significantly stronger than those with the AVQIv3 and PraatCPPS, suggesting that the V2 outperformed the V3 and PraatCPPS.

Validation of the Acoustic Voice Quality Index in the Korean Language.

OBJECTIVE: The purpose of this study was to explore the concurrent validity of the Acoustic Voice Quality Index (AVQI) in a Korean population. We investigated the feasibility of its cutoff values and diagnostic accuracy in discriminating between normal and dysphonic voices. MATERIALS AND METHODS: A total of 1,524 native Korean subjects with normal voices (n = 113) and with voice disorders (n = 1,411) were asked to speak and sustain the vowel "a" and to read the Korean text "Walk" aloud. A 2-second mid-speech portion of the sustained vowel sound and two sentences (with 26 syllables) were edited and concatenated, and the AVQI was calculated. Additionally, two auditory-perceptual assessments, namely the Grade, Roughness, Breathiness, Asthenia, Strain scale, and the Consensus Auditory-Perceptual Evaluation of Voice were used by five speech language pathologists to rate the severity of dysphonia. RESULTS: Both auditory-perceptual assessments showed high confidence levels among the five speech language pathologists. The AVQI correlated with grade (G) and overall severity (OS). There were statistically significant differences in AVQI, G, and OS between normal and pathological speech groups. In the receiver operating characteristic curve analysis, AVQI, G, and OS cutoff values were <3.33, <0.00, and <22.00, respectively. The receiver operating characteristic curve analysis indicated that AVQI had excellent diagnostic accuracy for discriminating between normal and dysphonic voices (area under the curve: 0.970-0.977). CONCLUSIONS: We demonstrated the concurrent validity of AVQI as a promising tool for assessing overall voice quality and quantifying dysphonia in a Korean-speaking population.

Usefulness of Two-Dimensional Digital Kymography in Patients With Vocal Fold Scarring.

OBJECTIVE: Although laryngeal videostroboscopy is widely utilized in the analysis of vocal fold vibrations, it is often difficult to identify patterns of vocal fold vibrations in patients with aperiodic voice signals due to failure of synchronization during laryngeal videostroboscopy examination. Therefore, the present study aimed to compare the usefulness of simultaneous two-dimensional digital kymography (2D DKG) and traditional DKG for the detection of changes in the pattern of vocal fold vibrations in patients with vocal fold scarring (VFS). METHODS: Seven patients with VFS and one normal subject underwent high-speed videoendoscopy (HSV). DKG and 2D DKG evaluations of vocal fold vibrations were performed simultaneously, following which both qualitative and quantitative analyses were performed. RESULTS: Simultaneous DKG and 2D DKG enabled observation of vibratory patterns as well as amplitude and phase symmetry. DKG revealed and provided temporal information regarding the pattern of vocal fold vibrations at sites of VFS. In contrast, 2D DKG provided real-time information regarding the pattern of vibrations for the whole vocal fold region and regions of increased stiffness, as well as spatial information regarding changes in this pattern. CONCLUSION: Our findings indicate that 2D DKG enables the assessment of overall vocal fold vibrations, regardless of periodicity, and that simultaneous DKG and 2D DKG can be used to confirm abnormal patterns of vocal fold vibrations in patients with impaired flexibility and elasticity of the vocal folds.

Effects of Injection Laryngoplasty with Hyaluronic Acid in Patients with Vocal Fold Paralysis.

OBJECTIVES: The purpose of this study was to explore the effects of injection laryngoplasty (IL) with hyaluronic acid in patients with vocal fold paralysis (VFP). METHODS: A total of 50 patients with VFP participated in this study. Pre- and post-IL assessments were performed, which included analyzing the sustained vowel /a/ phonation, and the patient reading 1 Korean sentence from the "Walk" passage that comprised 25 syllables in 10 words. To investigate the effect of IL on vocal fold function, acoustic analysis (acoustic voice quality index, cepstral peak prominence, maximum phonation time, speaking fundamental frequency) was conducted and auditory-perceptual (grade and overall severity), visual judgment (gap), and self-questionnaire (voice handicap index-10) assessments were performed. RESULTS: The patients with VFP showed statistically significant differences between pre-and post-IL assessments for acoustic and auditory-perception, visual judgment, and self-questionnaire assessments. CONCLUSION: The patients with VFP showed positive change in vocal fold function between pre- and post-IL measurements. The findings showed that IL with hyaluronic acid is an effective method to improve vocal fold function in patients with VFP.

The cut-off analysis using visual analogue scale and cepstral assessments on severity of voice disorder.

Purpose: The aims of this study were to: (1) determine the visual analogue scale (VAS) and cepstrum peak prominence (CPP) cut-off points on the ratings of numerical scale (NS) related to the severity of voice disorder ratings and (2) verify the discriminative power of these cut-off points for distinguishing between different severities of voice disorder. Methods: Auditory-perceptual severity assessments (VAS and four-point NS) of 214 voice samples were performed by three speech-language pathologists and CPP parameters were used for the acoustic analysis. Both VAS and CPP cut-off points were obtained using receiver operating characteristic (ROC) curve analyses, based on their correspondence with NS ratings. Results: A high level of inter- and intra-rater reliability was found for the auditory-perceptual assessments of both VAS and NS. The VAS cut-off points for overall severity (OS), between normal variation and mild/moderate severity, mild/moderate and moderate severity, and moderate and severe severity were 32.7, 51.7, and 71.7 points, respectively, and CPP cut-off points were 7.050, 4.651, and 2.989 points, respectively. Areas under the ROC curves demonstrated excellent specificity and sensitivity of all cut-off points. Conclusions: The VAS and CPP cut-off points of OS of voice disorder demonstrated a high power to discriminate between different severities of voice disorder. The results of this study suggested cut-off points for clinical use.

Real-time Simultaneous DKG and 2D DKG Using High-speed Digital Camera.

INTRODUCTION: For the evaluation of voice disorders, direct observation of vocal cord vibration is important. Among the various methods, laryngeal videostroboscopy (LVS) is widely used, but it was not a true image because it collects images from different cycles. In contrast, high-speed videoendoscopy and videokymography have much higher frame rates and can assess functional and mobility disorders. OBJECTIVE: The purpose of the study is to describe real-time, simultaneous digital kymography (DKG), two-dimensional scanning (2D) DKG, and multi-frame (MF) LVS system using a high-speed digital camera, and identify the efficacy of this system in evaluating vibratory patterns of pathologic voice. METHODS: The pattern of vocal fold vibration was evaluated in a vocally healthy subject and in subjects with vocal polyp, vocal nodules, vocal cord scar, and vocal cord paralysis. We used both quantitative (left-right phase symmetry, amplitude symmetry index) and qualitative (anterior-posterior phase symmetry) parameters for assessment of vocal fold vibration. RESULTS: Our system could record videos within seconds and required relatively little memory. The speed of replay in the DKG, 2D DKG, MF LVS, and high-speed videoendoscopy was controllable. The number of frame per cycle with MF LVS was almost the same as the fundamental frequency. CONCLUSION: Our system can provide images of various modalities simultaneously in real time and analyze morphological and functional vibratory patterns. It can be possible to provide a greater level of information for the diagnosis and treatment of vibratory disorders.

Real-time dual visualization of two different modalities for the evaluation of vocal fold vibration - Laryngeal videoendoscopy and 2D scanning videokymography: Preliminary report.

OBJECTIVE: Currently, various tools have been introduced for the assessment of vocal fold vibration: laryngeal videolaryngoscopy (LV), videokymography (VKG), high speed videoendoscopy (HSV), digital videokymography (DKG), and 2D scanning videokymography (2D VKG). Among these, the authors have recently designed a dual modality examination system using LV and 2D VKG for more detailed information regarding the vibrations of the vocal folds. The clinical availability of this hybrid system offers medical imaging departments a range of potential advantages in the evaluation of vocal fold vibration. The obvious benefit of simultaneous acquisition is the improved integration of information that allows not only optimal anatomic localization, but also physical movement patterns. Other advantages include the lessened inconvenience to patients due to no longer requiring repeated examinations and shortening the examination time, and increased profitability. The purpose of study was to identify the efficacy of real-time dual examination of two different modalities for the evaluation of vocal fold vibration in human subjects and vocal fold vibration simulator. METHODS: One vocally healthy subject and three patients with vocal fold nodules, a vocal cyst, and vocal fold paralysis took part in this study. The vibratory patterns of the vocal folds were visualized using simultaneous real-time examination of two different modalities. Additionally, qualitative and quantitative analyses of the dual LV and 2D VKG images were performed. RESULTS: Real-time dual examination using a two modality system provided high definition images of the vibratory movements of the vocal folds. By assessing the obtained images, we confirmed that the dual modality examination method was useful in the evaluation of pathologic vibratory patterns, even in non-periodic phonation. CONCLUSION: The present system might improve the understanding of the processes of vocal fold vibration and make a contribution to pathologic voice research, as well as clinical practice.

A new videokymography system for evaluation of the vibration pattern of entire vocal folds.

OBJECTIVE: To overcome the limitations of previous videokymography methods, we developed a new videokymography system for the evaluation of the whole mucosal wave of the entire vocal cord mucous membrane. METHODS: To confirm the usefulness of the new videokymography system, we performed videokymography to evaluate the mucosal wave of the vocal folds during modal and falsetto phonation in normal adult males. Additionally, we serially performed both laryngeal videostroboscopy and the new videokymography method in patients diagnosed with acute ulcerative laryngitis. RESULTS: Using the new videokymography system, the mucosal wave pattern of entire vocal folds was captured during the examination. The opening and closing durations could be differentiated, and the symmetry of amplitude and phase could be assessed. The shape of the medial and lateral peaks could be assessed. In patients with acute laryngitis, the new videokymography system showed an enhanced ability to evaluate the flexibility of the vocal folds. CONCLUSION: The new videokymography system enables recording of the whole mucosal wave pattern of entire vocal folds. Although further studies are required to confirm its clinical efficacy for the evaluation of vocal folds, the system can be applied to evaluate the static and dynamic status of vocal folds in patients with vocal cord diseases.

The First Application of the Two-Dimensional Scanning Videokymography in Excised Canine Larynx Model.

OBJECTIVE: Evaluation of the vibratory pattern of vocal folds is of paramount importance to diagnose vocal fold disorders. Currently, laryngeal videokymography (VKG) and digital kymography from high-speed videolaryngoscopy are the available techniques for studying aperiodic vibrations of vocal folds. But VKG has the fundamental limitation that only linear portion of the vocal fold mucosa can be visualized. Digital kymography has the disadvantages of no immediate feedback during examination, considerable waiting time before kymographic visualization, recoding duration limited to seconds, and extreme demands on storage space. We developed a new system--two-dimensional (2D) scanning VKG--for evaluation of the vibratory pattern of vocal folds, and the method provided a possible alternative with its advantages and disadvantages. Thus, we aimed to evaluate the feasibility of the new device for the vocal fold vibration in excised canine larynx model. METHODS: The vibrating pattern for vocal folds was evaluated using high-speed videolaryngoscopic and 2D scanning videokymographic system in the excised canine larynx model. RESULTS: The images of canine vocal folds were captured with high-speed videolaryngoscopic system and converted to the kymographic images using the software. The kymographic image acquired by 2D scanning VKG was comparable with multi-line digital kymography at multiple locations. CONCLUSIONS: The vocal fold vibration could be evaluated in the excised canine larynx model using 2D scanning VKG. And this new device is expected to be a promising tool to evaluate the vocal fold vibration for clinical practice and voice research.

Imaging and Analysis of Human Vocal Fold Vibration Using Two-Dimensional (2D) Scanning Videokymography.

OBJECTIVE: Laryngeal videokymography and high-speed digital kymography are the currently available techniques for studying aperiodic vibration of the vocal folds. However, videokymography has a fundamental limitation that only linear portions of the vocal fold mucosa can be visualized, whereas high-speed digital kymography has the disadvantages of lack of immediate feedback during examination and considerable waiting time before kymographic visualization. We developed a new system, two-dimensional (2D) scanning videokymography, that provides a possible alternative for evaluation of the vibratory pattern of the vocal folds. Herein, we report the application of 2D scanning videokymography for visualization of vocal fold vibration in humans and an analysis of its parameters. MATERIALS AND METHODS: Two young healthy volunteers (one man and one woman) took part in this study. The vibratory patterns of their vocal folds were evaluated using 2D scanning videokymography and laryngeal stroboscopy. RESULTS: Two-dimensional scanning videokymography provided a high-definition image of the vibratory movements of the vocal folds. In analysis of the images acquired by the device, various parameters including fundamental frequency; ratio of the vibratory phases; phase, amplitude, and glottal area symmetry; and cycle-to-cycle variability were extracted. CONCLUSIONS: Our results indicate that 2D scanning videokymography is a useful and promising tool for visualization of the vibratory movement of the vocal folds. This new technique might improve our understanding of the mechanism of vocal fold vibration and contribute to voice research as well as clinical practice.

Changes and recovery of voice quality after sinonasal surgery.

Changes in the configuration of sinonasal cavity after surgery have been assumed to cause changes in the voice quality. The purpose of this study was to know when the hypernasality will be recovered after sinonsal surgery in patients with nasal septal deviation or chronic rhinosinusitis by checking long-term and serially obtained nasalance scores using nasometer. Sixty-five patients underwent sinonasal surgery were included. We classified the subjects into three groups according to the different surgical interventions employed: septoplasty group, endoscopic sinus surgery (ESS) group, and ESS with septoplasty group. The nasalance scores were obtained using a nasometer preoperatively, 1, 2, 3, 4, 5, and 6 months after surgery. The mean nasalance scores for vowels, nasal consonant, plosive consonant-vowel combinations, nasal consonant-vowel combinations, a hypernasality sentence, and hyponasality sentence increased significantly after sinonasal surgery. Hypernasality was most prominent in all groups for all acoustic parameters 1 month after surgery. Thereafter nasality decreased and returned to its preoperative level in all groups at 5 months in the [m], [ma], [mi], and hypernasality sentence, but at 6 months in the [a], [i], [u], [p(h)a], [p(h)i], and hyponasality sentence. Sinonasal surgery can change the acoustic characteristics of the vocal tract and produce a significant increase in nasality. After nasality showed the highest scores at 1-month post-surgery, it returned to its preoperative level at 5 or 6 months after surgery depending on the subtype of speech stimuli.

Intracordal auricular cartilage injection for unilateral vocal fold paralysis.

We evaluated the efficacy and outcome of intracordal auricular cartilage injection in patients with unilateral vocal fold paralysis. Our interest developed from findings of a canine model study that reported that histologic characteristics of cartilage were preserved 2 and 3 years after intracordal autologous cartilage injection. Between May 2002 and July 2010, 29 patients with breathy dysphonia caused by unilateral vocal fold paralysis underwent intracordal auricular cartilage injection. Each subject underwent preoperative and postoperative perceptual assessments, acoustical voice analysis, and videostroboscopy. Fourteen patients were male, and the mean age was 52-years old. Patients were tracked for a mean duration of 257 days. Injections were performed through a transoral approach under general anesthesia. Perceptual assessments by GRBAS scale, acoustic parameters of jitter, shimmer, noise-to-harmonic ratio, and maximum phonation time significantly improved at 3, 6, and 12 months after cartilage injection (p < 0.005). No major complications were observed after injection. Initial clinical results with intracordal auricular cartilage injection are promising for patients with unilateral vocal fold paralysis. Autologous auricular cartilage can be a safe, effective, and alternative material for vocal fold medialization, and can be a long lasting one.