The usefulness of multi voice evaluation: Development of a model for predicting a degree of dysphonia.

OBJECTIVES: The purposes of this study were (1) to analyze the usefulness of self-report questionnaires, acoustic analysis, and auditory perceptual assessment for screening voice problems; and (2) to develop a new model for predicting a comprehensive voice severity using multi-assessment. METHODS: A total of 306 voice samples were analyzed in this study (typical group, n = 72; dysphonia group, n = 234). We performed a receiver operating characteristic analysis to determine the cutoff values of auditory perceptual assessments (visual analog scale), acoustic parameters (spectral- and cepstral-based analyses), and self-report questionnaires for screening voice disorders. We also performed a stepwise multiple regression analysis to verify which combination of parameters (acoustic parameters, and self-report questionnaires) could best predict perceived voice severity. RESULTS: We verified that most of the variables analyzed were useful for voice evaluation, and found to be useful for screening voice problems. Of these, a five-variable model was a useful to predict perceived voice severity (mean R2 = .807). The five-variable model consisted of acoustic parameters based on cepstral analysis (cepstral peak prominences in connected speech and sustained vowel task, and low versus high-frequency spectral energy ratio in connected speech task) and self-report questionnaires (total score of the Voice Handicap Index, and rumination score of the Voice Catastrophization Index). CONCLUSION: We verified that most of the variables were useful for screening dysphonia and five-variable model was a useful to predict perceived voice severity. The five-variable model could be used as an objective criterion for predicting voice severity.

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.

Correction: Theoretical and experimental study on the O(3P) + 2,5-dimethylfuran reaction in the gas phase.

Correction for 'Theoretical and experimental study on the O(3P) + 2,5-dimethylfuran reaction in the gas phase' by Andrea Giustini et al., Phys. Chem. Chem. Phys., 2021, 23, 19424-19434, DOI: 10.1039/D1CP01724A.

CO2 Activation Within a Superalkali-Doped Fullerene.

With the aim of finding a suitable synthesizable superalkali species, using the B3LYP/6-31G* density functional level of theory we provide results for the interaction between the buckminsterfullerene C60 and the superalkali Li3F2. We show that this endofullerene is stable and provides a closed environment in which the superalkali can exist and interact with CO2. It is worthwhile to mention that the optimized Li3F2 structure inside C60 is not the most stable C2v isomer found for the "free" superalkali but the D3h geometry. The binding energy at 0 K between C60 and Li3F2 (D3h) is computed to be 119 kJ mol-1. Once CO2 is introduced in the endofullerene, it is activated, and the O C O ^ angle is bent to 132°. This activation does not follow the previously studied CO2 reduction by an electron transfer process from the superalkali, but it is rather an actual reaction where a F (from Li3F2) atom is bonded to the CO2. From a thermodynamic analysis, both CO2 and the encapsulated [Li3F2⋅CO2] are destabilized in C60 with solvation energies at 0 K of 147 and < -965 kJ mol-1, respectively.

Theoretical and experimental study on the O(3P) + 2,5-dimethylfuran reaction in the gas phase.

In this work we report a joint experimental and computational study on the 2,5-dimethylfuran oxidation reaction in the gas phase initiated by atomic oxygen O(3P). The experiments have been performed by using vacuum-ultraviolet synchrotron radiation at the Advanced Light Source (ALS) of the Lawrence Berkeley National Laboratory (LBNL), at a temperature of 550 K and a pressure of 8 Torr. The experimental data were supported by quantum-chemical calculations along with a kinetic model, also taking into account the possible involvement of different magnetic states, performed in the framework of the RRKM theory. Propyne, acetaldehyde, methylglyoxal, dimethylglyoxal, 3-penten-2-one, 2,5-dimethylfuran-3(2H)-one, and 1,2-diacetyl ethylene have been identified as the main primary products arising under the conditions of the experiment. Our computational model suggests that these species can be formed at the concentration and branching ratio experimentally observed only in the presence of a non-negligible fraction of non-thermalized intermediates.

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.

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.

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.

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.

Computational investigation of LiF containing hypersalts.

This study explores the design of possible hypersalts starting from the hyperhalogen Li3F4 plus a Li atom and the hyperalkali Li4F3 plus a F atom. The investigation uses a multistep composite computational job that follows the same setup of the CBS-QB3 method, and uses B3LYP in combination with the CBSB7 + basis set for geometry optimizations. Adiabatic ionization energies (AIE), adiabatic electron affinities (AEA), HOMO-LUMO energy gaps, and NBO's are calculated for each presented species. Results confirm that the newly constructed hyperalkalis Li4F3, which has two isomers A and B, result in even lower AIE (3.83 eV and 3.65 eV for hyperalkali A and B, respectively) than the starting superalkali Li2F. The study also confirms the structures for the designed hyperhalogens Li3F4 (two isomers A and B) with higher AEA (7.70 eV and 5.63 eV for hyperhalogen A and B, respectively) than the superhalogen LiF2 building block. Hyperhalogens A and B in combination with a Li atom and hyperalkali A and B in combination with a F atom are used to create hypersalts. This yields three possible hypersalts A, B(C), and D with the formula Li4F4. Hypersalt A has the larger binding energy for dissociation into neutral fragments equal to 7.82 eV. Hypersalt C has the lower binding energy for dissociation into neutrals of 7.17 eV and hypersalt D the larger binding energy for dissociation into ions.

Capturing Volatile Organic Compounds Employing Superalkali Species.

In this study, the interactions between the superalkali species Li3 F2 and four volatile organic compounds (VOCs), methanol, ethanol, formaldehyde, and acetaldehyde, are assessed using the CBS-QB3 composite model. Adiabatic ionization energy (AIE), adiabatic electron affinity (AEA), binding energy (BE), charge transfer (▵q), and highest occupied molecular orbital and lowest unoccupied molecular orbital (HOMO-LUMO) gaps have been computed. Stronger interactions are observed between Li3 F2 and the aldehydes than alcohols. The smaller aldehydes show a larger BE with Li3 F2 than the bigger aldehydes. However, alcohol clusters do not show this trend due to their weak interactions (low BEs). Both alcohol clusters increase their binding energies as they become cations. This unexpected behavior is explained based on molecular orbital arguments.

Activation of Dinitrogen with a Superalkali Species, Li3 F2.

The capability of the superalkali Li3 F2 to activate dinitrogen (N2 ) is presented. The (Li3 F2 )nN2 clusters (n=1-6) were investigated first at the MP2/6-311+G(3d2f,2df,2p)//B3LYP/6-311G(2d,d,p) level of theory. Clusters up to n=4 were also optimized through the CBS-QB3 composite model. The complete dissociation of N2 was confirmed through visualized molecular orbitals and bond order calculation. The N-N bond is weakened by the addition of Li3 F2 superalkali units. The enthalpy of atomization ΔatH0∘ and formation (ΔfH0∘ ), charge flows (Δq), binding energies, and the energy gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital are calculated to help explain the N2 activation.

Reduction of carbon dioxide with a superalkali.

The ability of the superalkali Li3F2 to reduce (electron transfer) carbon dioxide (CO2) is presented. The CBS-QB3 composite method is employed to obtain reliable information on the geometries and energetics of the investigated species. Transition states and minima were located by scanning the potential energy surface for CO2 addition to the Li3F2 superalkali. The stability of Li3F2/CO2 is explained by high binding energy, charge flows, and the highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) gap. The selectivity of Li3F2 towards CO2 has also been computed by performing the same calculations for the most abundant atmospheric gas molecule N2. These results show a very small chemical affinity of Li3F2 for N2.

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.

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.

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.

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.

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.

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.