Assessing respiratory airflow unsteadiness under different tidal respiratory frequencies using large eddy simulation method.

Unsteady respiratory airflow characteristics play a crucial role in understanding the deposition of toxic particles and inhaled aerosol drugs in the human respiratory tract. Considering the variations in respiratory flow rate and glottis motion under different respiratory frequencies, these respiratory airflow characteristics are studied by large-eddy simulations, including pressure field, power loss, modal spatial patterns, and vortex structures. Firstly, the results reveal that varying respiratory frequencies significantly affect airflow unsteadiness, turbulent evolution, and vortex structure dissipation, as they increase the complexity and butterfly effect introduced by the turbulent disturbance. Secondly, the pressure drops and flow rate at the glottis also conform to a power-law relationship considering the respiratory physiological characteristics, especially under low respiratory frequencies. Glottis motion plays different roles in energy consumption during inspiration and expiration, and its magnitude can be predicted using a polynomial function based on glottis area and respiratory flowrate under different respiratory frequencies. Finally, modal decomposition can be effectively applied to the study of respiratory flow characteristics, but we recommend separately studying the inspiration and expiration. The spatial distribution of the dominant mode characterizes the majority of respiratory flow characteristics and are influenced by respiratory frequency. Spectral entropy results indicate that glottis motion and slow breathing both delay the transitions in the upper respiratory tract during inspiration and expiration. These results confirm that the respiratory physiology characteristics under different respiratory frequencies have a significant impact on the unsteady respiratory airflow characteristics and warrant further study.

[The effect of narrow band imaging in CO2 laser therapy in early-stage glottic cancer].

Objective:To explore efficacy of narrow band imaging（NBI） technique in CO2laser therapy in Early-Stage Glottic cancer. Methods:The clinical data of patients with Early-Stage Glottic cancer who underwent CO2laser vocal cord resection from June 2011 to August 2022 were retrospectively analyzed. Among these, 27 patients who underwent surgery assisted by NBI were assigned to the observation group, while 25 patients who underwent conventional CO2 laser microsurgery with a suspension laryngoscope were assigned to the control group. The differences between the two groups were analyzed in terms of intraoperative frozen pathology results, postoperative recurrence rates, 5-year cumulative disease-free survival rates, complications, and voice recovery. Results:All 52 patients were operated successfully. Temporary tracheostomy and serious complications did not occur during the operation. The postoperative patient's pronunciation was satisfactory. One patient experienced vocal cord adhesion, but there were no severe complications such as breathing difficulties or bleeding, with an overall complication rate of 1.92%. Postoperative follow-up was 1-5 years. The 5 years recurrence free survival in the general group was 77.90％, and the 5 years recurrence free survival in the NBI group was 100％, the difference was statistically significant（P<0.05）. NBI endoscopy is safer and more accurate than the general group in determining the safe margin of tumor mucosal resection（P<0.05）. Among the patients who accepted the voice analysis, the difference was no statistically significant（P>0.05）. Conclusion:Compared with conventional CO2laser surgery under microscope, NBI guided laser resection of Early-Stage Glottic cancer is more accurate. NBI guided laser resection could improve 5 years recurrence free survival rate. In a word, narrow-band imaging endoscopy can has very high value in clinical application.

Subglottic dilatation in extremely preterm infants on prolonged mechanical ventilation.

BACKGROUND: Airway injuries are reported among preterm infants with bronchopulmonary dysplasia. We hypothesized that prolonged ventilation in preterm infants is associated with subglottic dilatation that can be reliably evaluated by point of care ultrasonography (POCUS). METHODS: All preterm infants (<29-weeks) admitted to the neonatal ICU at the Advent-Health from January-2020 to June-2022 were eligible if they required invasive ventilation for ≤7 days in the first 28 days of life (control) or remained intubated for ≥28 days (prolonged ventilation). Sonography was performed by one technician and all images were reviewed by the pediatric radiologist. The trachea size was measured 3 times by randomly selecting three images. The first 20 scans were also independently reported by a different pediatric radiologist. Intra and inter-observer variability was estimated. Mean trachea size and weight at the time of imaging were compared. RESULTS: Out of 417 eligible infants; 11 died before 28 days and 163 required ventilation for 8-27 days. Consent missed for 80 infants during COVID-19 pandemic. We enrolled 23 and 28 infants in the control & prolonged ventilation groups, respectively. Inter and intra-observer correlations were 0.83 and 0.97 respectively. Infants in the control group had higher gestation and birth weight. Infants on prolonged ventilation were at higher risk for infections, BPD, longer hospital stay and significant subglottic dilation (4.51 ± 0.04 vs 4.17 ± 0.02 mm, p < 0.01) despite smaller body weight at the time of imaging (884 ± 102 vs 1059 ± 123g, p < 0.01). CONCLUSION: Extremely preterm infants on prolonged ventilation are at risk for sub-glottic dilatation that can be reliably measured by POCUS.

Clinical benefits of combining oral cytotoxic chemotherapeutic agents with radiotherapy in patients with T2N0 glottic squamous cell carcinoma based on the reports of the Head and Neck Cancer Registry of Japan.

BACKGROUND: T2N0 glottic squamous cell carcinoma (SCC) typically responds well to radiotherapy (RT); however, achieving local control remains challenging. In cases of RT failure, total laryngectomy may be necessary. Improved local control and preservation of the larynx directly enhances patients' quality of life. Our retrospective analysis using the Japan Head and Neck Cancer Registry (JHNCR) aimed to compare the clinical benefits of RT and chemoradiotherapy (CRT) in patients with T2N0 glottic SCC. METHODS: Using data from the JHNCR (2011-2015), we included 1,231 patients with T2N0 glottic SCC. Among them, 346 received curative RT and 425 underwent curative CRT. The CRT group was further divided into the oral CRT (Oral CRT, N=120) and intravenous CRT (DIV CRT, N=305) groups. This study assessed local control rate (LCR), progression-free survival (PFS), and overall survival (OS). A 1:1 propensity score-matching analysis was used to adjust for patient characteristics. RESULTS: After matching, 105 pairs compared RT with Oral CRT, and 224 pairs compared RT with DIV CRT. The variables were well-balanced in the matched populations. In the matched populations, the Oral CRT group had significantly better 5-year LCR and PFS than the RT group (LCR, 89.4 % vs. 80.6 %, P=0.043; and PFS, 85.5 % vs. 72.3 %, P=0.025, respectively), while the DIV RT group had significantly better 5-year PFS than the RT group (80.1 % vs. 68.6 %, P=0.026). CONCLUSIONS: The clinical benefits of better local and disease controls were observed when oral chemotherapy was added to RT in patients with T2N0 glottic SCC. Thus, the significance of adding oral chemotherapeutic agents to RT in the treatment of T2N0 glottic SCC requires further prospective investigation.

Factors Impacting Provider Treatment Decision-Making in Early Glottic Cancer.

OBJECTIVES: Transoral laser microsurgery (TLMS) and radiotherapy (XRT) are mainstays of treatment for early glottic carcinoma (EGC). Here, we investigated case-dependent provider treatment preferences and identify factors which impact decision-making in EGC. METHODS: This cross-sectional survey of laryngologists, head-and-neck surgeons, and radiation oncologists presented five diagrammatic cases of progressively advanced EGC (T1/2, N0). Respondents indicated preference for TLMS or XRT and ranked factors which influenced their recommendation for each case. Analysis utilized descriptive statistics, Fischer's exact tests, and Kruskal-Wallis tests for nonparametric data. RESULTS: A total of 141 complete responses (69.5% laryngologists) were received. Most respondents practiced in academic settings (93.5%) and within multidisciplinary teams (94.0%). Anterior commissure involvement was the most important a priori tumor factor for case-independent treatment recommendation (Likert Scale: 4.22/5), followed by Laterality (Likert Scale: 4.02/5). Across all specialties, TLMS was recommended for unilateral T1a lesions. Laryngologists continued recommending TLMS in T2 lesions (41.0%) more than head-and-neck surgeons (5.0%) and radiation oncologists (0.0%). Across all cases, survival and voice outcomes were the most important clinical factors impacting treatment decisions. Radiation oncologists weighed voice more heavily than laryngologists in more complex presentations of EGC (rank: 1.6 vs. 2.7, Kruskall-Wallis: p < 0.05). CONCLUSIONS: In more complex clinical presentations of EGC, preference for TLMS compared to XRT differed across specialists, despite similar rankings of factors driving these treatment recommendations. This may be driven by differing experiences and viewpoints on case-dependent voice outcomes following TLMS versus XRT, suggesting a need for increased understanding of how tumor location and depth impact voice outcomes. LEVEL OF EVIDENCE: 5 Laryngoscope, 134:3686-3694, 2024.

Hyperangulated vs. Macintosh videolaryngoscopy in adults with anticipated difficult airway management: a randomised controlled trial.

BACKGROUND: It is not certain whether the blade geometry of videolaryngoscopes, either a hyperangulated or Macintosh shape, affects glottic view, success rate and/or tracheal intubation time in patients with expected difficult airways. We hypothesised that using a hyperangulated videolaryngoscope blade would visualise a higher percentage of glottic opening compared with a Macintosh videolaryngoscope blade in patients with expected difficult airways. METHODS: We conducted an open-label, patient-blinded, randomised controlled trial in adult patients scheduled to undergo elective ear, nose and throat or oral and maxillofacial surgery, who were anticipated to have a difficult airway. All airway operators were consultant anaesthetists. Patients were allocated randomly to tracheal intubation with either hyperangulated (C-MAC D-BLADE™) or Macintosh videolaryngoscope blades (C-MAC™). The primary outcome was the percentage of glottic opening. First attempt success was designated a key secondary outcome. RESULTS: We assessed 2540 adults scheduled for elective head and neck surgery for eligibility and included 182 patients with expected difficult airways undergoing orotracheal intubation. The percentage of glottic opening visualised, expressed as median (IQR [range]), was 89 (69-99 [0-100])% with hyperangulated videolaryngoscope blades and 54 (9-90 [0-100])% with Macintosh videolaryngoscope blades (p < 0.001). First-line hyperangulated videolaryngoscopy failed in one patient and Macintosh videolaryngoscopy in 12 patients (13%, p = 0.002). First attempt success rate was 97% with hyperangulated videolaryngoscope blades and 67% with Macintosh videolaryngoscope blades (p < 0.001). CONCLUSIONS: Glottic view and first attempt success rate were superior with hyperangulated videolaryngoscope blades compared with Macintosh videolaryngoscope blades when used by experienced anaesthetists in patients with difficult airways.

Uncovering Gender-Specific and Cross-Gender Features in Mandarin Deception: An Acoustic and Electroglottographic Approach.

PURPOSE: This study aimed to investigate the acoustic and electroglottographic (EGG) profiles of Mandarin deception, including global characteristics and the influence of gender. METHOD: Thirty-six Mandarin speakers participated in an interactive interview game in which they provided both deceptive and truthful answers to 14 biographical questions. Acoustic and EGG signals of the participants' responses were simultaneously recorded; 20 acoustic and 14 EGG features were analyzed using binary logistic regression models. RESULTS: Increases in fundamental frequency (F0) mean, intensity mean, first formant (F1), fifth formant (F5), contact quotient (CQ), decontacting-time quotient (DTQ), and contact index (CI) as well as decreases in jitter, shimmer, harmonics-to-noise ratio (HNR), and fourth formant (F4) were significantly correlated with global deception. Cross-gender features included increases in intensity mean and F5 and decreases in jitter, HNR, and F4, whereas gender-specific features encompassed increases in F0 mean, shimmer, F1, third formant, and DTQ, as well as decreases in F0 maximum and CQ for female deception, and increases in CQ and CI and decreases in shimmer for male deception. CONCLUSIONS: The results suggest that Mandarin deception could be tied to underlying pragmatic functions, emotional arousal, decreased glottal contact skewness, and more pressed phonation. Disparities in gender-specific features lend support to differences in the use of pragmatics, levels of deception-induced emotional arousal, skewness of glottal contact patterns, and phonation types.

Measurement of the lengths of different sections of the upper airway and their predictive factors.

BACKGROUND: No studies have been conducted to define the lengths of the upper airway's different segments in normal healthy adults. AIMS/OBJECTIVES: This study aimed to determine the length of the subglottis and extrathoracic trachea and the factors affecting it. MATERIAL AND METHODS: This was an observational retrospective review study. Included 102 adult patients who underwent CT scan during the quiet inspiration phase of the upper airway. RESULTS: The results revealed significant positive linear relationships between height and both anterior and posterior subglottic measurements (p < 0.001). Additionally, a statistically significant, moderately strong negative correlation between age and extrathoracic tracheal measurements (p > 0.001) was observed. Men exhibited longer anterior (p < 0.001) and posterior (p > 0.001) subglottic measurements. In both sexes, the average length of the anterior subglottis was 14.16 (standard deviation [SD]: 2.72) mm, posterior subglottis was 14.51 (SD: 2.85) mm and extrathoracic trachea was 66.37 (SD: 13.71) mm. CONCLUSION AND SIGNIFICANCE: We concluded that a normal healthy adult's anterior subglottis length is 6.3-19.3 mm (mean: 14.16 [SD: 2.72] mm), posterior subglottis length is 6.1-20.0 mm (mean: 14.51 [SD: 2.85] mm) and extrathoracic trachea length is 25.2-98.5 mm (mean: 66.37 [SD: 13.71] mm). Age, height and sex affected the upper airway length.

Accelerated Fractionated Radiation Therapy for Localized Glottic Carcinoma.

BACKGROUND: The aim of this study is to examine the outcomes of an accelerated fractionated irradiation for N0 glottic carcinoma. METHODS: In this retrospective analysis, 29 patients with N0 glottic carcinoma treated by radiation therapy were enrolled. Thirteen patients had T1a disease, six had T1b disease, and ten had T2 disease. A fractional dose of 2.1 Gy was administered to seven patients. The total doses were 65.1 and 67.2 Gy in four and three patients, respectively. A fractional dose of 2.25 Gy was administered to 22 patients. The total doses were 63 and 67.5 Gy in 21 patients and 1 patient with T2 disease, respectively. Additionally, 13 patients underwent the use of TS-1 (80-100 mg per day). RESULTS: The median follow-up period was 33 months, and the 3-year local control rate was 95.6%. No patient had a lymph node or distant recurrence. As acute adverse events, grades 2 and 3 dermatitis were observed in 18 patients and 1 patient, and grades 2 and 3 mucositis were observed in 15 patients and 1 patient. As a late adverse event, one patient required tracheotomy because of laryngeal edema occurring. CONCLUSIONS: Accelerated fractionated irradiation may be an option in the radiation therapy of N0 glottic carcinoma because of its ability to shorten the treatment time.

Effects of Speech Characteristics on Electroglottographic and Instrumental Acoustic Voice Analysis Metrics in Women With Structural Dysphonia Before and After Treatment.

PURPOSE: Literature suggests a dependency of the acoustic metrics, smoothed cepstral peak prominence (CPPS) and harmonics-to-noise ratio (HNR), on human voice loudness and fundamental frequency (F0). Even though this has been explained with different oscillatory patterns of the vocal folds, so far, it has not been specifically investigated. In the present work, the influence of three elicitation levels, calibrated sound pressure level (SPL), F0 and vowel on the electroglottographic (EGG) and time-differentiated EGG (dEGG) metrics hybrid open quotient (OQ), dEGG OQ and peak dEGG, as well as on the acoustic metrics CPPS and HNR, was examined, and their suitability for voice assessment was evaluated. METHOD: In a retrospective study, 29 women with a mean age of 25 years (± 8.9, range: 18-53) diagnosed with structural vocal fold pathologies were examined before and after voice therapy or phonosurgery. Both acoustic and EGG signals were recorded simultaneously during the phonation of the sustained vowels /ɑ/, /i/, and /u/ at three elicited levels of loudness (soft/comfortable/loud) and unconstrained F0 conditions. RESULTS: A linear mixed-model analysis showed a significant effect of elicitation effort levels on peak dEGG, HNR, and CPPS (all p < .01). Calibrated SPL significantly influenced HNR and CPPS (both p < .01). Furthermore, F0 had a significant effect on peak dEGG and CPPS (p < .0001). All metrics showed significant changes with regard to vowel (all p < .05). However, the treatment had no effect on the examined metrics, regardless of the treatment type (surgery vs. voice therapy). CONCLUSIONS: The value of the investigated metrics for voice assessment purposes when sampled without sufficient control of SPL and F0 is limited, in that they are significantly influenced by the phonatory context, be it speech or elicited sustained vowels. Future studies should explore the diagnostic value of new data collation approaches such as voice mapping, which take SPL and F0 effects into account.

Effects of rosiglitazone on quality of life and prognosis of patients with early stage glottic laryngeal carcinoma.

Early-stage glottic laryngeal carcinoma refers to Tis-T2 lesions without cervical lymph nodes involvement and distant metastasis. Rosiglitazone facilitates expression of anti-inflammatory substances in the body, protecting immune system and improving patient's treatment efficacy and prognosis. We aimed to clarify the influence of rosiglitazone on prognosis of early-stage glottic laryngeal carcinoma. The control group received low-temperature plasma radiofrequency ablation and the observation group additionally received rosiglitazone; 4 mg, 2 times/day for 6 months. After treatment, the observation group showed reduction in the fundamental frequency perturbation and amplitude perturbation and increase in the harmonic-to-noise ratio relative to the control group. Total effective rate was 80.31% and 77.14% for observation and control groups, respectively (P > 0.05). Peripheral blood immune makers were higher in the observation group. The incidence rates of adverse reactions were lower in the observation group. The median survival time was 33 months in control group and 47 months in observation group (P < 0.05). The five-year survival rate was 77.14% in the observation group and 54.29% in the control group (P < 0.05). Rosiglitazone can prolong the survival of early-stage glottic laryngeal carcinoma patients, improving immune function and reducing adverse reactions during treatment.

Congenital glottic stenosis as a clinical manifestation of FREM1-associated disorders in a neonate with respiratory distress and aphonia.

A female infant born at 38 weeks and 2 days via induced vaginal delivery was admitted to the neonatal intensive care unit for respiratory distress soon after birth. Noted to have aphonia on examination, the patient underwent direct laryngoscopy and was diagnosed with an anterior glottic web and subglottic stenosis. The patient underwent a genetic workup including whole exome sequencing which resulted in a diagnosis of a FREM1-associated disorder. Congenital glottic webs and subglottic stenoses have not been previously described as clinical manifestations of FREM1-associated disorders.

The only "lungless" frog has a glottis and lungs.

Blackburn et al. show using CT-scanning that the only previously reported "lungless" frog retains a glottis and lungs.

Double lumen endobronchial tube intubation: lessons learned from anatomy.

BACKGROUND: Double lumen endobronchial tubes (DLTs) are frequently used to employ single lung ventilation strategies during thoracic surgical procedures. Placement of these tubes can be challenging even for experienced clinicians. We hypothesized that airway anatomy, particularly of the glottis and proximal trachea, significantly impacts the ease or difficulty in placement of these tubes. METHODS: Images from 24 randomly selected Positron Emission Tomography - Computed Tomography (PET-CT) scans were evaluated for several anatomic aspects of the upper airway, including size and angulation of the glottis and proximal tracheal using calibrated CT measurements and an online digital protractor. The anatomic issues identified were confirmed in cadaveric anatomic models. RESULTS: Proximal tracheal diameter measurements in PET-CT scans demonstrated a mean ± standard deviation of 20.4 ± 2.5 mm in 12 males and 15.5 ± 0.98 mm in 12 females (p < 0.001), and both were large enough to accommodate 39 French and 37 French DLTs in males and females, respectively. Subsequent measurements of the posterior angulation of the proximal trachea revealed a mean angle of 40.8 ± 5.7 degrees with no sex differences. By combining the 24 individual posterior tracheal angles with the 16 angled distal tip measurements DLTs (mean angle 24.9 ± 2.1 degrees), we created a series of 384 patient intubation angle scenarios. This data clearly showed that DLT rotation to a full 180 degrees decreased the mean intubation angle between the DLT and the proximal trachea from a mean of 66.6 ± 5.9 to only 15.8 ± 5.9 degrees. CONCLUSIONS: Rotation of DLTs a full 180 instead of the recommended 90 degrees facilitates DLT intubations.

Spectro-acoustic voice parameters in transoral laser microsurgery vs exclusive radiotherapy for early-stage glottic carcinoma: A systematic review and meta-analysis.

PURPOSE: In early glottic squamous cell carcinoma, similar results have been described in terms of disease control between transoral laser microsurgery (TLM) and radiation therapy (RT). During the past two decades, several studies compared subjective vocal outcomes of exclusive RT with those of TLM, showing a trend towards improving results for TLM over time. However, the objective differences in terms of spectro-acoustic voice parameters between exclusive RT and TLM have been less frequently investigated. The aim of this systematic review with meta-analysis was to evaluate voice quality after TLM and RT treatment for early glottic carcinoma, based on acoustic analysis parameters including jitter, shimmer, noise to harmonic ratio, fundamental frequency and maximum phonation time. MATERIAL AND METHODS: A search of the English published literature was conducted on the Pubmed, Scopus and Cochrane databases following PRISMA guidelines. RESULTS: A total of 441 titles were retrieved from the search. After full-text screening and application of inclusion/exclusion criteria, 12 articles were included. We found no significant differences between TLM and RT treatment in the considered acoustic analysis parameters, except for Shimmer, with more favorable values reported in the RT group. CONCLUSIONS: Considering the spread of the disease and expecting an improvement in long-term survival over time, well-designed and multicentric studies involving larger populations with a long-term follow up are mandatory to better assess objective voice outcomes in terms of spectro-acoustic voice parameters.

Oncological Outcomes of Transoral Laser Microsurgery for Early Stage Glottic Cancer with Involvement of the Anterior Commissure.

OBJECTIVES: To assess the value of carbon dioxide transoral laser microsurgery (CO2 TOLMS) for early-stage glottic cancer with special regard to involvement of the anterior commissure (AC). STUDY DESIGN: Single-center retrospective cohort study. SETTING: Grade-A tertiary hospital. METHODS: A retrospective analysis of patients with early-stage (Tis-T2) glottic cancer who underwent CO2 TOLMS. All patients had at least 2 years of follow-up. The univariate and multivariate survival analyses were used to identify the risk factors for recurrence and the Kaplan-Meier method was used to analyze OS and DSS rates. RESULTS: A total of 102 patients were included in the study. Eleven patients (10.78%) had recurrence. The univariate analysis showed that the recurrence was associated with the AC classification, T staging, tumor size, and tobacco use (P < .05). However, on multivariate analysis, the AC classification was the only independent risk factor for recurrence (P < .001, HR = 3.179). AC classification were distributed as follows: 59 (57.84%) AC0, 29 (28.43%) AC1, 8 (7.84%) AC2, and 6 (5.88%) AC3, 2-year/5-year OS and DSS rates were progressively reduced in the AC0, AC1, AC2, and AC3 groups (P < .001). At the same T staging, the OS rates incrementally decreased as the level of involvement of the AC became higher (P = .004). CONCLUSION: CO2 TOLMS is an effective treatment for early-stage glottic cancer. AC involvement is an independent risk factors for recurrence and poor prognosis. The AC classification system may be better at grading the prognosis of patients with early-stage glottic cancer and has prognostic value independent of T staging.

A Retrospective Study of Acoustic Measures of Glottal Stop Production to Assess Vocal Function in Unilateral Vocal Fold Paresis/Paralysis Patients.

PURPOSE: The aim of this study was to determine (a) diagnostic accuracy of acoustic measures of glottal stop production (GSP; intensity differences, slopes, complete voicing cessation) to distinguish between unilateral vocal fold paresis/paralysis (UVFP) patients and controls; (b) if acoustic measures of GSP significantly correlated with an acoustic measure of voice disorder severity, acoustic voice quality index (AVQI); and (c) if acoustic measures from another type of voicing cessation, voiceless consonant production, also significantly differed between groups. METHOD: Ninety-seven patients with unilateral paresis/paralysis and 35 controls with normal laryngostroboscopic signs produced two sets of five repeated [i] and four repeated [isi]. Tokens were randomized by type between groups and analyzed blinded using a customized Praat program that computed intensity differences and slopes between vowel maxima and glottal stop minima for inter-[i] tokens and vowel maxima and voiceless consonant minima for intra-[isi] tokens. The number of voicing cessations for inter-[i] tokens was obtained. RESULTS: Onset and offset intensity differences and number of voicing cessations from inter-[i] tokens had the greatest areas under the curve (.854, .856, and .835, respectively). Correlation coefficients were significant (p < .01) between AVQI and all GSP acoustic measures with weak/medium effect sizes. No significant differences were found between controls and participants with UVFP for acoustic measures from intra-[isi]. CONCLUSIONS: Acoustic GSP measures demonstrated good diagnostic accuracy and some relationship to severity of voice disorder. No significant differences in acoustic measures for medial voiceless fricative consonants between controls and participants with UVFP suggested that voicing cessation for voiceless fricatives differs from voicing cessation for GSP.