Vocal Fold Vibration Research Articles

Comparison of ultrasonic isolation calls of pure-breeding and interspecies hybrid Phodopus dwarf hamster pups

In mammalian cross-species hybrids, parameters of voice calls, produced by vocal fold vibrations, are intermediate between parental species. Inheritance of ultrasonic calls, produced by whistle mechanism, is unstudied for hybrids. We examined 4000 pup ultrasonic isolation-induced calls for peak power of call fundamental frequency and for call duration in 4–8-day-old captive hamsters of four Study Groups: pure Phodopus sungorus; pure P. campbelli of two populations (Mongolian and Kosh-Agach) and hybrids between male P. sungorus and female P. campbelli (Kosh-Agach). All Study Groups produced two categories of ultrasonic calls: Low-Frequency centered around 41 kHz and High-Frequency centered around 60 kHz, but in different percentages. Between populations, only Low-Frequency calls were shorter and higher-frequency in Mongolian P. campbelli. Between species, only High-Frequency calls were shorter and higher-frequency in P. sungorus. In hybrids, Low-Frequency calls were shorter and lower-frequency than in either parental species, whereas High-Frequency calls were longer and lower-frequency in hybrids than in pure P. sungorus but similar with another parental species. We discuss that interspecific hybridization may give rise to offspring with new properties of ultrasonic calls.

The realisation and phonetic features of the glottal stop in Bahdini Kurdish


 
 
 In Bahdini Kurdish (henceforth, BK), the realisation and the phonetic features of the glottal stop (GS) has not been extensively investigated and there is a debate about its phonemic status. In one hand, it is considered a phoneme that occurs only in a word-initial position. On the other hand, it is not con- sidered a phoneme but optionally produced at the beginning of vowel-initial words and does not affect meaning. The study aims at identifying the realisation of this sound experimentally, analyses its acous- tic features and whether it is affected by parameters such as vowel type, vowel position in the word and stress. The study is based on read speech produced by 10 BK native speakers. Then it is analysed phonetically using Praat to identify the presence/absence of the GS. Then the number of occurrences of the GSs are compared across vowel types, vowel position and stress. The results show that the GS is an epenthetic sound in BK that is inserted by the speakers to avoid onsetless syllables and to avoid vowel clusters. Different phonetic variations of the sound are realized in BK: A clear closure of the glottal stop, intermittent vocal folds vibrations during the GS closure, vocal folds vibrations start sim- ultaneously with the GS release. It appears not to be affected by stress but by position, as it is found more medially in V+V contexts than initially, and vowel quality as it is produced more before low vowels than non-low vowels.
 
 

Validation and enhancement of a vocal fold medial surface 3D reconstruction approach for in-vivo application

In laryngeal research, studying the vertical vocal fold oscillation component is often disregarded. However, vocal fold oscillation by its nature is a three-dimensional process. In the past, we have developed an in-vivo experimental protocol to reconstruct the full, three-dimensional vocal fold vibration. The goal of this study is to validate this 3D reconstruction method. We present an in-vivo canine hemilarynx setup using high-speed video recording and a right-angle prism for 3D reconstruction of vocal fold medial surface vibrations. The 3D surface is reconstructed from the split image provided by the prism. For validation, reconstruction error was calculated for objects located at a distance of up to 15 mm away from the prism. The influence of camera angle, changing calibrated volume, and calibration errors were determined. Overall average 3D reconstruction error is low and does not exceed 0.12 mm at 5 mm distance from the prism. Influence of a moderate (5°) and large (10°) deviation in camera angle led to a slight increase in error to 0.16 mm and 0.17 mm, respectively. This procedure is robust towards changes in calibration volume and small calibration errors. This makes this 3D reconstruction approach a useful tool for the reconstruction of accessible and moving tissue surfaces.

Air pressures that are critical in vocal fold vibration

As singers and speakers, we care about efficient ways to use our voices. Questions regarding the effective use of air pressure and airflow arise. For example: To get louder, is it just about pushing harder with more lung pressure? Or, are there other ways to tune up the system to get more bang for the buck? Let’s get some insights into various pressures in our airways.

A self-fused hydrogel for the treatment of glottic insufficiency through outstanding durability, extracellular matrix-inducing bioactivity and function preservation.

Injection laryngoplasty with biomaterials is an effective technique to treat glottic insufficiency. However, the inadequate durability, deficient pro-secretion of extracellular matrix (ECM) and poor functional preservation of current biomaterials have yielded an unsatisfactory therapeutic effect. Herein, a self-fusing bioactive hydrogel comprising modified carboxymethyl chitosan and sodium alginate is developed through a dual-crosslinking mechanism (photo-triggered and dynamic covalent bonds). Owing to its characteristic networks, the synergistic effect of the hydrogel for vocal folds (VFs) vibration and phonation is adequately demonstrated. Notably, owing to its inherent bioactivity of polysaccharides, the hydrogel could significantly enhance the secretion of major components (type I/III collagen and elastin) in the lamina propria of the VFs both in vivo and in vitro. In a rabbit model for glottic insufficiency, the optimized hydrogel (C1A1) has demonstrated a durability far superior to that of the commercially made hyaluronic acid (HA) Gel. More importantly, owing to the ECM-inducing bioactivity, the physiological functions of the VFs treated with the C1A1 hydrogel also outperformed that of the HA Gel, and were similar to those of the normal VFs. Taken together, through a simple-yet-effective strategy, the novel hydrogel has demonstrated outstanding durability, ECM-inducing bioactivity and physiological function preservation, therefore has an appealing clinical value for treating glottic insufficiency.

Recurrent Respiratory Papilloma of the Larynx

Recurrent respiratory papilloma (RRP) is a common benign neoplasm that most commonly affects the larynx. Caused primarily by human papilloma virus (HPV) types 6 and 11, RRP affects both children and adults; juvenile-onset RRP is thought to be related to HPV exposure during childbirth, whereas adult-onset disease has been hypothesized to be related to sexual contact.1Aaltonen L.M. Rihkanen H. Vaheri A. Human papillomavirus in larynx.Laryngoscope. 2002; 112: 700-707https://doi.org/10.1097/00005537-200204000-00020Crossref PubMed Scopus (83) Google Scholar Symptoms of RRP are typically voice or airway related. Adults tend to experience voice changes, primarily because of impairment of vocal fold vibration in the setting of papilloma along the membranous vocal folds. In children, in whom lesions tend to grow more quickly, airway narrowing may present with stridor in addition to voice changes. Direct or indirect laryngoscopy is standard work-up. Flexible fiberoptic or distal chip scopes may reveal heaped, irregular lesions of the glottis (Figure 1A) or supraglottis, and filters (eg, narrow-band imaging) (Figure 1B) may help to reveal intraepithelial capillary loops. Biopsy remains the criterion standard for diagnosis. Figure 2 illustrates typical findings, including a higher-power image of a cellular papillary frond with viral cytopathic effects and corresponding chromogenic in situ hybridization for low-risk HPV type 6/11.2Venkatesan N.N. Pine H.S. Underbrink M.P. Recurrent respiratory papillomatosis.Otolaryngol Clin North Am. 2012; 45 (671-94, viii-ix. https://doi.org/10.1016/j.otc.2012.03.006)Abstract Full Text Full Text PDF Scopus (89) Google Scholar Treatment includes excision or ablation with cold technique, photoangiolytic lasers, or microdebriders, with maximal conservation of the subepithelial vocal fold tissue. Recurrent respiratory papilloma routinely recurs, and so adjunct treatments with cidofovir and bevacizumab are advocated for recalcitrant cases.3Pogoda L. Ziylan F. Smeeing D.P.J. Dikkers F.G. Rinkel R.N.P.M. Bevacizumab as treatment option for recurrent respiratory papillomatosis: a systematic review.Eur Arch Otorhinolaryngol. 2022; 279: 4229-4240https://doi.org/10.1007/s00405-022-07388-6Crossref Scopus (3) Google Scholar Emerging evidence suggests that HPV vaccination, even in those already affected, may be beneficial in reducing the severity of disease.4Ponduri A, Azmy MC, Axler E, et al. The efficacy of human papillomavirus vaccination as an adjuvant therapy in recurrent respiratory papillomatosis. Laryngoscope. Published online January 18, 2023. https://doi.org/10.1002/lary.30560.Google Scholar The authors report no competing interests.

The Influence of Fiber Orientation of the Conus Elasticus in Vocal Fold Modeling.

While the conus elasticus is generally considered a part of continuation of the vocal ligament, histological studies have revealed different fiber orientations that fibers are primarily aligned in the superior-inferior direction in the conus elasticus and in the anterior-posterior direction in the vocal ligament. In this work, two continuum vocal fold models are constructed with two different fiber orientations in the conus elasticus: the superior-inferior direction and the anterior-posterior direction. Flow-structure interaction simulations are conducted at different subglottal pressures to investigate the effects of fiber orientation in the conus elasticus on vocal fold vibrations, aerodynamic and acoustic measures of voice production. The results reveal that including the realistic fiber orientation (superior-inferior) in the conus elasticus yields smaller stiffness and larger deflection in the coronal plane at the junction of the conus elasticus and ligament and subsequently leads to a greater vibration amplitude and larger mucosal wave amplitude of the vocal fold. The smaller coronal-plane stiffness also causes a larger peak flow rate and higher skewing quotient. Furthermore, the voice generated by the vocal fold model with a realistic conus elasticus has a lower fundamental frequency, smaller first harmonic amplitude, and smaller spectral slope.

Detecting Mild Phonotrauma in Daily Life.

The aim of this study was to gain quantitative insights into the role of daily voice use associated with mild phonotrauma via the Daily Phonotrauma Index (DPI), a measure derived from neck-surface acceleration magnitude (NSAM) and difference between the first two harmonic magnitudes (H1 - H2). An ambulatory voice monitor recorded weeklong voice use for 151 female patients with phonotraumatic vocal hyperfunction (PVH) and 181 female vocally healthy controls. Three laryngologists rated phonotrauma severity from each patient's laryngoscopy. Mixed generalized linear models evaluated the accuracy, sensitivity, and specificity of the original DPI trained on all patients versus a mild DPI version trained on only patients rated with mild phonotrauma. Individual contribution of NSAM and H1 - H2 to each DPI model was also evaluated. Reliability across the laryngologists' phonotrauma ratings was moderate (Fleiss κ = 0.41). There were 70, 69, and 12 patients with mild, moderate, and severe phonotrauma, respectively. The mild DPI, compared to the original DPI, correctly classified more patients with mild phonotrauma (Cohen's d = 0.9) and less controls (d = -0.9) and did not change in overall accuracy. H1 - H2 contributed less to mild phonotrauma classification than NSAM for mild DPI. Compared with the original DPI, the mild DPI exhibited higher sensitivity to mild phonotrauma and lower specificity to controls, but the same overall classification accuracy. These results support the mild DPI as a promising detector of early phonotrauma and that NSAM may be associated with early phonotrauma, and H1 - H2 may be a biomarker associated with vocal fold vibration in the presence of lesions. Level 4, case-control study Laryngoscope, 133:3094-3099, 2023.

High-Speed Image Analysis Comparing Loading of Vocal Folds During Coughing and Phonation: A Case Study

Coughing is related to voice problems, since it involves firm glottal closure, fast glottal opening, and high subglottic pressure and flow rate. In this study, the glottal area variation and movements of laryngeal structures during coughing and phonation are compared. High-speed laryngoscopy recordings were made of a normophonic male participant with a healthy larynx producing a neutral vowel and coughing. Oral air pressure was registered in a mouthpiece, through which an endoscope was inserted into the pharynx. Electroglottography, acoustic, and pressure signals were recorded simultaneously. The glottal width variation at the membranous and cartilaginous parts of the glottis was derived from the high-speed images, and the strong vibration of the false vocal folds was also registered. In coughing, compared to ordinary vowel phonation in nearly the same sound pressure level (93-94 dB6cm), the glottal width was 25% larger at the middle of the vocal folds, the maximum glottal opening velocity was 39% higher, and the maximum glottal width declination rate during glottal closing was up to three times higher. The maximum acceleration was 40% higher, and the maximum deceleration was 47% higher. Fundamental frequency f0 was the highest (ca. 400 Hz) at the beginning of the first phase of a typical coughing process. During the last part of the coughing process, f0 decreased from ca. 250 Hz to ca. 85 Hz at the phonation offset. The remarkable increase in maximum glottal width declination rate implies much higher vocal fold loading in coughing compared to phonation.

Analysis of a Soft Bio-Inspired Active Actuation Model for the Design of Artificial Vocal Folds

AbstractPhonation results from the passively induced oscillation of the vocal folds in the larynx, creating sound waves that are then articulated by the mouth and nose. Patients undergoing laryngectomy have their vocal folds removed and thus must rely on alternative sources of achieving the desired vibration of artificial vocal folds. Existing solutions, such as voice prostheses and the Electrolarynx, are limited by producing sufficient voice quality, for instance. In this paper, we present a mathematical analysis of a physical model of an active vocal fold prosthesis. The inverse dynamical equation of the system will help to understand whether specific types of soft actuators can produce the required force to generate natural phonations. Hence, this is referred to as the active actuation model. We present the analysis to replicate the vowels /a/, /e/, /i/, and /u/ and voice qualities of vocal fry, modal, falsetto, breathy, pressed, and whispery. These characteristics would be required as a first step to design an artificial vocal folds system. Inverse dynamics is used to identify the required forces to change the glottis area and frequencies to achieve sufficient oscillation of artificial vocal folds. Two types of ionic polymer-metal composite (IPMC) actuators are used to assess their ability to produce these forces and the corresponding activation voltages required. The results of our proposed analysis will enable research into the effects of natural phonation and, further, provide the foundational work for the creation of advanced larynx prostheses.

Enhancement in Speaker Identification through Feature Fusion using Advanced Dilated Convolution Neural Network

There are various challenges in identifying the speakers accurately. The Extraction of discriminative features is a vital task for accurate identification in the speaker identification task. Nowadays, speaker identification is widely investigated using deep learning. The complex and noisy speech data affects the performance of Mel Frequency Cepstral Coefficients (MFCC); hence, MFCC fails to represent the speaker characteristics accurately. In this proposed work, a novel text-independent speaker identification system is developed to enhance the performance by fusion of Log-MelSpectrum and excitation features. The excitation information is obtained due to the vibration of vocal folds, and it is represented using Linear Prediction (LP) residual. The various types of features extracted from the excitation are residual phase, sharpness, Energy of Excitation (EoE), and Strength of Excitation (SoE). The extracted features were processed with the dilated convolution neural network (dilated CNN) to fulfill the identification task. The extensive evaluation showed that the fusion of excitation features gives better results than the existing methods. The accuracy reaches 94.12% for 11 complex classes and 91.34% for 80 speakers, and Equal Error Rate (EER) is reduced to 1.16% for the proposed model. The proposed model is tested with the Librispeech corpus using Matlab 2021b tool, outperforming the existing baseline models. The proposed model achieves an accuracy improvement of 1.34% compared to the baseline system.

The f0 perturbation effects in focus marking: Evidence from Korean and Japanese.

Many studies showed that prosodic cues such as f0, duration and intensity are used in focus marking cross-linguistically. Usually, on-focus words exhibit expansions of acoustic cues such as f0 expansion, whereas post-focus words may show compression of acoustic cues. However, how features in a sub-syllabic level are employed in focus marking remain to be investigated. F0 perturbation refers to the phenomenon that vocal folds vibration is affected by the preceding non-sonorant consonant. The current study aims to examine how f0 perturbation is realized in focus marking in two languages Japanese and Korean. Tokyo Japanese is a pitch-accent language and Seoul Korean is considered to be at the stage of quasi-tonogenesis. Our results showed that f0 perturbation effects were enhanced in on-focus positions and compressed in pre- and post-focus positions for both narrow and contrastive focus in both languages. In addition, our results showed that pitch accent can also affect the realization of f0 perturbation in various focus conditions. Compared to Korean, our results in Japanese showed that f0 perturbation effects were less restricted. These results provide new insights into the current model of communicative functions that sub-syllabic level acoustic cues such as f0 perturbation can also be employed in focus marking.

The role of the tongue back on contrasting voicing properties of English coda consonants: Evidence from an ultrasound imaging technique

This study explores how voicing properties of stop consonants at the coda of a syllable are reflected in the articulation of the tongue back in American English. The association between the laryngeal control of the voicing property of consonants and the positioning of the tongue back has been increasingly reported (e.g., Ahn, 2018; Coretta, 2020). A recent study (Coretta, 2020) reported that longer vowel duration indicating the following voiced stop consonant corresponds to greater tongue root advancement at the offset of the vowel in Italian and Polish. Since the vowel with a following voiced stop consonant has a longer duration than that with a voiceless stop consonant, the later offset of TB movement should be correlated with the offset of vocal folds vibration in American English as well. The preliminary result suggests that the later offset of TB advancement is positively correlated with the longer vowel duration of voiced consonants at the coda of a syllable; therefore, contrasting voicing property of coda consonants in English is phonological and phonetically evidenced in the articulation of the tongue back. Articulatory data from ultrasound images of the tongue from three native speakers of American English will be presented.

Closed-loop network of skin-interfaced wireless devices for quantifying vocal fatigue and providing user feedback

Vocal fatigue is a measurable form of performance fatigue resulting from overuse of the voice and is characterized by negative vocal adaptation. Vocal dose refers to cumulative exposure of the vocal fold tissue to vibration. Professionals with high vocal demands, such as singers and teachers, are especially prone to vocal fatigue. Failure to adjust habits can lead to compensatory lapses in vocal technique and an increased risk of vocal fold injury. Quantifying and recording vocal dose to inform individuals about potential overuse is an important step toward mitigating vocal fatigue. Previous work establishes vocal dosimetry methods, that is, processes to quantify vocal fold vibration dose but with bulky, wired devices that are not amenable to continuous use during natural daily activities; these previously reported systems also provide limited mechanisms for real-time user feedback. This study introduces a soft, wireless, skin-conformal technology that gently mounts on the upper chest to capture vibratory responses associated with vocalization in a manner that is immune to ambient noises. Pairing with a separate, wirelessly linked device supports haptic feedback to the user based on quantitative thresholds in vocal usage. A machine learning-based approach enables precise vocal dosimetry from the recorded data, to support personalized, real-time quantitation and feedback. These systems have strong potential to guide healthy behaviors in vocal use.

Comparative Results of Vocal Fold Injury According to the Fiber-Based Laser in a Rabbit Vocal Fold Model

We assessed the safety of flexible fiber-based lasers including the potassium-titanyl-phosphate (KTP), CO2, and Holmium lasers using a rabbit vocal fold model and provided the safety evidence of laser before human clinical trial. In all, 120 male New Zealand white rabbits were used. Each laser was used to induce acute and chronic vocal fold injuries in 40 rabbits. The same laser energy with the same intensity and frequency were used in all cases, and we evaluated outcomes via surface scanning electron microscopy (SEM) and histological examination 1 day after injury. Histological and high-speed vocal fold vibration examinations were evaluated 1 month after injury. Surface injury roughness grading was done via SEM, and the Acute injury ratio and lamina propria (LP) ratio were also calculated. The dynamic glottal gap was measured through functional analyses based on recordings from a high-speed digital camera. The Holmium laser caused significantly more vocal fold damage than did the KTP and CO2 lasers as revealed by SEM and evaluation of acute and chronic injuries. Functional analysis with high-speed digital camera indicated that the holmium laser reduced dynamic glottal gap compared with the normal vocal fold, where the other lasers did not. The histological and functional analyses of rabbit vocal fold experiments indicated that fiber-based laryngeal laser surgery for vocal fold lesions could be performed relatively safely using a KTP or CO2 laser.

Influence of age on voice quality after transoral CO2 laser microsurgery

ObjectiveTo study the post-operative evolution of voice quality of patients treated by transoral CO2 laser microsurgery (TLM) according to the age.MethodsPatients treated by type I to VI TLM and post-operative speech therapy were prospectively recruited from our hospital. The voice quality was assessed pre-, 1-, 3- 6- and 12-month posttreatment with voice handicap index (VHI), dysphonia, roughness, breathiness, asthenia, strain (GRBAS), maximal phonation time (MPT), F0, F0 standard deviation (STD), percent jitter, percent shimmer, noise-to-harmonic ratio (NHR), vocal fold vibration assessment and speech fluency. Evolution of voice outcomes was analyzed considering age of patients (< 60 vs. ≥ 60 years).ResultsSeventy-five patients completed the evaluations. Thirty-four and forty-one patients were < 60 or ≥ 60 yo, respectively. Subjective and objective voice parameters (VHI, G, R, B), jitter and fluency significantly improved from 1- to 6-month post-TLM in < 60 yo individuals. The voice parameters improved 12-month post-TLM in the ≥ 60 yo group at the exception of VHI that improved 3-month post-TLM. There were positive associations between age and 12-month NHR, G and A parameters.ConclusionThe post-operative evolution of voice quality parameters may vary between patients according to the age. Preoperative VHI is predictive of 12-month subjective and objective voice outcomes.Graphical abstract

Change of Phonation in Canines Without Vocal Fold Paralysis After Vocal Processes Resection

The effects of the vocal processes resection on phonation in an animal without vocal fold paralysis have not been clarified. The present study used an in vivo animal model with vocal processes resection and excised larynges phonation model to investigate the effects of the vocal processes resection on phonation. Six months after resection of bilateral vocal fold processes, glottal airflow, subglottal air pressure, acoustic signals, and ultra-high-speed video images were recorded in the excised larynges phonation model of canine. Glottal aerodynamic parameters were estimated by calculation of subglottal pressure and glottal flow. Histological analyses of the scarred were assessed for wound healing completion. In the vocal processes resection group, fundamental frequency(F0) and vocal intensity decreased, and the Jitter and Shimmer increased significantly. The phonation threshold power(PTW) of the vocal processes resection was significantly higher than controls. The vibratory amplitude of the vocal fold posterior and visual vocal fold vibration length increased. Expression of collagen I-III in scarred tissue samples in vocal process resection was similar to controlling soft tissue specimens around vocal process cartilage, and collagen fiber formed matured thick bundles. The results suggest that the F0, voice quality, and vocal intensity significantly decreased after complete wound healing of vocal processes resection in canines without vocal folds paralysis. The higher PTW and posterior scarred vocal vibration may be the dynamic reasons.

A Quantitative Examination of Vocal Fold Vibratory Changes Using Two-Dimensional Scanning Digital Kymography After Angiolytic Laser Stripping for Vocal Fold Leukoplakia

Background and Objectives Vocal fold leukoplakia is characterized as white plaque on the epithelium of the vocal folds and can be treated by angiolytic laser stripping surgery. However, postoperative changes in the vibratory patterns of vocal folds have not been investigated quantitatively. The purpose of this study was to investigate the changes in vocal fold vibration after angiolytic laser surgery in patients with unilateral vocal fold leukoplakia using the twodimensional scanning digital kymography (2D DKG).Subjects and Method Medical records of seven males (age=62.14±12.40 yrs) with unilateral vocal fold leukoplakia who underwent angiolytic laser stripping were reviewed. Before and after the surgery (post-operative day=82.57±28.55 days), a multi-dimensional voice assessment was performed along with a 2D DKG study. For 2D DKG images, the amplitude symmetry index (ASI), phase symmetry index (PSI), and open quotient (OQ) were calculated using the ImageJ program. In addition, pre- versus postoperative data were compared, and the correlation between the changes in 2D DKG parameters and voice outcomes was explored.Results Results indicated that the absolute ASI (&lt;i&gt;p&lt;/i&gt;=0.028) and OQ (&lt;i&gt;p&lt;/i&gt;=0.028) of the 2D DKG study, grade (&lt;i&gt;p&lt;/i&gt;=0.038) and breathy (&lt;i&gt;p&lt;/i&gt;=0.034) of the GRBAS scale, σPitch measured by the electroglottography (&lt;i&gt;p&lt;/i&gt;=0.043), the physical score of the VHI (&lt;i&gt;p&lt;/i&gt;=0.042), and the total score (&lt;i&gt;p&lt;/i&gt;=0.043) and the tiredness score (&lt;i&gt;p&lt;/i&gt;=0.043) of the VFI decreased after surgery. Decrease in the absolute ASI was correlated with changes in the grade (rho=0.850) and breathy (rho=0.777) scale measures, while decreased OQ were correlated with the changes in the physical score of the VHI (rho=0.901) and tiredness score of the VFI (rho=0.847).Conclusion The improved vocal fold vibratory patterns after angiolytic laser surgery for vocal fold leukoplakia can be evaluated objectively using the 2D DKG study. Angiolytic laser stripping enables the preservation of vocal fold vibration after the surgery and is considered a valuable surgical option for treating vocal fold leukoplakia.

Effect of Controlled Muscle Activation in a Unilateral Vocal Fold Polyp Setting on Vocal Fold Vibration

Unilateral vocal fold polyps can lead to incomplete glottal closure and irregular vocal fold vibration. Depending on polyp size and resulting dysphonia severity, voice therapy or surgery may be recommended. As part of voice therapy, patients may learn how to optimize intrinsic and extrinsic laryngeal muscle use to mitigate benign lesion effects, increase vocal efficiency, and improve voice quality. In this study, we used a low-dimensional mass model with a simulated unilateral vocal fold polyp and varied intra-laryngeal muscle activity to simulate vocal fold vibration across varied conditions. Differing muscle activation has different effects on frequency, periodicity, and intensity. Accordingly, learning how to optimize muscle activity in a unilateral polyp setting may help patients achieve the best possible periodic and most efficiently produced voice in the context of abnormal vocal fold morphology.

Highly Stretchable, Transparent and Adhesive Ionogel Based on Chitosan-Poly(acrylic acid) Double Networks for Flexible Strain Sensors.

A stretchable double-network (DN) ionogel composed of a physically crosslinked network of chitosan (CS) and a chemically crosslinked network of polyacrylic acid (PAA) was prepared in an ionic liquid ([EMIM][OAc]) using a one-step polymerization method. In this ionogel (CS/PAA), the CS and the PAA polymer chains served as backbones, which constructed an interpenetrating DN structure via numerous hydrogen bonds formed through the hydroxyl, amino and carboxyl groups on the polymer chains. The DN structure improves the mechanical properties of the ionogel. Therefore, the CS/PAA DN ionogel exhibited outstanding mechanical performance in many ways: tensile strength up to 2.04 MPa, strain range up to 1046% and the value of toughness up to 8.52 MJ/m3. The ionogel also showed good self-recovery performance, fatigue resistance, ability to work in a broad temperature range (-20~80 °C) and adhesion properties. As a flexible sensor, the CS/PAA DN ionogel showed high strain sensitivity (gauge factor = 6.235). It can sensitively detect human motion (such as joint-bending, vocal fold vibration, walking gait and other human body motions), revealing the practical application potential of flexible electronic devices.