Asymmetry of Occupational Noise Induced Hearing Loss: An Electrophysiological Approach

Abstract Introduction The question as to whether occupational noise exposure causes symmetrical or asymmetrical hearing loss is still controversial and incompletely understood. Objective Two electrophysiological methods (cortical evoked response audiometry: CERA and auditory steady state responses: ASSR) were used to address this issue. Method 156 subjects with a well-documented history of noise exposure, a wide range of noise induced hearing loss (NIHL) and without middle ear pathology underwent both a CERA and an ASSR examination in the context of an exhaustive medicolegal expert assessment intended for possible compensation. Results Whatever the method (CERA or ASSR), the average electrophysiological hearing thresholds (1-2-3 kHz) are significantly worse in the left ear. The right - left differences in CERA and ASSR thresholds are strongly correlated with each other. No significant effect of frequency is found. No correlation is observed between right - left differences in hearing thresholds and either age or degree of hearing loss. Conclusion In NIHL, there is an actual average right - left difference of about 2.23 dB, i.e., 3.2%, the left ear being more impaired.

Asymmetry of Occupational Noise Induced Hearing Loss: An Electrophysiological Approach.

Introduction The question as to whether occupational noise exposure causes symmetrical or asymmetrical hearing loss is still controversial and incompletely understood. Objective Two electrophysiological methods (cortical evoked response audiometry: CERA and auditory steady state responses: ASSR) were used to address this issue. Method 156 subjects with a well-documented history of noise exposure, a wide range of noise induced hearing loss (NIHL) and without middle ear pathology underwent both a CERA and an ASSR examination in the context of an exhaustive medicolegal expert assessment intended for possible compensation. Results Whatever the method (CERA or ASSR), the average electrophysiological hearing thresholds (1-2-3 kHz) are significantly worse in the left ear. The right - left differences in CERA and ASSR thresholds are strongly correlated with each other. No significant effect of frequency is found. No correlation is observed between right - left differences in hearing thresholds and either age or degree of hearing loss. Conclusion In NIHL, there is an actual average right - left difference of about 2.23 dB, i.e., 3.2%, the left ear being more impaired.

Machine Learning Assessment of Spasmodic Dysphonia Based on Acoustical and Perceptual Parameters.

Adductor spasmodic dysphonia is a type of adult-onset focal dystonia characterized by involuntary spasms of laryngeal muscles. This paper applied machine learning techniques for the severity assessment of spasmodic dysphonia. To this aim, 7 perceptual indices and 48 acoustical parameters were estimated from the Italian word /a'jwɔle/ emitted by 28 female patients, manually segmented from a standardized sentence and used as features in two classification experiments. Subjects were divided into three severity classes (mild, moderate, severe) on the basis of the G (grade) score of the GRB scale. The first aim was that of finding relationships between perceptual and objective measures with the Local Interpretable Model-Agnostic Explanations method. Then, the development of a diagnostic tool for adductor spasmodic dysphonia severity assessment was investigated. Reliable relationships between G; R (Roughness); B (Breathiness); Spasmodicity; and the acoustical parameters: voiced percentage, F2 median, and F1 median were found. After data scaling, Bayesian hyperparameter optimization, and leave-one-out cross-validation, a k-nearest neighbors model provided 89% accuracy in distinguishing patients among the three severity classes. The proposed methods highlighted the best acoustical parameters that could be used jointly with GRB indices to support the perceptual evaluation of spasmodic dysphonia and provide a tool to help severity assessment of spasmodic dysphonia.

Vocal Fold Collision Speed in vivo: The Effect of Loudness.

Mechanical impact stress on the vocal fold surface, particularly when excessive, has been postulated to cause the so-called phonotraumatic tissue lesions, such as nodules and polyps. The collision stress between the vocal folds depends on the vocal fold velocity at the time of impact. Hence this vocal fold collision speed is a relevant parameter when considering biomechanical economy of phonation, especially in voice professionals needing a louder voice than normal. Combining a precise photometric measurement of glottal area and simultaneous measurements of translaryngeal impedance (electroglottogram) for identifying the time of the maximum rate of increase of vocal fold contact allows computing the vocal fold collision speed in a wide range of loudnesses. The vocal fold collision speed is - for modal voicing - always smaller than the maximum vocal fold velocity during the closing phase, but it strongly increases with intensity. Moreover, this increase shows a biphasic pattern, with a significant enhancement from a certain value of dB on. Understanding physiological variables that influence vocal fold collision forces provides relevant insight into the pathophysiology and the prevention of voice disorders associated with phonotraumatic vocal hyperfunction.

Semioccluded Vocal Tract Exercises Improve Self-Perceived Voice Quality in Healthy Actors.

PURPOSE: Semi-occluded vocal tract exercises (SOVTE) have shown to lead to more effective and efficient vocal production for individuals with voice disorders and for singers. The aim of the present study is to investigate the effects of a 10-minute SOVTE warm-up protocol on the actors' voice. METHODS: Twenty-seven professional theater actors (16 females) without voice complaints were audio-recorded while reading aloud, with their acting voice, a short dramatic passage at four time points. Recordings were made: the day before the show, just before and soon after the warm-up protocol which was performed prior to the show and soon after the show. The voice quality was acoustically and auditory-perceptually evaluated and quantified at each time point by blinded raters. Self-assessment parameters anonymously collected pre and post exercising were also analyzed. RESULTS: No statistically significant differences on perceptual ratings and acoustic parameters were found between pre/post exercise sessions and males/females. A statistically significant improvement was detected in the self-assessment parameters concerning comfort of production, sonorousness, vocal clarity and power. CONCLUSIONS: Vocal warm-up with the described SOVTE protocol was effective in determining a self-perceived improvement in comfort of production, voice quality and power, although objective evidence was missing. This straightforward protocol could thus be beneficial if routinely utilized by professional actors to facilitate the voice performance.

Intraglottal Aerodynamics at Vocal Fold Vibration Onset.

The most frequently observed type of voice onset in spontaneous speech in normal subjects is the soft onset, and it may be considered as the "physiological" onset. It starts from an immobile narrow glottal slit crossed by a continuous airflow, and then a few oscillations (even a single one in some cases) precede the first glottal closure. It is a transient event, during which the acting forces, lung pressure, intraglottal pressure, myoelastic tension of the vocal fold (VF) oscillator and inertance of the supraglottal vocal tract, interact to progressively reach the steady state of a sustained oscillation. Combined measurements of flow, area, and pressure provide a detailed qualitative and quantitative analysis of the intraglottal mechanical events at the precise moment of starting oscillation in a physiological (soft or soft/breathy) onset. Our in vivo measurements of airflow and glottal area show that the very first oscillation occurs exactly at the time when turbulence appears at the level of the glottal narrowing, ie, when the Reynolds number reaches its critical value. The turbulence may be assumed to trigger an oscillator consisting in the ensemble of the VFs and the air of the vocal tract, which is known to be weakly damped. Turbulence can act here as an aspecific flick, triggering the oscillator, the frequency of oscillation being determined by its mechanical properties. Furthermore, the first noticeable glottal oscillations are sinusoidal: the VFs are neither steeply sucked together by a negative Bernoulli pressure, nor burst apart by the lung pressure. Our measurements show that, at the critical time, the rising positive lung pressure is balanced by the rising negative Bernoulli pressure generated by the transglottal flow.

The Atopy Index Inventory: A Brief and Simple Tool to Identify Atopic Patients.

INTRODUCTION: Atopy and ear, nose and throat (ENT) diseases are frequently associated; however, no clinical tool has been proposed so far to discriminate which patients could be atopic and therefore deserving of a further immunoallergological evaluation. OBJECTIVE: The aim of this study was to assess and validate a set of dichotomous responses suitable for predicting the presence of atopy in adult patients. METHODS: An 11-item questionnaire, i.e., the Atopy Index Inventory (AII), comprised of 4 questions regarding the clinical history for allergic disease and 7 questions evaluating the presence of the most frequent clinical signs affecting allergic patients, was developed and administered to 226 adult subjects (124 atopic subjects and 102 healthy, not atopic subjects). The atopic condition was proven by an immunoallergological evaluation according to the diagnostic criteria of the EAACI guidelines. Internal consistency and clinical validity were tested. RESULTS: In healthy subjects, the first 4 variables of the AII returned a 100% correct response (all answered "no") and were defined as "decisive" responses. In the logistic regression analysis, when decisive items were negative, the atopic condition was confirmed when answering "yes" to at least 3 "probability" items (cut-off = 2.69). The difference in AII scores between allergic and healthy group was significant using the Mann-Whitney U test (p < 0.0001). The sensitivity and specificity of the AII were 0.97 and 0.91, respectively, with a true predictive value of 0.92 and a false predictive value of 0.97. The ROC curve showed an area of 0.94, with an OR of 0.88 (95% CI 0.87-0.97, p = 0.0001). The internal consistency as determined by the Cronbach α coefficient was 0.88. CONCLUSION: The AII has been proven to be a brief, simple and sufficiently accurate tool for screening ENT patients in search of atopic individuals and to allow their clinical management.

In Vivo Quantification of the Intraglottal Pressure: Modal Phonation and Voice Onset.

Intraglottal pressure is the driving force of vocal fold vibration. Its time course during the open phase of the vibratory cycle is essential in the mechanics of phonation, but measuring it directly is difficult and may hinder spontaneous voicing. However, it can be computed from the in vivo measured transglottal flow and glottal area (hence the air particle velocity) on the basis of the Bernoulli energy law and the interaction with the inertance of the vocal tract. As to sustained modal phonation, calculations are presented for the two possible shapes of glottal duct: convergent and divergent, including absolute calibration in order to obtain quantitative physical values. Whatever the glottal duct configuration, the calculations based on measured values of glottal area and air flow show that the integrated intraglottal pressure during the opening phase systematically exceeds that during the closing phase, which is the basic condition for sustaining vocal fold oscillation. The key point is that the airflow curve is skewed to the right relative to the glottal area curve. The skewing results from air compressibility and vocal tract inertance. The intraglottal pressure becomes negative during the closing phase. As to the soft (or physiological) voice onset, a similar approach shows that the integrated pressure differences (opening phase - closing phase) actually increase as the onset progresses, and this applies to the results based on Bernoulli's energy law as well as to those based on the interaction with the inertance of the vocal tract. Furthermore and similarly, the phase lead of the pressure wave with respect to the glottal opening progressively increases. The underlying explanation lies in the progressively increasing skewing of the airflow curve to the right with respect to the glottal area curve.

Speech Therapy as Treatment for Supragastric Belching.

The purpose of this study was to describe a newly developed speech therapy program as an innovating therapeutic approach and to assess the results of this intervention in patients with supragastric belching. This is a retrospective analysis of prospectively gathered data from 73 patients with supragastric belching who were treated with speech therapy between 2007 and 2017. Of these, 48 were included for evaluation of therapy. Thirty patients had supragastric belching proven by 24-h impedance measurements. Eighteen patients were diagnosed by an experienced speech language pathologist as having supragastric belching according to precise criteria. Speech therapy consists of explanation, creating awareness of esophageal air influx and exercises to discontinue the supragastric belching mechanism. Therapy effect was measured by comparing visual analogue scale (VAS) scores on belching and related symptoms. The median symptom duration at the start of therapy was 2 years. Supragastric belching symptoms decreased significantly with a total median VAS score of 406 (291-463) prior to treatment and a median VAS score of 125 (17-197) following treatment. Forty patients (83%) had a sufficient to major result with a median therapy duration of 3 months and ten sessions. Speech therapy was an effective treatment in the majority of patients with supragastric belching.

Dynamics of the Driving Force During the Normal Vocal Fold Vibration Cycle.

Intraglottal pressure is the driving force of vocal fold vibration. Theoretically, simultaneous quantification of glottal area and transglottal airflow allows the calculation of the intraglottal pressure waveform during a single vibration cycle. In this study, we show that, by combining photoglottography (transglottal light transmission) and airflow (Rothenberg mask) measurements during sustained vocal emissions in vivo, the intraglottal pressure wave can be approximated in a way similar to what has been done in models. The results confirm in vivo that the intraglottal pressure is systematically larger during the opening phase than during the closing phase, so that over one whole cycle, the driving force performs net positive work, accounting for sustained vocal fold motion. A component of this driving force asymmetry is related to vocal tract inertance, which also accounts for the skewing of the airflow waveform compared with the area waveform. Furthermore, the intraglottal pressure ratio (opening:closing) increases with voicing intensity, reaches a maximum around 76 dB, and significantly decreases at higher intensities. This rise and fall suggests that there is a range of intensity values in which, mechanically, a maximum of the driving force is imparted to the vocal fold mass. This finding could have implications for voice economy in professional speakers.

Maximal Ambient Noise Levels and Type of Voice Material Required for Valid Use of Smartphones in Clinical Voice Research.

PURPOSE: Smartphone technology provides new opportunities for recording standardized voice samples of patients and transmitting the audio files to the voice laboratory. This drastically improves the achievement of baseline designs, used in research on efficiency of voice treatments. However, the basic requirement is the suitability of smartphones for recording and digitizing pathologic voices (mainly characterized by period perturbations and noise) without significant distortion. In a previous article, this was tested using realistic synthesized deviant voice samples (/a:/) with three precisely known levels of jitter and of noise in all combinations. High correlations were found between jitter and noise to harmonics ratio measured in (1) recordings via smartphones, (2) direct microphone recordings, and (3) sound files generated by the synthesizer. In the present work, similar experiments were performed (1) in the presence of increasing levels of ambient noise and (2) using synthetic deviant voice samples (/a:/) as well as synthetic voice material simulating a deviant short voiced utterance (/aiuaiuaiu/). RESULTS: Ambient noise levels up to 50 dBA are acceptable. However, signal processing occurs in some smartphones, and this significantly affects estimates of jitter and noise to harmonics ratio when formant changes are introduced in analogy with running speech. The conclusion is that voice material must provisionally be limited to a sustained /a/.

Multidimensional Assessment of the Effectiveness of Group Voice Therapy.

OBJECTIVE: Group voice therapy has been successfully used in patients with dysphonia, but there is little objectively documented evidence of its effects on voice quality and the self-perception of voice fatigue. The aim of this study was to investigate the effectiveness of group therapy in patients with functional dysphonia and minor anatomic vocal fold pathologies linked by appearance and history to voice use in an objective and multidimensional manner. STUDY DESIGN: This is a prospective longitudinal study. METHODS: Before and after treatment, 34 adult women underwent perceptual voice assessments using the grade of dysphonia, roughness, breathiness, asthenia, and strain (GRBAS) scale, Evaluation Vocale Assistée (EVA) system aerodynamic and acoustic assessments, and maximum phonation time measurements, and made subjective evaluations using the Voice Handicap Index. The pretreatment baseline values of the participants were obtained by means of two examinations separated by an interval of 1 week. The parameters belonging to each main dimension were clustered by means of Z-transformation, and the corresponding Z-scores were analyzed. RESULTS: Group therapy was associated with a statistically significant improvement in the perceptual (P = 0.008), acoustic (P = 0.040), aerodynamic (P = 0.009 and <0.001), and self-evaluation parameters (P = 0.011). CONCLUSIONS: Our findings provide evidence that group voice therapy can be associated with improvements in perceptual, acoustic, aerodynamic, and self-evaluated parameters in some patients with dysphonia. Controlled, randomized studies are needed in follow-up. This method of treatment may be a means of reducing the costs and waiting lists associated with rehabilitative treatment, and enhancing patients' motivation and compliance.

A retrospective evaluation of the etiology of unilateral vocal fold paralysis over the last 25 years.

Previous studies have shown that the etiology of laryngeal paralysis has changed over the last decades, with an increase in the incidence of cases attributable to thyroid surgery. The aim of this study was to evaluate longitudinal changes in the etiology of unilateral vocal fold paralysis (UVFP) in a single institution over the last 25 years. This retrospective study analyzed the etiology of UVFP between 1990 and 2015 by comparing a cohort of patients treated in 1990-1992 with a cohort treated in 2013-2015. The final analysis was based on data concerning 356 patients (38.8 % males; mean age 55.3 ± 20.4 years): 113 in the 1990-1992 cohort, and 243 in the 2013-2015 cohort. The main cause of UVFP in the population as a whole was thyroidectomy (41.3 %), followed by an idiopathic origin (25.3 %) and thoracic surgery (12.1 %); this was confirmed in both intra-group analyses. There was a statistically significant association between etiology and the sub-group periods: the prevalence of post-thyroidectomy UVFP was highly significantly lower in the 2013-2015 cohort (35.4 vs 54.0 %), and the prevalence of idiopathic cases was higher (28.4 vs 18.6 %). Etiology significantly related to gender in both cohorts (p value ≤0.001). In the 2013-2015 cohort, there was also a statistically significant relationship between etiology and age classes (p value 0.017), and the left side was more frequently affected than the right (67.1 vs 32.9 %). Our findings document changes in the etiological pattern of UVFP over the last 25 years, with a considerable decrease in post-thyroidectomy UVFP, and a growing predominance of idiopathic and post-thoracic surgery UVFP.

Physiology and Acoustics of Inspiratory Phonation.

INTRODUCTION: Inspiratory phonation (IP) means phonating with inspiratory airflow. Some vocalists remarkably master this technique, to such an extent that it offers new dramatic, aesthetic, and functional possibilities in singing specific contemporary music. The present study aims to a better understanding of the physiological backgrounds of IP. MATERIAL AND METHODS: A total of 51 inhaling utterances were compared with 61 exhaling utterances in a professional soprano highly skilled in inhaling singing, by means of high-speed single-line scanning and advanced acoustic analysis. Ranges of intensity and Fo were kept similar. RESULTS: The main differences are: (1) an inversion of the mucosal wave, (2) a smaller closed quotient in IP, (3) a larger opening/closing quotient in IP with the additional difference that in IP, the quotient is larger than 1 (opening slower than closing), whereas it is less than 1 in expiratory mode (opening faster than closing), (4) a larger vocal-fold excursion in IP, (5) higher values of adaptive normalized noise energy in IP, and (6) a steeper slope of harmonic peaks in IP. However, jitter values are similar (within normal range), as well as damping ratios and central formant frequencies. The two voicing modes cannot be differentiated by blind listening. CONCLUSION: The basic physiological mechanisms are comparable in both voicing modes, although with specific differences. IP is actually to be considered as an "extended vocal technique," a term applied to vocalization in art music, which falls outside of traditional classical singing styles, but with remarkable possibilities in skilled vocalists.

Voice dosimetry and monitoring, with emphasis on professional voice diseases: Critical review and framework for future research.

Professional voice has become an important issue in the field of occupational health. Similarly, voice diseases related to occupations gain interest in insurance medicine, particularly within the frame of specific insurance systems for occupational diseases. Technological developments have made possible dosimetry of voice loading in the work-place, as well as long-term monitoring of relevant voice parameters during professional activities. A critical review is given, with focus on the specificity of occupational voice use and on the point of view of insurance medicine. Remaining questions and suggestions for future research are proposed.

Automatic Assessment of Acoustic Parameters of the Singing Voice: Application to Professional Western Operatic and Jazz Singers.

INTRODUCTION: The obvious perceptual differences between various singing styles like Western operatic and jazz rely on specific dissimilarities in vocal technique. The present study focuses on differences in vibrato acoustics and in singer's formant as analyzed by a novel software tool, named BioVoice, based on robust high-resolution and adaptive techniques that have proven its validity on synthetic voice signals. MATERIAL AND METHODS: A total of 48 professional singers were investigated (29 females; 19 males; 29 Western operatic; and 19 jazz). They were asked to sing "a cappella," but with artistic expression, a well-known musical phrase from Gershwin's Porgy and Bess, in their own style: either operatic or jazz. A specific sustained note was extracted for detailed vibrato analysis. Beside rate (s(-1)) and extent (cents), duration (seconds) and regularity were computed. Two new concepts are introduced: vibrato jitter and vibrato shimmer, by analogy with the traditional jitter and shimmer of voice signals. For the singer's formant, on the same sustained tone, the ratio of the acoustic energy in formants 1-2 to the energy in formants 3, 4, and 5 was automatically computed, providing a quality ratio (QR). RESULTS: Vibrato rates did not differ among groups. Extent was significantly larger in operatic singers, particularly females. Vibrato jitter and vibrato shimmer were significantly smaller in operatic singers. Duration of vibrato was also significantly longer in operatic singers. QR was significantly lower in male operatic singers. CONCLUSIONS: Some vibrato characteristics (extent, regularity, and duration) very clearly differentiate the Western operatic singing style from the jazz singing style. The singer's formant is typical of male operatic singers. The new software tool is well suited to provide useful feedback in a pedagogical context.

Multidimensional assessment of strongly irregular voices such as in substitution voicing and spasmodic dysphonia: a compilation of own research.

This article is a compilation of own research performed during the European COoperation in Science and Technology (COST) action 2103: 'Advance Voice Function Assessment', an initiative of voice and speech processing teams consisting of physicists, engineers, and clinicians. This manuscript concerns analyzing largely irregular voicing types, namely substitution voicing (SV) and adductor spasmodic dysphonia (AdSD). A specific perceptual rating scale (IINFVo) was developed, and the Auditory Model Based Pitch Extractor (AMPEX), a piece of software that automatically analyses running speech and generates pitch values in background noise, was applied. The IINFVo perceptual rating scale has been shown to be useful in evaluating SV. The analysis of strongly irregular voices stimulated a modification of the European Laryngological Society's assessment protocol which was originally designed for the common types of (less severe) dysphonia. Acoustic analysis with AMPEX demonstrates that the most informative features are, for SV, the voicing-related acoustic features and, for AdSD, the perturbation measures. Poor correlations between self-assessment and acoustic and perceptual dimensions in the assessment of highly irregular voices argue for a multidimensional approach.

Automated tracking of quantitative parameters from single line scanning of vocal folds: a case study of the 'messa di voce' exercise.

This article presents a novel application of the 'single line scanning' of the vocal fold vibrations (kymography) in singing pedagogy, particularly in a specific technical voice exercise: the 'messa di voce'. It aims at giving the singer relevant and valid short-term feedback. A user-friendly automatic analysis program makes possible a precise, immediate quantification of the essential physiological parameters characterizing the changes in glottal impedance, concomitant with the progressive increase and decrease of the lung pressure. The data provided by the program show a strong correlation with the hand-made measurements. Additional measurements such as subglottic pressure and flow glottography by inverse filtering can be meaningfully correlated with the data obtained from the kymographic images.

Exploring the sensitivity of speech-in-noise tests for noise-induced hearing loss.

OBJECTIVE: Recently, the digit triplet test was shown to be a sensitive speech-in-noise test for early high-frequency hearing loss in noise-exposed workers. This study investigates if a further improvement is achieved when using a closed set of consonant-vowel-consonant (CVC) speech items with the same vowel, and/or a low-pass (LP) filtered version of the standard speech-shaped noise. DESIGN: Speech reception thresholds in noise were gathered for the digit triplet, CVC, and CVC_LP test and compared to the high-frequency pure-tone average (PTA). STUDY SAMPLE: 118 noise-exposed workers showing a wide range of high-frequency hearing losses. RESULTS: For the 84 Dutch-speaking participants, the CVC test showed an increased measurement error and a decreased between-subject variation, leading to a weaker correlation with the PTA2,3,4,6 (R = 0.64) and thus a lower sensitivity compared to the digit triplet test (R = 0.86). However, the use of LP-filtered noise resulted in a sensitivity improvement (R = 0.79 versus R = 0.64) due to the large increase in between-subject spread. Similar trends were found for the 34 French-speaking workers. CONCLUSIONS: Using CVC words with the same vowel could not increase the sensitivity to detect isolated high-frequency hearing loss. With LP-filtered noise, test sensitivity improved, but it did not surpass the original digit triplet test.