Vocal Intensity Research Articles

Impact of Instructed Laryngeal Manipulation on Acoustic Measures of Voice–Preliminary Results

Control of laryngeal muscles is required to manipulate pitch, volume, and voice quality. False vocal fold activity (FVFA) refers to the constriction and release of constriction of the false vocal folds. True vocal fold mass (TVFM) represents the cross-sectional thickness of the vocal folds. Larynx height (LH) refers to the vertical position of the larynx in the neck. To date, studies of voice control have examined the effects of these parameters separately. No study has investigated the impact of instructed systematic manipulation of these parameters on acoustic voice measures in vocally healthy trained subjects. This study examined the effects of systematically manipulating FVFA, TVFM, and LH on several acoustic voice measures. Twelve vocally trained speakers were instructed to use specific techniques to achieve experimental conditions of constriction and release of constriction of FVFA, thicker and thinner TVFM, and normal and low LH. Each condition was implemented in combination with manipulating the other parameters. Voice recordings of sustained vowel /a/ and Rainbow Passage were obtained for all laryngeal manipulation conditions and underwent acoustic analyses for fundamental frequency (F0), signal typing, harmonics-to-noise ratio (HNR), cepstral peak prominence (CPP), and vocal relative intensity. Constricted FVFA caused more aperiodicity in the signals, lower CPP, and lower vocal relative intensity than release of constriction. Thicker TVFM resulted in significantly higher CPP and vocal relative intensity than thinner TVFM. Modifying TVFM did not affect F0 and HNR. Low LH had significantly lower F0 but did not impact on HNR, CPP, and intensity. The effects of systematic manipulation of each laryngeal parameter resulted in independent acoustic effects without measurable interaction. Release of constriction of FVFA, thicker TVFM, and low LH were configurations that resulted in more optimal acoustic signals.

Maximum vocal intensity as a primary outcome measure in unilateral vocal fold paralysis patients.

To evaluate voice intensity as the primary outcome measurement when treating unilateral vocal fold paralysis patients. This prospective observational study comprised 34 newly diagnosed unilateral vocal fold paralysis patients undergoing surgical interventions: injection laryngoplasty or medialisation thyroplasty. Voice assessments, including maximum vocal intensity and other acoustic parameters, were performed at baseline and at one and three months post-intervention. Maximum vocal intensity was also repeated within two weeks before any surgical interventions were performed. The results were compared between different time points and between the two intervention groups. Maximum vocal intensity showed high internal consistency. Statistically significant improvements were seen in maximum vocal intensity, Voice Handicap Index-10 and other acoustic analyses at one and three months post-intervention. A significant moderate negative correlation was demonstrated between maximum vocal intensity and Voice Handicap Index-10, shimmer and jitter. There were no significant differences in voice outcomes between injection laryngoplasty and medialisation thyroplasty patients at any time point. Maximum vocal intensity can be applied as a treatment outcome measure in unilateral vocal fold paralysis patients; it can demonstrate the effectiveness of treatment and moderately correlates with self-reported outcome measures.

Real-time feedback control of voice in cochlear implant recipients.

ObjectivesTo evaluate feedback‐dependent vocal control in cochlear implant patients using pitch‐shifted auditory feedback.MethodsTwenty‐three CI recipients with at least 6 months of implant experience were enrolled. Vocal recordings were performed while subjects repeated the vowel /e/ and vocal signals were altered in real‐time using a digital effects processor to introduce a pitch‐shift, presented back to subjects using headphones. Recordings were analyzed to determine pitch changes following the pitch‐shifted feedback, and results compared to the magnitude of the shift as well as patient demographics.ResultsConsistent with previous results, CI patients' voices had higher pitches with their implant turned off, a change explainable by increases in vocal loudness without the CI. CI patients rapidly compensated for pitch‐shifted feedback by changing their vocal pitch, but only for larger shifts. Considerable inter‐subject variability was present, and weakly correlated with the duration of implant experience and implant sound thresholds.ConclusionsCI patients, like normal hearing individuals, are capable of real‐time feedback‐dependent control of their vocal pitch. However, CI patients are less sensitive to small feedback changes, possibly a result of courser CI frequency precision, and may explain poorer than normal vocal control in these patients.Level of EvidenceLevel 3b.

The Effect of Pitch and Loudness Auditory Feedback Perturbations on Vocal Quality During Sustained Phonation

Dysphonia is a reduction in vocal quality that impacts communication and is often an early sign of a voice disorder. There is little information regarding the effects of auditory feedback control of loudness and pitch on voice quality. In this study, we used both loudness-shift and pitch-shift paradigms to study the relationship between auditory feedback control and vocal quality as measured by smoothed cepstral peak prominence (CPPS), which reflects the harmonicity of the voice signal. Experimental, mixed design. We applied 200 ms loudness-shifts (± 0, 3, or 6 dB) and pitch-shifts (± 0, 50, and 100 cents) to auditory feedback during sustained vowel production in 25 healthy adults. We then measured CPPS before and after the loudness-shift or pitch-shift to investigate the effect of changes in auditory feedback on vocal harmonicity. Results showed that, on average, CPPS significantly decreased between the first half of the measured segment and the last half of the segment in the absence of auditory feedback shifts, suggesting that voice quality may be reduced across longer vowels over time. Upward and downward shifts in loudness auditory feedback caused a relative increase in CPPS, indicating an improvement in vocal harmonicity, even in cases when vocal intensity was reduced. Pitch alterations had inconsistent and minimal effects. We propose that there may be a control mechanism for voice quality that increases harmonicity of the voice signal to improve voice audibility (ie, ability to be heard) in the presence of unpredictable variability in voice intensity.

Multiparametric laryngeal assessment of the effect of thalamic deep brain stimulation on essential vocal tremor

ObjectiveEVT is a refractory voice disorder that significantly affects quality of life. This work aims to conduct a multiparametric assessment of the effect of deep brain stimulation (DBS) of the thalamic ventral intermediate nucleus (VIM) on essential vocal tremor (EVT) and investigate the relation between DBS lead location and EVT outcomes. MethodsNine participants underwent DBS for essential tremor and were diagnosed with co-occurring EVT in this prospective cohort study. Objective measurements including acoustic evaluation of vocal fundamental frequency (F0) and intensity modulation and subjective measurements including physiologic evaluation of the oscillatory movement of the laryngeal muscles and vocal tract and perceptual ratings of tremor severity were collected PRE and POST DBS. Finally, we investigated the relation between DBS lead location and EVT outcomes. ResultsAcoustic modulations of F0 and intensity were significantly improved POST DBS. Physiologic assessment showed a POST DBS reduction of oscillatory movement in the laryngeal muscles and vocal tract, but not significantly. Listener and participant perception, of EVT severity was also significantly reduced. Finally, our results indicate better EVT control with increased distance to midline of left VIM thalamic stimulation. ConclusionsBy employing a battery of objective and subjective measures, our study supports the benefit of DBS for the treatment of EVT and specifies the acoustic and physiologic mechanisms that mediate its positive effect. We further provide preliminary results on the relation between lead location and EVT outcomes, laying the foundation for future studies to clarify the optimal DBS target for the treatment of EVT.

Consecuencias laringoscópicas, electroglotográficas, acústicas y sintomatológicas producidas por la sobrecarga vocal en mujeres con voces sanas y no entrenadas

La sobrecarga es una de las etapas del continuo de carga vocal. Actualmente, se considera que su investigación permite una mejor comprensión de la patología y sintomatología funcional de la voz. El objetivo de este trabajo fue analizar las consecuencias laringoscópicas, electroglotográficas, acústicas y sintomatológicas producidas por la sobrecarga vocal en mujeres con voces sanas y no entrenadas. Se examinó el comportamiento acústico, laringoscópico, electroglotográfico y sintomatológico de 30 mujeres que se sometieron a una tarea de sobrecarga vocal caracterizada por la lectura ininterrumpida de un texto durante 60 minutos, cuya intensidad fluctuó entre los 75 y 85 dB. A nivel laringoscópico, se observó mayor vascularización, aumento de la compresión supraglótica y cambios en la amplitud, simetría y onda mucosa. Acústicamente, se evidenció incremento significativo en la frecuencia fundamental e intensidad vocal. En la electroglotografía, el cociente de cierre y la fase abierta y cerrada disminuyeron significativamente, mientras que a nivel sintomatológico, la totalidad de la muestra expresó al menos un síntoma de fatiga vocal. En conclusión, los hallazgos observados son expresiones de la fatiga del mecanismo tiroaritenoideo y de la inflamación aguda de la cubierta cordal.

Lee Silverman Voice Treatment for dysarthria in patients with Parkinson's disease: a systematic review and meta-analysis.

Approximately 89% of patients with Parkinson's disease (PD) suffer from dysarthria. Lee Silverman Voice Treatment (LSVT), a behavioral therapy, aims to improve speech and voice functions. The objective was to assess the effectiveness of LSVT compared with other/no speech interventions for dysarthria in patients with PD. Electronic databases, including PubMed, Embase and the Cochrane Library, were searched. The publication date of all included studies was before 6 March 2020. Only randomized controlled trials (RCTs) that evaluated the LSVT intervention compared with other/no speech intervention were considered. The data obtained from the included studies were described and the mean differences were calculated. Eight RCTs were included in this meta-analysis comparing LSVT with other/no speech interventions. In the comparison of LSVT versus no intervention, vocal intensity for sustained 'Ah' phonation, reading the 'Rainbow passage', monologue and describing a picture increased by 8.87, 4.34, 3.25 and 3.31dB, respectively, after 1month of therapy. Compared with the respiratory therapy group, the LSVT group also showed significant improvement in vocal intensity for sustained 'Ah' phonation, reading the 'Rainbow passage' and monologue immediately after treatment (13.39, 6.66 and 3.19dB). Positive improvement still existed after 24months. There was no difference in the therapeutic effect between face-to-face and online LSVT. The effectiveness of LSVT for dysarthria in patients with PD was verified in these trials. However, future RCTs with sufficient participants are essential to evaluate the effectiveness of LSVT for dysarthria.

The Impact of Communication Modality on Voice Production.

Purpose Communicating remotely using audio and audiovisual technology is ubiquitous in modern work and social environments. Remote communication is increasing in medicine and in voice therapy delivery, and this evolution may have an impact on speakers' voices. This study sought to determine whether these communication modalities impact the voice production of typical speakers. Method The speech acoustics of 12 participants with healthy voices were recorded as they held standardized conversations with a single investigator using three communication modalities: in-person, remote-audio, and remote-audiovisual. Participants rated their vocal effort on a 100-mm visual analog scale. Results Compared to in-person communication, self-ratings of vocal effort were statistically significantly increased for remote-audiovisual communication; vocal effort during remote-audio and in-person communication were not significantly different. In comparison to in-person communication, vocal intensity and smoothed cepstral peak prominence (CPPS) were statistically significantly higher during remote-audio and remote-audiovisual communication. Effect sizes for CPPS changes were larger than for sound pressure level (SPL), and changes in CPPS and SPL between in-person and remote-audiovisual communication were not significantly correlated. Conclusions Vocal effort and SPL were increased when using remote-audio and remote-audiovisual communication in comparison to in-person communication. Voice quality was also impacted by technology use, with changes in CPPS that were consistent with, but not fully explained by, increases in SPL. This may impact the telepractice delivery of voice therapy, and further investigation is warranted.

Quality of Life and Acoustic Comfort in Educational Environments of Curitiba, Brazil

It is believed that poor classroom acoustics leads to lower levels of student learning and exposes teachers vocal folds to greater physical wear and tear. This study sought to compare the quality of life by World Health Organization (whoqol-bref) questionnaire of 61 teachers working at schools with different acoustic conditions. This paper reports on a descriptive exploratory study aimed at ascertaining the following: (1) outdoor sound pressure levels in the immediate surroundings of two primary schools; (2) background noise levels inside classrooms; (3) reverberation times in classrooms; (4) the teacher's perception of noise in the work environment; (5) the teacher's vocal intensity in the classroom; and (6) the teacher's perceived quality of life. It was found that the quality of life of teachers, as well as the major causes of acoustic discomfort, do not stem from a source outside the classroom, halls, and physical education classes. Instead, they originate inside the classroom and are caused by students during school hours; the teachers' vocal intensity exceeds the limits of tolerability both in schools that provide acoustic comfort and in those that do not. The basic conditions required to ensure the health of the participants in this study during their workday were found to be unsatisfactory.

Changes in the voice production of solo singers across concert halls.

To investigate the influence of room acoustics on singing, four lyrical singers (soprano, mezzo-soprano, tenor, baritone) performed four musical pieces in eight different venues (from dry studio to reverberant church). In addition to vocal intensity measured by a near-field microphone, glottal behavior (vibratory fundamental frequency and contact quotient) was assessed by electroglottography. Statistical linear mixed models showed that the variance in vocal performance was partly explained by room acoustics. Complementary to previous results on voice musical features influenced by timbre and level of the room's response, voice production parameters were mostly influenced by spatial aspects of the room's response.

Feasibility and Acceptability of Lee Silverman Voice Treatment in Progressive Ataxias

Communication difficulties have considerable impact on people with progressive ataxia, yet there are currently no evidence-based treatments. LSVT LOUD® focuses on the production of healthy vocal loudness whilst also improving breath support, vocal quality, loudness and articulation in participating patients. This study aimed to investigate whether Lee Silverman Voice Treatment (LSVT LOUD®) can improve communication effectiveness in these patients. We performed a rater-blinded, single-arm study investigating LSVT LOUD® treatment in a population of patients with progressive ataxia including Friedreich’s ataxia (n = 18), spinocerebellar ataxia type 6 (n = 1), idiopathic cerebellar ataxia (n = 1), and spastic paraplegia 7 (n = 1). Twenty-one patients were recruited to the study, with 19 completing treatment. Sessions were administered via Skype in the LSVT-X format, meaning two sessions per week over a period of 8 weeks. Assessments included two baseline and two post-treatment measures and focused on outcome measures covering aspects ranging from physiological function to impact and participation. Results indicate improvements in patient-perceived outcomes for 14 of the 19 participants, in both speech and psychosocial domains. Speech data furthermore demonstrate significant improvements in prolonged vowel duration, and voice quality measures. Intelligibility and naturalness evaluations showed no change post-treatment. Patients reported high acceptability of the treatment itself, as well as administration by Skype. This is the largest treatment study for people with progressive ataxia published to date. It provides an indication that LSVT LOUD® can have a positive impact on communication in this patient group and could form the basis for larger-scale trials.

Effects of Performance Time of the Voiced High-Frequency Oscillation and Lax Vox Technique in Vocally Healthy Subjects

The primary objective was to analyze and compare the effects of the voiced high-frequency oscillation (VHFO) and Lax Vox techniques in different performance times. The secondary objective was to determine if there were any differences between the exercises in men and women. Thirty volunteers (15 male, 15 female) without vocal complaints or any history of dysphonia participated in this study. The volunteers performed the VHFO and the Lax Vox techniques with a week washout, and the performance times were 1- and 3-minute long with a 15-minute interval. They answered two questionnaires on vocal and laryngopharyngeal symptoms intensity self-assessment and had acoustic measurements (cepstral peak prominence-smoothed - CPPs - , alpha ratio, and L1-L0) obtained, before 1 minute (M0), after 1 minute (M1), and after 3 minutes (M3). They had their sustained vowel /a/ and number counting 1-10 recorded. Data were analyzed by using the repeated measures ANOVA (P < 0.05) and the post hoc Tukey's test. For vowel /a/, men had higher CPPs and lower alpha ratio values. For number counting, men had lower CPPs values, and for both genders there was an improvement after M1, which remained at M3. For the low-pitched voice symptom, men showed a decrease after M1, regardless of the exercise. Men had better results after VHFO, while women had better results after the Lax Vox technique for the tightness symptom. Regardless of exercise or gender, there was a decrease in tickling and irritated throat after M1, but at M3 their intensity tended to increase. The lump in the throat symptom decreased at M1 and remained at the same intensity at M3 regardless of exercise or gender. It is important to be aware of the voice effects and the patient reports when requesting 3 minutes of both exercises. Thus, the conclusion is that the best performance time is 1 minute. For most outcomes, there was no difference between exercises and participants' genders. However, for the low-pitched voice symptom, men benefited more from both exercises, and for tightness, men benefited more from VHFO; in contrast, women benefited more from the Lax Vox technique. Therefore, such gender differences should be considered when choosing these exercises.

Effects of an intensive voice treatment on articulatory function and speech intelligibility in children with motor speech disorders: A phase one study

Producing speech that is clear, audible, and intelligible to others is a challenge for many children with cerebral palsy (CP) and children with Down syndrome (DS). Previous studies have demonstrated the effectiveness of using the Lee Silverman Voice Treatment (LSVT LOUD®) to increase vocal loudness and improve speech intelligibility in individuals with dysarthria secondary to Parkinson’s disease (PD), and some research suggests that it also may be effective for individuals with dysarthria secondary to other conditions, including CP and DS. Although LSVT LOUD targets healthy vocal loudness, there is some evidence of spreading effects to the articulatory system. Acoustic data from two groups of children with secondary motor speech disorders [one with CP (n = 17) and one with DS (n = 9)] who received a full dose of LSVT LOUD and for whom post-treatment intelligibility gains have been previously reported, were analyzed for treatment effects on: 1) vowel duration, 2) acoustic vowel space and 3) the ratio of F2/i/ to F2/u/. Statistically significant changes in vowel duration and acoustic vowel space occurred pre-treatment to 12 weeks post-treatment in the CP group, and increased acoustic vowel space was observed in 5 of the DS participants. The present study provides preliminary evidence of intensive voice treatment spreading effects to the articulatory system in some children with CP and children with DS consistent with previous findings in other populations.

Speech and Language Therapy for Voice Problems in Parkinson's Disease: A Meta-Analysis.

Patients with Parkinson's disease (PD) commonly have speech and voice problems that affect their functional communication and that are not sensitive to pharmacological or neurosurgical treatments. The authors aimed to evaluate the effects of speech and language therapies (SLTs) on dysphonia in patients with PD by analyzing data from published randomized controlled trials (RCTs). Studies in English and Chinese that were related to speech and language treatment for patients with PD were retrieved from PubMed, Embase, Chinese National Knowledge Infrastructure, China Science and Technology Journal Database, Chinese Biomedical Literature Database, and Wanfang Database. On the basis of exclusion criteria, 391 records identified through the search were reduced to 10 studies that included 230 patients in the treatment groups and 205 patients in the control groups. A meta-analysis of data from the 10 studies was performed to examine the effects of SLTs on dysphonia in patients with PD. SLTs increased sound pressure level during sustained phonation, reading of the Rainbow Passage, and monologue 6 months after treatment, enhanced semitone standard deviation during reading of the Rainbow Passage more than 12 months after treatment, and reduced Voice Handicap Index scores among patients with PD with dysphonia problems at least 3 months after treatment. These findings demonstrate the efficacy of SLTs, especially Lee Silverman Voice Treatment, in increasing vocal loudness and functional communication among patients with PD. Further RCTs with large samples and multicenter participation are needed to validate the long-term effects and the efficacy of SLTs among patients with severe PD.

The Effect of Unilateral Hearing Protection on Vocal Intensity With Varying Degrees of Background Noise

The Lombard effect (LE) is a phenomenon in which speakers adjust their vocal production by raising the volume in noisy environments. As a result, the LE can create problems of vocal strain, fatigue and potential injury. This study aims to examine the difference in vocal intensity output in subjects wearing unilateral hearing protection versus no hearing protection in the presence of background noise. Each subject was seated inside a sound booth wearing a head-mounted microphone. Subjects were asked to read an excerpt from "The Rainbow Passage" while various levels of background noise were played: 50, 60, 70, and 80 dBA (Multitalker Babble). Each noise level was played while the subject was with and without unilateral ear protection (Optime 98 Earmuff [3M]) in random order. The earmuff has a noise reduction rating of 25 dB. After each reading of the text, subjects were asked to rate communication disturbance, vocal clarity, and discomfort during talking using a 10 cm visual analogue scale. The LE is reduced from 0.38 dB/dB to 0.29 dB/dB with unilateral ear occlusion. However, self-perception of disturbance, clarity and comfort were not affected by unilateral occlusion, only by noise level. Unilateral hearing protection reduces the LE and may protect against phonotrauma when speaking in an environment with loud background noise.

Effects of Fundamental Frequency, Vocal Intensity, Sample Duration, and Vowel Context in Cepstral and Spectral Measures of Dysphonic Voices.

Purpose Smoothed cepstral peak prominence (CPPS) and harmonics-to-noise ratio (HNR) are acoustic measures related to the periodicity, harmonicity, and noise components of an acoustic signal. To date, there is little evidence about the advantages of CPPS over HNR in voice diagnostics. Recent studies indicate that voice fundamental frequency (F0) and intensity (sound pressure level [SPL]), sample duration (DUR), vowel context (speech vs. sustained phonation), and syllable stress (SS) may influence CPPS and HNR results. The scope of this work was to investigate the effects of voice F0 and SPL, DUR, SS, and token on CPPS and HNR in dysphonic voices. Method In this retrospective study, 27 Brazilian Portuguese speakers with voice disorders were investigated. Recordings of sustained vowels (SVs) /a:/ and manually extracted vowels (EVs) /a/ from Consensus Auditory-Perceptual Evaluation of Voice sentences were acoustically analyzed with the Praat program. Results There was a highly significant effect of F0, SPL, and DUR on both CPPS and HNR (p < .001), whereas SS and vowel context significantly affected CPPS only (p < .05). Higher SPL, F0, and lower DUR were related to higher CPPS and HNR. SVs moderately-to-highly correlated with EVs for CPPS, whereas HNR had few and moderate correlations. In addition, CPPS and HNR highly correlated in SVs and seven EVs (p < .05). Conclusion Speaking prosodic variations of F0, SPL, and DUR influenced both CPPS and HNR measures and led to acoustic differences between sustained and excised vowels, especially in CPPS. Vowel context, prosodic factors, and token type should be controlled for in clinical acoustic voice assessment.

Long term phonatory function following acoustic neuroma surgery: a cohort study

Background: Acoustic neuroma (AN) is a well-recognized cause of neurological morbidity, peripheral facial paralysis being one of the most prevalent. Phonatory dysfunction in the late post-operative term has not been properly addressed so far.Objective: The objective of this study is to describe the outcomes of phonatory function on the long-term follow-up of AN surgery and identify its prognostic factors.Material and methods: This cohort study included patients submitted to AN surgery from 1999 to 2014, with a mean follow up of 6.4 ± 4.5 years. To evaluate the phonatory function, we performed a combination of noninvasive acoustic and aerodynamic measurements including vocal intensity and stability, maximum declination rate of the glottal airflow (MDR) and transglottal pressure scale (TP).Results: 101 patients were studied. 25 (24.7%) presented a deficit in phonatory function. Women comprised 56% and the mean age was 42.4 ± 13.8 years (range19–80). 100% presented reduced expiratory airflow capacity with excessive manifestation of the laryngeal musculature (TP > 1,23s ;MDR/z/<MDR/s/). Dysphonic patients presented more neurofibromatosis II (NF II) (40% vs 12.7% p = .002), large tumors (3.8 ± 1.1 p = .002) and needed less surgeries (≥256.7% vs 74.6%, p = .0073) in univariate analysis. NFII and tumor size were predictive of dysphonia according to multivariate analysis (NFII-OR 5.57, p = .006; tumor size-each 1 cm, OR1.68, p = .062).Conclusion: The late postoperative prevalence of dysphonia corresponded to 24.7%. Dysphonia could be secondary to the hyperfunction of laryngeal musculature explained by the reduced expiratory airflow found in our patients. Tumor size and NF II were predictors for the occurrence of dysphonia in the present study.HighlightsThe comprise of phonation function can be a morbidity of AN surgeryNF II and tumor size were predictive of dysphonia on late postoperative periodData of hypofunction secondary to the phonatory hyperfunction were unanimous in the dysphonic patients.The early diagnosis and treatment of phonation function could avoid alterations of pneumophono-articulatory coordination and projection deficiency.

Artificial sounds following biological rules: A novel approach for non-verbal communication in HRI

Emotionally expressive non-verbal vocalizations can play a major role in human-robot interactions. Humans can assess the intensity and emotional valence of animal vocalizations based on simple acoustic features such as call length and fundamental frequency. These simple encoding rules are suggested to be general across terrestrial vertebrates. To test the degree of this generalizability, our aim was to synthesize a set of artificial sounds by systematically changing the call length and fundamental frequency, and examine how emotional valence and intensity is attributed to them by humans. Based on sine wave sounds, we generated sound samples in seven categories by increasing complexity via incorporating different characteristics of animal vocalizations. We used an online questionnaire to measure the perceived emotional valence and intensity of the sounds in a two-dimensional model of emotions. The results show that sounds with low fundamental frequency and shorter call lengths were considered to have a more positive valence, and samples with high fundamental frequency were rated as more intense across all categories, regardless of the sound complexity. We conclude that applying the basic rules of vocal emotion encoding can be a good starting point for the development of novel non-verbal vocalizations for artificial agents.

The Effect of Single Harmonic Tuning on Vocal Loudness

The study addresses the benefit of tuning single harmonics with vocal tract resonances to increase vocal loudness. The loudness of theoretically constructed vocal sounds with variable levels of sound energy in the first, second, and third harmonics is computed on the basis of ISO standard 226:2003. In comparison to increased loudness with changes in overall spectral slope, it is shown that single harmonic tuning requires a greater range of SPL to produce a similar range of loudness. For example, a 10-40 dB increase in the level of a single harmonic produces less than two doublings of loudness, whereas a spectral slope change from -12 dB/octave to -3 dB/octave can produce a similar doubling of loudness with only a 5 dB SPL increase.

Effect of Resonance Tube Technique on Oropharyngeal Geometry and Voice in Individuals with Parkinson's Disease

To verify the immediate effect of the flexible resonance tube vocal technique on the oropharyngeal geometry and vocal acoustic parameters of individuals with Parkinson's disease (PD) and to study the correlation between oropharyngeal geometry and the intensity and fundamental frequency (f0) parameters of the voice. Forty individuals participated-20 with PD and 20 healthy individuals, with a mean age of 60.95 (± 5.69) years. There were 10 men and 10 women in each group. All underwent pharyngometric analysis of the vocal tract and voice acoustics parameters before and after use of the vocal technique with a flexible resonance tube. After the technique, there was a reduction in pharyngeal cavity volume only in females in the healthy group, a reduction in shimmer values in females in both groups and males in PD group and an improvement in noise parameters in females in the PD group. There was a negative correlation between vocal tract volume and intensity, between f0 and vocal tract volume, between f0 and oropharyngeal junction area, between f0 and oral cavity volume as well as a positive correlation between oral cavity length and f0. The vocal technique with the flexible resonance tube applied to individuals with PD improved the subjects' voice quality in the perceptual and acoustic voice parameters. Regarding the oropharyngeal geometry, it was possible to observe its correlation with the parameters of vocal intensity and frequency in the studied population.