An acoustic study of Cantonese alaryngeal speech in different speaking conditions.

Esophageal (ES) speech, tracheoesophageal (TE) speech, and the electrolarynx (EL) are common methods of communication following the removal of the larynx. Our recent study demonstrated that intelligibility may increase for Cantonese alaryngeal speakers using clear speech (CS) compared to their everyday "habitual speech" (HS), but the reasoning is still unclear [Hui, Cox, Huang, Chen, and Ng (2022). Folia Phoniatr. Logop. 74, 103-111]. The purpose of this study was to assess the acoustic characteristics of vowels and tones produced by Cantonese alaryngeal speakers using HS and CS. Thirty-one alaryngeal speakers (9 EL, 10 ES, and 12 TE speakers) read The North Wind and the Sun passage in HS and CS. Vowel formants, vowel space area (VSA), speaking rate, pitch, and intensity were examined, and their relationship to intelligibility were evaluated. Statistical models suggest that larger VSAs significantly improved intelligibility, but slower speaking rate did not. Vowel and tonal contrasts did not differ between HS and CS for all three groups, but the amount of information encoded in fundamental frequency and intensity differences between high and low tones positively correlated with intelligibility for TE and ES groups, respectively. Continued research is needed to understand the effects of different speaking conditions toward improving acoustic and perceptual characteristics of Cantonese alaryngeal speech.

Is visual gaze in children with autism spectrum disorder related to sequence of emotion intensity presentation? An eye-tracking study of natural emotion perception processes.

Emotion cognitive remediation is a critical component of social skills training for children with autism spectrum disorder (ASD). Visual perception of emotions is highly correlated with the intensity and sequence of presented emotions. However, few studies examined the effect of presentation sequence and intensity on emotion perception. The present study examined the gaze patterns of children with ASD in receiving different sequences of emotion presentation using eye-tracking technologies. Gaze patterns of ecologically-valid video clips of silent emotion stimuli by 51 ASD children and 34 typically developing (TD) children were recorded. Results indicated that ASD and TD children showed opposite visual fixation during different intensity presentation modes: children with ASD showed better emotion perception with a weak-to-strong emotion sequence when presented. The visual reductions in emotion perception in children with ASD may due to different perceptual threshold to emotional intensity. The extent of the reductions could be related to an individual's Personal-Social ability. The present study supports the importance of intensity of emotions and the order at which the emotional stimuli were presented in yielding better emotion perceptions in children with ASD, suggesting that the order of emotion presentation may potentially influence emotion processing during ASD rehabilitation. It is anticipated that the present findings could bring more insights to clinicians for intervention planning in the future.

Transcranial direct current stimulation over the primary motor cortex improves speech production in post-stroke dysarthric speakers: A randomized pilot study.

PURPOSE: The current study investigated the therapeutic potential of transcranial direct current stimulation (tDCS) on speech intelligibility, speech-related physiological and vocal functions among post-stroke dysarthric patients. METHOD: Nine chronic post-stroke dysarthric patients were randomly assigned to the stimulation or sham group. The stimulation group received 2mA of anodal tDCS over the left inferior primary motor cortex for 15 minutes, while the sham group received 30s of stimulation under the same settings. All the participants received 10 daily 15 minutes of individualized speech therapy targeting their dominant phonological process or phonemes with the greatest difficulty. The outcome measures included (1) perceptual analysis of single words, passage reading and diadochokinetic rate, (2) acoustic analysis of a sustained vowel, and (3) kinematic analysis of rapid syllable repetitions and syllable production in sentence, conducted before and after the treatment. RESULTS: The results revealed that both the stimulation and sham groups had improved perceptual speech intelligibility at the word level, reduced short rushes of speech during passage reading, improved rate during alternating motion rate, AMR-kha1, and improved articulatory kinematics in AMR-tha1 and syllables /tha1/ and /kha1/ production in sentence. Compared to the sham group, the stimulation group showed significant improvement in articulatory kinematics in AMR-kha1 and syllable /kha1/ production in sentence. The findings also showed that anodal stimulation led to reduced shimmer value in sustained vowel /a/ phonation, positive changes in articulatory kinematics in AMR-tha1 and syllables /pha1/ and /kha1/ production in sentence at the post treatment measure. In addition to positive effects on articulatory control, reduced perturbation of voice amplitude documented in the stimulation group post treatment suggests possible tDCS effects on the vocal function. CONCLUSIONS: The current study documented the beneficial effects of anodal tDCS over the primary motor cortex on speech production and suggested that combined tDCS and speech therapy may promote recovery from post-stroke dysarthria.

Acoustic characteristics associated with liquid swallowing sounds of different bolus consistencies in young healthy adults.

BACKGROUND: Cervical auscultation has been used clinically as an augmentative procedure for swallow examination. Despite its frequent use for screening and preliminary assessment of swallowing, the usefulness of cervical auscultation is controversial due to a lack of sufficient research, particularly in quantifying swallowing sounds. AIMS: To document the acoustic characteristics of normal swallowing sound associated with swallowing bolus of different consistencies among younger healthy adults. METHODS & PROCEDURES: A total of 30 healthy young adult participants swallowed 5 ml thickened liquids of four different consistencies (slightly thick, mildly thick, moderately thick and extremely thick) prepared using a starch-based commercial thickener, and the corresponding swallowing sounds were recorded using a wireless accelerometric stethoscope. An array of acoustic measures including duration of swallowing sound (DSS), duration to peak intensity (DPI), frequency at peak intensity (FPI), peak intensity (PI), average intensity (AI), and difference between peak and average intensity (DPAI) values associated with the swallowing signals were obtained. OUTCOMES & RESULTS: In general, increased durational measures of the swallowing sounds were associated with an increase in bolus consistency. Intensity measures including PI, AI and DPAI were found to be stable across different consistencies. The change in FPI did not appear to be particularly meaningful due to its high variability. In addition, no significant differences were observed between men and women. CONCLUSIONS & IMPLICATIONS: Swallow sounds associated with different bolus consistencies could be quantified and used to differentiate consistencies. The present findings could serve as a reference for future swallowing research of normal and dysphagic population. WHAT THIS PAPER ADDS: What is already known on the subject Cervical auscultation using traditional stethoscope has been used as part of an informal clinical swallow examination by practitioners. Validity of cervical auscultation is controversial, possibly due to the lack of normative data on swallow sounds. What this paper adds to existing knowledge The present study explored the possibility of using wireless accelerometric stethoscopy for cervical auscultation for dysphagia screening. Acoustic profiles of swallow sounds associated with boluses of different consistencies in healthy individuals were examined. What are the potential or actual clinical implications of this work? Findings contribute to our knowledge about the acoustic characteristics of swallow sounds of boluses of different consistencies in healthy young individuals. The study provides normative clinical data on cervical auscultation using wireless accelerometric stethoscope for normal swallow.

How Accurate Are the Consistency Labels Used in Hong Kong? An Objective Study of the Consistency of Thickened Liquids Using International Dysphagia Diet Standardisation Initiative and Consistometric Measurements.

OBJECTIVES: The present study objectively examined the consistency (thickness) of labels that are used in Hong Kong for the population with dysphagia using an International Dysphagia Diet Standardisation Initiative (IDDSI) flow test and Bostwick consistometric measurements. METHODS: Liquids were prepared by thickening water to achieve 4 consistency labels (slightly thick, mildly thick, medium thick, and extra thick) according to manufacturer's instructions, employing 2 types of thickening products that are used in Hong Kong, i.e., starch based and gum based. For each consistency label prepared using each thickening product, the IDDSI flow test and consistometric measurements were obtained and compared. RESULTS: The results showed that the actual thickness of liquids was highly dependent on the type of thickener (starch based vs. gum based) used. Thickened liquids prepared using the starch-based thickener were generally thinner than the actual value at a lower concentration. CONCLUSION: Though prepared strictly following the manufacturer's instructions, the thickened liquids fail to faithfully correlate with the standardized norms established according to the IDDSI framework and the objective consistometric measurement using a Bostwick consistometer. Therefore, caution must be exercised when administering a thickened diet following the manufacturer's instructions for patients with dysphagia.

Cultural Adaptation and Validation of Speech Handicap Index: A Scoping Review.

Objectives The Speech Handicap Index (SHI) is a self-reported speech-related quality of life assessment originally developed for measuring the psychosocial speech impact in patients with oral or pharyngeal cancer. This review article provides a scoping review of the literature on the validated SHI, with the purpose of identifying and documenting available studies and procedures for the cultural adaption and validation of SHI. Method Prime databases including PubMed, EMBASE, and Google Scholar were searched for journal publications reporting validation of the SHI. Reviews and reference cross-checking were performed using a priori selection criteria. A body of literature related to SHI was scoped and publication quality was categorized independently by two investigators. After applying all the screening criteria, articles that met the eligibility criteria were included in the review. Results The scoping review yielded 10 articles that met the inclusion criteria presenting the SHI in eight different languages, including Dutch, U.K. English, French, Korean, Simplified Chinese (Mandarin), Lithuanian, Italian, and European Portuguese. All of them reported validity, reliability, and translation method. Discussion and Conclusions High reliability and validity between various language versions of the SHI were identified. The current scoping review provides a useful summary and could be a helpful precursor to a systematic review on SHI in the future. Supplemental Material https://doi.org/10.23641/asha.14082704.

Effect of total laryngectomy on vowel production: An acoustic study of vowels produced by alaryngeal speakers of Cantonese.

Purpose: To investigate the effect of total laryngectomy on vowel production, the present study examined the change in vowel articulation associated with different types of alaryngeal speech in comparison with laryngeal speech using novel derived formant metrics.Method: Six metrics derived from the first two formants (F1 and F2) including the First and Second Formant Range Ratios (F1RR and F2RR), triangular and pentagonal Vowel Space Area (tVSA and pVSA), Formant Centralisation Ratio (FCR) and Average Vowel Spacing (AVS) were measured from vowels (/i, y, ɛ, a, ɔ, œ, u/) produced by oesophageal (ES), tracheoesophageal (TE), electrolaryngeal (EL), pneumatic artificial laryngeal (PA) speakers, as well as laryngeal speakers.Result: Data revealed a general reduction in articulatory range and a tendency of vowel centralisation in Cantonese alaryngeal speakers. Significant articulatory difference was found for PA and EL compared with ES, TE, and laryngeal speakers.Conclusion: The discrepant results among alaryngeal speakers may be related to the difference in new sound source (external vs internal). Sensitivity and correlation analyses confirmed the use of the matrix of derived formant metrics provided a more comprehensive profile of the articulatory pattern in the alaryngeal population.

The use of the Lombard Effect in Improving Alaryngeal Speech.

OBJECTIVE: The present study examined and compared the Lombard effect among laryngeal and alaryngeal speakers including esophageal, tracheoesophageal, pneumatic artificial laryngeal, electrolaryngeal speakers of Cantonese. The subsequent change in intelligibility was also examined. METHODS: A total of 52 native Cantonese-speaking laryngeal and alaryngeal speakers (10 laryngeal , 8 laryngeal , 13 electrolaryngeal , 11 esophageal, and 10 tracheoesophageal) participated in a reading task involving three 10-syllable Cantonese sentences under 10 background conditions: quiet, 60 dB, 65 dB, 70 dB, 75 dB, 80 dB, 85 dB, 90 dB, 95 dB, and 100 dB white background noise. Speech intelligibility associated with speaking conditions were evaluated by five naïve Cantonese speakers. RESULTS: Output intensity was significantly increased in all speaker types under all nine noisy background conditions when compared with the quiet condition. However, the amount of increase was different for different modes of phonation. In addition, significant difference in speech intelligibility between laryngeal and alaryngeal speakers was found at all conditions, but not among any alaryngeal speech. DISCUSSION AND CONCLUSION: The Lombard reflex is still present after total laryngectomy. Yet, different alaryngeal speech was associated with different amount of loudness change, and subsequent improvement in intelligibility was not observed.

The Characteristics of Intelligence Profile and Eye Gaze in Facial Emotion Recognition in Mild and Moderate Preschoolers With Autism Spectrum Disorder.

Childhood autism spectrum disorder (ASD) can easily be misdiagnosed, due to the nonspecific social and communicational deficits associated with the disorder. The present study attempted to profile the mental development and visual attention toward emotion among preschool children with mild or moderate ASD who were attending mainstream kindergartens. A total of 21 children (17 boys and 4 girls) diagnosed with mild or moderate ASD selected from 5,178 kindergarteners from the Xi'an city were recruited. Another group of 21 typically developing (TD) children who were matched with age, gender, and class served as controls. All children were assessed using the Griffiths Mental Development Scales-Chinese (GDS-C), and their social visual attention was assessed during watching 20 ecologically valid film scenes by using eye tracking technique. The results showed that ASD children had lower mental development scores in the Locomotor, Personal-Social, Language, Performance, and Practical Reasoning subscales than the TD peers. Moreover, deficits in recognizing emotions from facial expressions based on naturalistic scene stimuli with voice were found for ASD children. The deficits were significantly correlated with their ability in social interaction and development quotient in ASD group. ASD children showed atypical eye-gaze pattern when compared to TD children during facial emotion expression task. Children with ASD had reduced visual attention to facial emotion expression, especially for the eye region. The findings confirmed the deficits of ASD children in real life multimodal of emotion recognition, and their atypical eye-gaze pattern for emotion recognition. Parents and teachers of children with mild or moderate ASD should make informed educational decisions according to their level of mental development. In addition, eye tracking technique might clinically help provide evidence diagnosing children with mild or moderate ASD.

The Lombard effect associated with Chinese male alaryngeal speech.

Objective: Alaryngeal speech shows marked reduction in vocal intensity, resulting in reduced intelligibility. Lombard effect, speaking with background noise has been found to boost speakers' intensity. The study investigated oesophageal (ES), tracheoesophageal (TE) and electrolaryngeal (EL) speech production under quiet and noisy background conditions to determine if the Lombard effect is still present after laryngectomy.Method: Fifteen laryngeal and thirty-seven alaryngeal speakers who were native speakers of Cantonese were recruited and instructed to read aloud a Cantonese passage under two background conditions: quiet and 100 dB background noise conditions.Result: Significant increase in vocal intensity was found in all speaker types under the noise condition. In addition, perceived intelligibility ratings provided by naïve Cantonese listeners revealed that the overall intelligibility under noise was improved for TE and laryngeal speakers, but not for ES and EL speakers, when compared with quiet condition.Discussion and conclusion: Results confirmed that the Lombard effect is still present after total laryngectomy. However, intelligibility may not always be improved with increased vocal loudness. Improved intelligibility was only observed for TE and laryngeal speakers, but not ES and EL speakers. Clinical implications for the use of the Lombard effect in post-laryngectomy speech rehabilitation are discussed.

Effects of transcranial direct current stimulation over the Broca's area on tongue twister production.

PURPOSE: The present study aimed to explore the short-term effect of anodal transcranial direct current stimulation (tDCS) on tongue twister production. METHOD: Thirty healthy native Cantonese adult speakers were randomly assigned to the anodal tDCS group or the sham tDCS group. Anodal tDCS of 2 mA was applied over the Broca's area of the brain. The stimulation lasted for 20 min for the anodal tDCS group and 30 s for the sham tDCS group. The participants were instructed to produce a list of tongue twisters before, immediately after and 4 h after tDCS. RESULT: Speech rate and response accuracy measured immediately after stimulation were significantly faster and higher, respectively, than before stimulation. Although there was no change in speech rate measured at 4 h after stimulation, response accuracy at that time point was significantly lower than that measured immediately after stimulation. However, there were no significant differences between the anodal tDCS and sham tDCS groups in either speech rate or response accuracy. CONCLUSION: The findings revealed that a single session of anodal tDCS over the Broca's area did not significantly improve speech production during tongue twister production.

Articulatory Contact Pressure during Bilabial Plosive Production in Esophageal and Tracheoesophageal Speech.

OBJECTIVES: The present study investigated the articulatory contact pressure during the production of bilabial plosives by esophageal (ES), tracheoesophageal (TE), and laryngeal speakers. METHODS: The peak contact pressure (PCP) during bilabial plosive production of /CVCVCVCVCV/ syllable strings of /p/ and /ph/ was obtained from 10 ES, 10 TE, and 10 laryngeal speakers of Cantonese. PCP values were obtained by using a pressure transduction system (Iowa Oral Performance Instrument) during speech production. RESULTS: The results showed that ES speakers exhibited a significantly greater PCP value than TE and laryngeal speakers, as revealed by cheek muscle compression force. In addition, the unaspirated bilabial plosive /p/ was associated with a greater PCP than its aspirated counterpart /ph/. CONCLUSION: The current findings might support the hypothesis of over-exaggerated speech for better intelligibility among alaryngeal speakers. In addition, the increased oral muscular effort could be associated with a compensatory strategy for maintaining a high intraoral pressure or the unique air intake by ES speakers.

Effect of Temporal Lobe Epilepsy on Auditory-motor Integration for Vocal Pitch Regulation: Evidence from Brain Functional Network Analysis.

Temporal lobe epilepsy (TLE) is a medically refractory focal epilepsy associated with structural deficits. Considerable evidence has revealed that patients with TLE also exhibit deficits in functional connectivity. According to previous research, patients with TLE exhibited decreased performance in speech sound perception and auditory-motor integration for voice control, which might be related to the compromised brain network connectivity. However, the specific nature of functional connectivity within and across brain regions remains largely unknown. To answer this question, we extended previous research from examining the topological properties of the entire brain network to the intra- and inter-regional communications of different brain regions. Patients with TLE and healthy controls were recruited to perform a pitch reflex task, during which electroencephalograph (EEG) data were acquired to construct graphical brain networks. Compared with healthy controls, inter-regional and cross-hemispheric connections were reduced in patients with TLE, whose functional networks were primarily composed of intra-regional connections. Significant differences in network parameters (betweenness centrality, modularity, and functional integration) as well as network hubs between the two groups further supported our findings that TLE is associated with alterations in functional connectivity during auditory-motor integration.

A Volumetric Analysis of the Vocal Tract Associated with Laryngectomees Using Acoustic Reflection Technology.

OBJECTIVE: Previous studies of the laryngectomized vocal tract using formant frequencies reported contradictory findings. Imagining studies of the vocal tract in alaryngeal speakers are limited due to the possible radiation effect as well as the cost and time associated with the studies. The present study examined the vocal tract configuration of laryngectomized individuals using acoustic reflection technology. SUBJECTS AND METHODS: Thirty alaryngeal and 30 laryngeal male speakers of Cantonese participated in the study. A pharyngometer was used to obtain volumetric information of the vocal tract. All speakers were instructed to imitate the production of /a/ when the length and volume information of the oral cavity, pharyngeal cavity, and the entire vocal tract were obtained. The data of alaryngeal and laryngeal speakers were compared. RESULTS: Pharyngometric measurements revealed no significant difference in the vocal tract dimensions between laryngeal and alaryngeal speakers. CONCLUSION: Despite the removal of the larynx and a possible alteration in the pharyngeal cavity during total laryngectomy, the vocal tract configuration (length and volume) in laryngectomized individuals was not significantly different from laryngeal speakers. It is suggested that other factors might have affected formant measures in previous studies.

Voice onset time of alveolar stop /t/ and realization of unaspirated affricates associated with Mandarin-speaking children with repaired cleft palate.

PURPOSE: To examine perceptually the realization of unaspirated affricates and voice onset time (VOT) features of /t/ in Mandarin-speaking children with repaired cleft palate, and to explore the difficulties associated with unaspirated affricate production from the perspective of the VOT of /t/. METHOD: Twenty-three children with repaired cleft palate and 22 age-matched typical native Mandarin speakers were recruited. Speakers with cleft palate were allocated into two groups based on expert perceptual judgment of nasality: one group with perceived normal resonance (PNR) (n = 14, average age = 9.3 years), and another group with perceived hypernasal resonance (PHR) (n = 9, average age = 10.3 years). INTERVENTION: Stimuli were collected through a series of picture naming tasks, targeting the production of initial consonants /t/ and three unaspirated Mandarin affricates /ts, tʂ, tɕ/. The productions of each affricate were evaluated by two experienced speech therapists. The VOT of /t/ was measured using PRAAT speech analysis software. RESULT: The majority of unaspirated affricates were omitted and/or weakly realized by the group of PHR speakers, but not for the PNR group. A significantly smaller mean VOT value associated with /t/ was identified for the PHR group, as compared to the PNR group. A group difference for VOT value was not found between the PNR group and the typical control group. CONCLUSION: The voicing features of /t/ and omitted/weak realization of unaspirated affricates identified in the PHR group indicated that the deviant production of unaspirated affricates in the cleft palate group could be associated with the voicing characteristics of the alveolar stop /t/, and this merits further investigation.

Spectral moment analysis of affricates produced by Mandarin-speaking pre-adolescents with repaired cleft palate.

OBJECTIVE: To explore the spectral differences in frication noise between aspirated and unaspirated affricates in typical Putonghua (standard Mandarin Chinese) pre-adolescent speakers, and to compare the spectral characteristics of affricate production between speakers with repaired cleft palate and their non-cleft peers. PARTICIPANTS AND INTERVENTION: Spectral moment analysis, a quantitative approach to capture the contour of speech spectra, was carried out on speech samples produced by two groups of speakers: (a) speakers with repaired cleft palate (n=14, mean age=11.7 years) and (b) typical speakers (n=10, mean age=11.0 years). RESULTS: Data from typical speakers showed that the unaspirated affricates had significantly higher first spectral moment (M1) than their aspirated counterparts. Compared with typical speakers, individuals with repaired cleft palate exhibited a lower first moment for the four affricates /ts, tʂ, tɕ(h), tɕ/. CONCLUSION: The results revealed important acoustical differences between aspirated and unaspirated affricates for typical speakers. The trend of spectral deviation may have contributed to the difficulty in producing unaspirated affricates found in Putonghua-speaking individuals with speech disorders related to cleft palate.

Consonant accuracy in Mandarin-speaking children with repaired cleft palate.

OBJECTIVE: To compare the consonant production of Chinese-speaking cleft palate children with perceived hypernasal resonance (PHR) after palatoplasty and those with perceived normal resonance (PNR), and to assess the possible influence of language on articulation. SETTING: Two hospital cleft lip and palate centers in mainland China. PARTICIPANTS: Thirty-one speakers were allocated into two groups based on perceptual judgment results of their resonance provided by three speech therapists: one group with PNR (n=20, average age=9.3 years), and another group with PHR (n=11, average age=8.3 years). All participants had no known hearing or cognitive deficits. INTERVENTION: Articulation was evaluated using two Mandarin Chinese assessment tools, the Putonghua Segmental Phonology Test and the Deep Test for Cleft Palate Speakers in Putonghua. Speaker consonant accuracy was evaluated by two experienced speech therapists. RESULTS: Compared to individuals with PNR, the PHR group exhibited more difficulties on production of unaspirated consonants, including/b/,/t/,/k/,/ts/,/tʂ/ and/tɕ/, than for aspirated consonants. CONCLUSION: The distinctive feature of aspiration in Mandarin phonology brought a language specific pattern to consonant production among those speakers with PHR after primary palatal closure.

Designing, implementing and evaluating an online problem-based learning (PBL) environment--a pilot study.

Problem-based learning (PBL) has been shown to be effective for promoting student competencies in self-directed and collaborative learning, critical thinking, self-reflection and tackling novel situations. However, the need for face-to-face interactions at the same place and time severely limits the potential of traditional PBL. The requirements of space and for meeting at a specific location at the same time create timetabling difficulties. Such limitations need to be tackled before all potentials of PBL learning can be realized. The present study aimed at designing and implementing an online PBL environment for undergraduate speech/language pathology students, and assessing the associated pedagogical effectiveness. A group of eight PBL students were randomly selected to participate in the study. They underwent 4 weeks of online PBL using Adobe Connect. Upon completion of the experiment, they were assessed via a self-reported questionnaire and quantitative comparison with traditional PBL students based on the same written assignment. The questionnaire revealed that all participating students enjoyed online PBL, without any perceived negative effects on learning. Online PBL unanimously saved the students travel time to and from school. Statistical analysis indicated no significant difference in assignment grades between the online and traditional PBL groups, indicating that online PBL learning appears to be similarly effective as traditional face-to-face PBL learning.

Vocal tract dimensional characteristics of professional male and female singers with different types of singing voices.

The present study examined the possible relationship between classification of professional singing voices and their vocal tract parameters including vocal tract length and volume, and vowel formant frequencies. Acoustic reflection technology (ART) was used to measure vocal tract length and volume of 107 professional singers: 32 tenors, 25 baritones, 27 sopranos, and 23 mezzo-sopranos. The first three formant frequencies (F1-F3) of the English vowels /a, æ, i/ produced by the professional singers were also obtained. Results indicated significantly shorter oral and vocal tract length, and smaller oral and vocal tract volume associated with sopranos when compared with mezzo-sopranos. Acoustically, sopranos had higher F1, F2, and F3 values than mezzo-sopranos. The present findings suggest that, in addition to vocal tract length, vocal tract volume may also affect formant frequencies, implying the possibility that classifying professional singing voices is based on both vocal tract length and volume information.

Nonlinear dynamical analysis of laryngeal, esophageal, and tracheoesophageal speech of Cantonese.

Esophageal (SE) and tracheoesophageal (TE) speech are the most commonly used alaryngeal voicing types after total laryngectomy-a surgical procedure of removing a pathological larynx. Both SE and TE voices show more aperiodicity than normal laryngeal (NL) voices, and the vocal characteristics of alaryngeal voices are notoriously difficult to extract. The present study investigated the difference in vocal characteristics among NL, SE, and TE voices using perception measures and nonlinear dynamical analysis. Correlation dimension (D(2)) and sample entropy (SampEn) were obtained from 90 voice samples produced by 10 TE, 10 SE, and 10 NL male Cantonese speakers. Correlation between nonlinear dynamical parameters and perceptual ratings of different voices was also examined. Results show that both D(2) and SampEn values were significantly higher for TE and SE voices than NL voice. The overall perceptual judgment of SE and TE voice quality was negatively correlated with D(2) and SampEn. This finding supports the validity of using nonlinear dynamical parameters in assessing voice quality. Results of the present study also indicate that nonlinear dynamical analysis could be a supplemental tool to traditional acoustic analysis, especially for analyzing the voice quality of alaryngeal speech.