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

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

The Relation Between Endoscopic and Subjective Laryngopharyngeal Reflux Signs, Vocal Tract Discomfort, Voice Handicap, and Voice Disorder Type: Same Yet Different?

OBJECTIVES: This study aimed to investigate the relation between subjective voice-related symptoms and endoscopic findings in patients with different etiology of voice disorder and vocally healthy subjects with and without laryngopharyngeal reflux (LPR). STUDY DESIGN: Retrospective cross-sectional study. METHODS: The study involved 149 participants (106 female, 43 male) including 125 with various voice disorders (functional, structural, and neurogenic) and 24 vocally healthy individuals. For self-rating the German versions of the Voice Handicap Index (VHI), Vocal Tract Discomfort (VTD) Scale, and Reflux Symptom Index (RSI) were applied, while endoscopic evaluations utilized the Reflux Finding Score (RFS) and Reflux Sign Assessment (RSA). Statistical analyses incorporated ANOVA with Bonferroni posthoc tests to identify group variations. Correlations between VTD Scale, VHI, RSI, RFS, and RSA were evaluated using Pearson's correlation coefficient. To examine test sensitivity and specificity for the VTD Scale and RSA, we performed a receiver operating characteristics analysis. Youden's-Index was applied to determine the cut-off-value with best discriminatory abilities. The diagnosis of LPR was assumed when the criteria of RFS > 7 AND RSI > 13 was met. RESULTS: Significant differences for all voice diagnosis groups and vocally healthy individuals for RFS and all three self-rating questionnaires were found. Moreover, there was significant correlation between VTD Scale and VHI and RSI as well as RSI and RFS, which was moderate, negative in the group of persons with LPR. However, there was no significant difference for RSA results between the vocally healthy or any diagnosis group. CONCLUSION: Thus, the RFS may be more suitable to predict reflux and voice-related symptoms. The VTD Scale is a useful instrument in screening voice disorders but also LPR and can therefore be used as a tool for decision-making when transferring to a specialist.

High and Wide: An In Silico Investigation of Frequency, Intensity, and Vibrato Effects on Widely Applied Acoustic Voice Perturbation and Noise Measures.

OBJECTIVES: This in silico study explored the effects of a wide range of fundamental frequency (fo), source-spectrum tilt (SST), and vibrato extent (VE) on commonly used frequency and amplitude perturbation and noise measures. METHOD: Using 53 synthesized tones produced in Madde, the effects of stepwise increases in fo, intensity (modeled by decreasing SST), and VE on the PRAAT parameters jitter % (local), relative average perturbation (RAP) %, shimmer % (local), amplitude perturbation quotient 3 (APQ3) %, and harmonics-to-noise ratio (HNR) dB were investigated. A secondary experiment was conducted to determine whether any fo effects on jitter, RAP, shimmer, APQ3, and HNR were stable. A total of 10 sinewaves were synthesized in Sopran from 100 to 1000 Hz using formant frequencies for /a/, /i/, and /u/-like vowels, respectively. All effects were statistically assessed with Kendall's tau-b and partial correlation. RESULTS: Increasing fo resulted in an overall increase in jitter, RAP, shimmer, and APQ3 values, respectively (P < 0.01). Oscillations of the data across the explored fo range were observed in all measurement outputs. In the Sopran tests, the oscillatory pattern seen in the Madde fo condition remained and showed differences between vowel conditions. Increasing intensity (decreasing SST) led to reduced pitch and amplitude perturbation and HNR (P < 0.05). Increasing VE led to lower HNR and an almost linear increase of all other measures (P < 0.05). CONCLUSION: These novel data offer a controlled demonstration for the behavior of jitter (local) %, RAP %, shimmer (local) %, APQ3 %, and HNR (dB) when varying fo, SST, and VE in synthesized tones. Since humans will vary in all of these aspects in spoken language and vowel phonation, researchers should take potential resonance-harmonics type effects into account when comparing intersubject or preintervention and postintervention data using these measures.

Differences and Reliability of Linear and Nonlinear Acoustic Measures as a Function of Vocal Intensity in Individuals With Voice Disorders.

PURPOSE: Linear acoustic indices are significantly influenced by speaking voice intensity. The main aim of this work was to compare acoustic measures based on linear and nonlinear models in different speaking voice intensity levels and to analyze the reliability of those measures in different intensity levels in subjects with voice disorders. METHODS: 435 samples from subjects (314 women, 121 men with a mean age of 41.07 ± 13.73) diagnosed with various voice disorders were used. In total, 17 acoustic measures were derived from the vowel /ɛ/ sustained at three intensity levels (soft, comfortable, and loud). Five were linear (standard deviation of the fundamental frequency (f0), jitter, shimmer, harmonics-to-noise ratio (HNR) and smoothed cepstral peak prominence (CPPS)), and twelve were nonlinear measures, namely correlation dimension (D2), correlation entropy (H2), first minimum of the mutual information function (FMMI), relative entropy (ENTR-R), largest Lyapunov exponent (Lyap), determinism (DET), transitivity, mean diagonal line length (Lmed), Shannon entropy (ENTR-S), mean length of vertical structures, also known as trapping time (TT), laminarity (LAM) and recurrence period density entropy (RPDE). Differences between speaking voice intensity levels were assessed by Friedman's test and Nemenyi as posthoc test. Intraclass correlation coefficient was used to investigate if each acoustic measure remains in agreement (reliability) between different voice intensity levels. RESULTS: There were significant differences in all acoustic measures about vocal intensity level (P < 0.001). Intraclass correlation coefficient was very good for HNR (>0.61) and good for Lyap, DET, ENTR-S, Lmed, RPDE, and TT (0.41-0.60). CONCLUSIONS: All acoustic measures varied as a function of vocal intensity in voice disordered adults, while this relation was different for linear and nonlinear measures. Only the measures HNR, Lyap, DET, ENTR-S, Lmed, RPDE and TT had an acceptable reliability between different voice intensity levels. Therefore, patient`s voice SPL should be controlled or indicated during acoustic vocal assessment.

Cross-Validation and Normative Values for the German Vocal Tract Discomfort Scale.

Purpose The Vocal Tract Discomfort Scale (VTD Scale) is a self-rating questionnaire investigating physical symptoms in the larynx associated with vocal pathology. The aim of this work was to investigate the reliability, validity, sensitivity, and specificity of the first German version and to provide normative data with thresholds for pathology and a scaling scheme. Study Design A retrospective multicenter study was performed. Method A total of 571 participants (409 female and 162 male), with a mean age of 47.2 years, were recruited at three German centers; of these, there were 447 participants with voice disorder and 124 vocally healthy participants. The clinical examination consisted of patient history, visual laryngeal examination, acoustic and aerodynamic assessment, perceptual analysis by the Grading-Roughness-Breathiness-Asthenia-Strain Scale, and subjective evaluation using the VTD Scale and the Voice Handicap Index (VHI). Statistics included group comparisons (t test and analysis of variance), Pearson correlation coefficient (between VTD Scale and VHI), and Cronbach's alpha to assess validity and reliability. Analysis of receiver operating characteristics was performed to examine VTD Scale's discriminatory ability and provide a cutoff score. Additionally, percentiles were applied to provide VTD Scale ranges. Results There were highly significant differences between healthy participants and participants with voice disorder regarding the total score and both subscales of the VTD Scale. Internal consistency was excellent (α = .928). We found moderate, positive correlation between the VTD Scale and VHI (ρ = .596, p < .001). Receiver operating characteristics analysis showed an area under the curve of 0.876 (p < .001, 95% confidence interval [0.846, 0.906]). VTD Scale ranges were no (score: 0-13), mild (score: 14-26), moderate (score: 27-40), and severe (score: 41-96) disorder. Conclusions Results confirm an excellent reliability and validity of the German VTD Scale. It provides additional and independent diagnostic information and is a useful instrument to complement voice assessment. The scaling into four severity subgroups allows the tool to be used for screening patients and considers a transferral to a voice specialist.

Effects of Vocal Intensity and Fundamental Frequency on Cepstral Peak Prominence in Patients with Voice Disorders and Vocally Healthy Controls.

OBJECTIVE: Cepstrum-based voice measures, such as smoothed cepstral peak prominence (CPPS), are influenced by voice sound pressure level (SPL) in vocally healthy adults. Since it is unclear if similar effects hold in voice disordered adults and how these interact with natural fundamental frequency (fo) changes, this study examines voice SPL and fo effects on CPPS in women with vocal hyperfunction and vocally healthy controls. STUDY DESIGN: Retrospective matched case-control study. METHODS: Fifty-eight women with vocal hyperfunction were individually matched with 58 vocally healthy women for occupation and approximate age. The patient group comprised women exhibiting phonotraumatic vocal hyperfunction associated with vocal fold nodules (n = 39) or polyps (n = 5), and nonphonotraumatic vocal hyperfunction associated with primary muscle tension dysphonia (n = 14). All participants sustained the vowel /a/ at soft, comfortable, and loud loudness conditions. Voice SPL, fo, and CPPS (dB) were computed from acoustic voice recordings using Praat. The effects of loudness condition, measured voice SPL, and fo on CPPS were assessed with linear mixed models. Pairwise correlations among voice SPL, fo, and CPPS were assessed using multiple regression analysis. RESULTS: Increasing voice SPL correlated significantly (P < 0.001) with higher CPPS in both patient (r2 = 0.53) and normative groups (r2 = 0.45). fo had statistically significant effects on CPPS (P < 0.001), but with a weak relation for the patient (r2 = 0.02) and control groups (r2 = 0.05). CONCLUSIONS: In women with and without voice disorder, CPPS is highly affected by the individual's voice SPL in vowel phonation. Future studies could investigate how these effects should be controlled for to improve the diagnostic value of acoustic-based cepstral measures.

Fundamental Frequency and Intensity Effects on Cepstral Measures in Vowels from Connected Speech of Speakers with Voice Disorders.

OBJECTIVE: Cepstral peak prominence (CPP) and smoothed CPP (CPPS) have been described as reliable parameters to detect overall dysphonia in standardized connected speech samples. Recent studies indicate that vocal intensity (sound pressure level, SPL) and fundamental frequency (fo) changes may influence cepstral measurement results in healthy speakers. The main aim of the present work was to investigate the effects of prosody related SPL and fo variations on cepstral measures in speech of adults with voice disorders. STUDY DESIGN: Retrospective cross-sectional study. METHODS: Recordings of CAPE-V sentences from 27 voice disordered Brazilian Portuguese speakers (19 women, eight men) with a mean age of 45 years (SD = 13) were investigated. Five /a/ vowels were manually extracted from stressed syllables in different positions. Voice fo (Hz), SPL (dBA), CPP (dB), and CPPS (dB) were computed using PRAAT. Statistical analysis included Linear Mixed Models with ANCOVA and Bonferroni post hoc tests. RESULTS: Voice SPL as single factor and combined with fo had a highly significant effect (P ≤ 0.001), while fo alone had no significant impact on both CPP and CPPS (P ≥ 0.77). Voice fo, SPL, CPP, and CPPS of the first vowel were all significantly lower than of the last vowel (P ≤ 0.03). CONCLUSION: In vowel samples from connected speech of adults with voice disorders, we observed better CPP and CPPS in higher voice SPL alone and combined with higher fo. Further, the vowel position influenced the present results. A larger clinical study should confirm how prosody related SPL and fo and vowel position effects could be controlled for in connected speech samples.

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.

Relationship Between Laryngeal Signs and Symptoms, Acoustic Measures, and Quality of Life in Finnish Primary and Kindergarten School Teachers.

OBJECTIVE: This study investigated the relationship between the acoustic measure smoothed cepstral peak prominence (CPPS), teacher's quality of life as measured by the voice activity and participation profile (VAPP), laryngeal signs and symptoms, voice related health problems and laryngoscopic findings in Finnish teachers. The relationship between CPPS and sound pressure level (SPL) was also assessed. METHODS: Vowel and text samples from 183 healthy Finnish teachers (99 kindergarten teachers [KT] and 84 primary school teachers [PST]) were analyzed for CPPS. Text reading was recorded in conversational loudness by PST, and KT were recorded wearing headphones, while listening to a masking noise of children talking to simulate their classroom voice and environment. CPPS values were correlated with the VAPP, self-reported laryngeal signs and symptoms, voice related health variables, and laryngoscopic findings. RESULTS: There was a significant difference between the two groups for CPPS text, PST showed significantly lower CPPS values (10.44) than KT (11.52). There was no difference between the two groups for CPPS vowel phonation. There was a significant correlation between SPL text and CPPS text for KT (P < 0.001, r = 0.43) but not for PST (P < 0.10, r = 0.16). There was a significant correlation between SPL vowel and CPPS vowel for both PST (P < 0.001, r = 0.47) and KT (P < 0.001, r = 0.45). CPPS did not correlate with the VAPP, laryngeal signs and symptoms, health variables or laryngeal findings. Factorial analysis of variance resulted in a significant relationship between the VAPP, laryngeal signs and symptoms, and teacher type. Teacher type and symptoms had a significant effect on VAPP scores. CONCLUSIONS: In the present work CPPS does not correlate with vocal health indicators of functionally healthy teachers. CPPS was significantly influenced by differences in speaking voice SPL, emphasizing the impact of recording conditions and technique. There was a significant relationship between laryngeal signs and symptoms, teacher type and the VAPP. Laryngeal signs and symptoms and teacher type are important variables and should be included in the clinical evaluation of occupational voice users, and voice problems.

Cervical Spine Disability in Correlation with Subjective Voice Handicap in Patients With Voice Disorders: A Retrospective Analysis.

OBJECTIVE: Neck muscle dysfunction has been considered as risk factor or consequence of voice disorders. This study investigates the correlation between neck and voice-related subjective symptoms in patients with voice disorders. STUDY DESIGN: Retrospective case-control study. METHODS: 100 adult patients (59 female and 41 male) over 18 years with a mean age of 50.01 years (SD 16, range 24-87), of which 68 were under 60 years, were included. 50 patients had organic voice pathologies and 50 functional dysphonia. Outcome measures were the Voice Handicap Index 9 international (VHI-9i) and the Neck Disability Index (NDI-G). Spearman rank order coefficient was applied to determine the correlation between overall and single item VHI and NDI results. Subanalyses were done for functional vs. organic disorder, gender and age ± 60 years. RESULTS: Mean overall VHI-9i (13.93, SD = 7.81, range = 0-31) and mean NDI-G (6.07, SD = 7.71, range = 0-43) showed a significant mild correlation (rs = 0.220, P = 0.02). Split into subgroups the relation was stronger in patients with organic pathologies (rs = 0.297, P = 0.03), but not significant in functional disorders (r = 0.148, P = 0.30). There was a moderate relation in men (rs = 0.317, P = 0.04). Single item correlation was highest between VHI-9i item P4 (physiological) and NDI-G item reading (cognitive functioning) (rs = 0.480, P = 0.002). CONCLUSION: Specifically patients with organic voice disorders showed increased voice symptoms with the presence of neck dysfunction. This indicates a risk for a functional imbalance of the muscles surrounding the larynx, which in extreme cases may hinder functional voice rehabilitation even after phonosurgery. Therefore, neck dysfunction should be considered in voice diagnostics.

Do Standard Instrumental Acoustic, Perceptual, and Subjective Voice Outcomes Indicate Therapy Success in Patients With Functional Dysphonia?

OBJECTIVES: The validity and sensitivity to change of instrumental acoustic measurements in patients with functional dysphonia have been controversially discussed. This work examines combined voice therapy effects on standard acoustic measurements, and if these agree with perceptual and subjective voice outcomes. STUDY DESIGN: Retrospective study. METHODS: Thirty-nine patients (26 women, 13 men) aged 20-70 years (mean: 46.3, standard deviation 12.8) with functional dysphonia were investigated before and after combined voice therapy. Instrumental parameters included mean and range of speaking fundamental frequency (fo) and intensity (SPL (dBA)); maximum SPL and mean fo of calling voice; minimum, maximum, range of singing voice fo and SPL, jitter (%), and the Dysphonia Severity Index. Voice Handicap Index-9 international was used for subjective and Grading-Roughness-Breathiness-Asthenia-Strain scale for perceptual assessment. Differences were investigated by Wilcoxon signed ranks test and coherences by Spearman rank correlation coefficient. RESULTS: After treatment, the speaking voice fo range (7-8.13 semitones) and SPL range (12.9-14.85 dB(A)) were significantly larger (P < 0.05). Both parameters were highly correlated (P < 0.001). Subjective symptoms were significantly reduced from a mean Voice Handicap Index-9 international of 15.6-8.6, and all perceptual Grading-Roughness-Breathiness-Asthenia-Strain scale parameters were significantly improved (G: 1.05-0.51) after therapy (P < 0.05). These findings were not associated with any acoustic parameter (P > 0.05). CONCLUSIONS: Significantly improved subjective and perceptual findings verify positive combined voice therapy effects in patients with functional dysphonia. The larger fo and SPL speaking voice range after treatment indicate an altered voice technique. These instrumental measures may be clinical indicators of therapy success and transfer effects.

Transcultural Adaptation and Validation of the German Version of the Vocal Tract Discomfort Scale.

OBJECTIVES: Currently, there is no standardized German questionnaire to assess vocal tract discomfort in voice patients. The aim of this study was to evaluate the internal consistency, reliability, and validity of the German version of the Vocal Tract Discomfort (VTD) Scale. STUDY DESIGN: This is a cross-sectional study. METHODS: First, a cross-cultural translation and adaptation from English to German was performed. One hundred seven patients between the ages of 18 and 76 with voice disorders were divided into two different diagnosis-related groups (organic and functional voice disorder) and 50 vocally healthy adults were included. All participants completed the VTD Scale and the Voice Handicap Index (VHI). The internal consistency of the VTD Scale was analyzed through Cronbach's α coefficient. Pearson correlation between the VDT Scale and VHI total scores was used to determine criterion validity. The VDT Scale score differences related to diagnosis groups were assessed with analysis of variance. RESULTS: Excellent internal consistency was found (α = 0.919, P < 0.05), and criterion validity was confirmed by a high correlation between the total VTD Scale and VHI (r = 0.674). There was a significant difference between the diagnosis groups' total VTD Scale score (F[4.135] = 15.114, P = 0.000). Furthermore, the vocally healthy adults had significantly lower values than the two diagnosis groups (x¯: 11.48, s = 8.340). CONCLUSIONS: The German version of the VTD Scale has an excellent internal consistency and reliability, and shows high clinical validity. Thus, it is a useful instrument in voice diagnostics.

Reliable acoustic measurements in children between 5;0 and 9;11 years: Gender, age, height and weight effects on fundamental frequency, jitter and shimmer in phonations without and with controlled voice SPL.

BACKGROUND: Current pediatric voice assessment guidelines include instrumental measurements of fundamental frequency (F0) and the perturbation indices jitter and shimmer. In children below 10 years, gender, age, height and weight effects on these parameters have been inconsistently characterized. Recent research in healthy children showed, that differences in habitual speaking voice intensity (voice SPL) under the usual assessment procedure significantly affect jitter and shimmer. These effects were reduced in phonations with controlled voice SPL >80dBA. Reliable measurement methods and description of physiologic influencing factors are essential to identify pathologic voices. OBJECTIVE: This cross-sectional single cohort study investigates in children between 5;0 and 9;11 years how gender, age, height and weight affect voice F0, jitter and shimmer in phonations at individually "medium" voice intensity (modeling the usual clinical practice) and with controlled voice SPL >80dBA. SUBJECTS AND METHODS: 68 vocally healthy children (39 f/29 m) aged 5;0-9;11 years provided 3 prolonged phonations of/a/at individually "medium" and controlled voice intensity at ">80dBA" (visual feedback, 10cm distance). F0 (Hz), jitter (%), shimmer (%) and voice SPL (dBA) were determined with PRAAT. Gender, age, height and weight effects without and with controlled voice SPL were assessed by descriptive statistics, Analysis of Variance and Linear Mixed Models. RESULTS: F0 (Hz), jitter (%), shimmer (%) and voice SPL (dBA) were significantly different in medium voice compared to >80dBA (p<0.01). In medium phonations girls had a higher F0 than boys (girls: 276.7(50.7), boys: 261.5(33.7)), but with >80dBA this difference was only minimal (girls: 328.9(52.2), boys 327.9(51.2)). Mean jitter (0.27(0.10)) and shimmer (4.34(1.68)) were smaller and showed less spread (jitter: 0.5(0.26); shimmer: 9.47(3.47)) with >80dBA. Gender, age, height and weight had no significant effects on F0, jitter, shimmer and voice SPL in both phonation types (p-range=0.42-0.99). CONCLUSIONS: Neither without nor with controlled voice SPL there were systematic gender, age, height or weight effects on voice F0, jitter and shimmer. Gender related F0 discrepancies were equalized in phonations with >80dBA. In children below 10 years gender related acoustic voice differences may be mainly linked to behavior, which should be considered in future works regarding physiologic voice development.

Clinical relevance of speaking voice intensity effects on acoustic jitter and shimmer in children between 5;0 and 9;11 years.

BACKGROUND: Current voice assessment recommendations for dysphonic children comprise instrumental acoustic measurements of the perturbation parameters jitter and shimmer. In healthy adults and children changes in speaking voice sound pressure level (voice SPL) have significant confounding effects on both parameters. In adults these effects were considerably reduced in phonations with controlled voice SPL >80dBA (10cm distance). However, it is unclear if these findings apply to children and if children are able to control for their own voice intensity. OBJECTIVE: This cross-sectional single cohort study investigates voice SPL effects on jitter and shimmer in children between 5;0 and 9;11 years phonating at individually "medium" (modeling "comfortable" loudness of the usual clinical protocol), "soft" and "loud" voice and a prescribed intensity level of ">80dBA" (10cm distance, with visual control). Further both their ability to phonate at a prescribed voice intensity level and the effect on SPL related confounding effects were studied. SUBJECTS AND METHODS: A total of 68 healthy children (39 f/29m) aged 5;0 to 9;11 years were included. All phonated the vowel/a/for 5s, three times at four defined voice intensity levels (soft/medium/loud/>80dBA) each. Jitter (%), shimmer (%) and voice SPL (dBA) were determined using PRAAT. Voice intensity level effects were assessed by descriptive statistics, Analysis of Variance (ANOVA) and Linear Mixed Models (LMM). RESULTS: There were significant differences for jitter and shimmer between all voice tasks (p<.01). Jitter and shimmer were lowest and showed the smallest spread in controlled phonations ">80dBA". 19 children below 7;0 years could not perform the voice tasks and were excluded from the study. CONCLUSIONS: This practical study demonstrated a significant effect of voice loudness and task on jitter and shimmer in children. Since the observed confounding effects were large compared to treatment effects, jitter and shimmer may not be meaningful without adequate control of voice SPL. In phonations at ">80dBA" (10cm distance) voice SPL related effects were considerably reduced. However, this assessment protocol was suitable only for children above 7;0 years. Application of this task to future studies of dysphonic children may yield clinically valuable information.

Routine acoustic voice analysis: time to think again?

PURPOSE OF REVIEW: This paper reviews recent evidence regarding the validity and reliability of acoustic voice analysis in routine clinical assessments. The current role of jitter and shimmer, the most-used indices, and how their clinical application might be improved are evaluated. RECENT FINDINGS: Even though the evidence is limited, acoustic analysis is widely used to assist differential diagnosis, documentation and evaluation of treatment for clinical voice disorders. Recent clinical data have not shown that jitter and shimmer are absolute or independent indices of voice pathology or perceptual hoarseness. However, in pretreatment and posttreatment comparisons within patients, acoustic analysis might have value as an outcome measure.Yet, the true value of clinical acoustic analysis might be masked by the confounding effects due to assessment system, gender, vowel and especially speaking voice intensity. SUMMARY: The validity of acoustic assessments in clinical applications remains unproven. Measurement reliability is still limited and might be greatly improved with relatively simple changes and consensus in measurement protocols and techniques. For instance, clinical assessment procedures and current normative values would have to be revised considering gender and vowel. Thus, future research might establish the validity and potential of clinical acoustic assessments.