Objective Voice Quality Analysis Before and After Onset of Unilateral Vocal Fold Paralysis

This study was designed to investigate objective voice quality measurements in unilateral vocal fold paralysis (UVFP) by eliminating intersubject variability. To our knowledge this is the first report objectively analyzing paralytic dysphonia as compared to the same voice before onset of UVFP. The voices of two male subjects were prospectively recorded before and after the onset of iatrogenic UVFP (thoracic surgery).The following acoustic measurements of the vowel /a/ were performed using the CSL and MDVP (Kay Elemetrics): jitter, shimmer, harmonics-to-noise ratio, cepstral peak prominence, the relative energy levels of the first harmonic, the first formant and the third formant, the spectral slope in the low-frequency zone (0-1 kHz and 0-2 kHz), and the relative level of energy above 6 kHz. Distribution of spectral energy was analyzed from a long-term average spectrum of 40 seconds of text. Laryngeal aerodynamic measurements were obtained for one patient before and after onset of paralysis using the Aerophone II (Kay Elemetrics). Pitch and amplitude perturbation increased secondary to UVFP, while the harmonics-to-noise ratio and the cepstral peak prominence decreased. A relative increase in the mid-frequency and high-frequency ranges and a decrease in the low-frequency spectral slope were observed. Mean airflow rate and intraoral pressure increased, and glottal resistance and vocal efficiency decreased secondary to UVFP. The findings of this self-paired study confirm some but not all the results of previous studies. Measures involving the fundamental and the formants did not corroborate previous findings. Further investigation with vocal tract modeling is warranted.     

The Relationship Between Cepstral Peak Prominence and Selected Parameters of Dysphonia

Traditional measures of dysphonia vary in their reliability and in their correlations with perceptions of grade. Measurements of cepstral peak prominence (CPP) have been shown to correlate well with perceptions of breathiness. Because it is a measure of periodicity, CPP should also predict roughness. The ability of CPP and other acoustic measures to predict overall dysphonia and the subcategories of breathiness and roughness in pathological voice samples is explored. Preoperative and postoperative speech samples from 19 patients with unilateral recurrent laryngeal nerve paralysis who underwent operative intervention were analyzed by trained listeners and by measures of smoothed CPP (CPPS), noise-to-harmonic ratio (NHR), amplitude perturbation quotient (APQ), relative average perturbation (RAP), and smoothed pitch perturbation quotient (sPPQ). The data were analyzed with bivariate Pearson correlation statistics. Grade of dysphonia and breathiness ratings correlated better with measurements of CPPS than with the other measures. CPPS from samples of connected speech (CPPS-s) best predicted overall dysphonia. None of the measures were useful in predicting roughness.     

Objective Indices of Perceived Vocal Strain

BackgroundA limited number of experiments have investigated the perception of strain compared to the voice qualities of breathiness and roughness despite its widespread occurrence in patients who have hyperfunctional voice disorders, adductor spasmodic dysphonia, and vocal fold paralysis among others.ObjectiveThe purpose of this study is to determine the perceptual basis of strain through identification and exploration of acoustic and psychoacoustic measures.MethodsTwelve listeners evaluated the degree of strain for 28 dysphonic phonation samples on a five-point rating scale task. Computational estimates based on cepstrum, sharpness, and spectral moments (linear and transformed with auditory processing front-end) were correlated to the perceptual ratings.ResultsPerceived strain was strongly correlated with cepstral peak prominence, sharpness, and a subset of the spectral metrics. Spectral energy distribution measures from the output of an auditory processing front-end (ie, excitation pattern and specific loudness pattern) accounted for 77–79% of the model variance for strained voices in combination with the cepstral measure.ConclusionsModeling the perception of strain using an auditory front-end prior to acoustic analysis provides better characterization of the perceptual ratings of strain, similar to our prior work on breathiness and roughness. Results also provide evidence that the sharpness model of Fastl and Zwicker (2007) is one of the strong predictors of strain perception.     

Cepstral and Perceptual Investigations in Female Teachers With Functionally Healthy Voice

PurposeThe present study aimed at measuring the smoothed and non-smoothed cepstral peak prominence (CPPS and CPP) in teachers who considered themselves to have normal voice but some of them had laryngeal pathology. The changes of CPP, CPPS, sound pressure level (SPL) and perceptual ratings with different voice tasks were investigated and the influence of vocal pathology on these measures was studied.MethodEighty-four Finnish female primary school teachers volunteered as participants. Laryngoscopically, 52.4% of these had laryngeal changes (39.3% mild, 13.1% disordered). Sound recordings were made for phonations of comfortable sustained vowel, comfortable speech, and speech produced at increased loudness level as used during teaching. CPP, CPPS and SPL values were extracted using Praat software for all three voice samples. Sound samples were also perceptually evaluated by five voice experts for overall voice quality (10 point scale from poor to excellent) and vocal firmness (10 point scale from breathy to pressed, with normal in the middle).ResultsThe CPP, CPPS and SPL values were significantly higher for vowels than for comfortable speech and for loud speech compared to comfortable speech (P < 0.001). Significant correlations were found between SPL and cepstral measures. The loud speech was perceived to be firmer and have a better voice quality than comfortable speech. No significant relationships of the laryngeal pathology status with cepstral values, perceptual ratings, or voice SPLs were found (P > 0.05).ConclusionNeither the acoustic measures (CPP, CPPS, and SPL) nor the perceptual evaluations could clearly distinguish teachers with laryngeal changes from laryngeally healthy teachers. Considering no vocal complaints of the subjects, the data could be considered representative of teachers with functionally healthy voice.     

Classification of Dysphonic Voice: Acoustic and Auditory-Perceptual Measures

The purpose of this study was (1) to determine the relationship between acoustic measures and auditory-perceptual dimensions of overall voice severity and pleasantness and (2) to evaluate the ability of acoustic and auditory-perceptual measures to discriminate normal from dysphonic voices. Thirty adult dysphonic speakers and six, age-matched normal control speakers were asked to provide oral reading samples of the Rainbow Passage. Acoustic analysis of the speech samples was used to identify abnormal phonatory events associated with dysphonia. The acoustic program calculated long-term average spectral measures, glottal noise measures, and those measures based on linear prediction (LP) modeling. Twelve adult listeners judged overall voice severity and pleasantness from the connected speech samples using direct magnitude estimation (DME) procedures. The acoustic measures accounted for 48% of overall voice severity and 40% of voice pleasantness for dysphonic speakers. The classification performance of the acoustic measures and auditory-perceptual measures was quantified using logistic regression analysis. When acoustic measures or auditory-perceptual measures were considered in isolation, classification was generally accurate and similar across measures. Classification accuracy improved to 100% when acoustic and auditory-perceptual measures were combined. These data provide further support for use of both auditory-perceptual evaluation and acoustic analyses for classifying and evaluating dysphonia.     

Spectral- and Cepstral-Based Measures During Continuous Speech: Capacity to Distinguish Dysphonia and Consistency Within a Speaker

Spectral- and cepstral-based acoustic measures are preferable to time-based measures for accurately representing dysphonic voices during continuous speech. Although these measures show promising relationships to perceptual voice quality ratings, less is known regarding their ability to differentiate normal from dysphonic voice during continuous speech and the consistency of these measures across multiple utterances by the same speaker. The purpose of this study was to determine whether spectral moments of the long-term average spectrum (LTAS) (spectral mean, standard deviation, skewness, and kurtosis) and cepstral peak prominence measures were significantly different for speakers with and without voice disorders when assessed during continuous speech. The consistency of these measures within a speaker across utterances was also addressed. Continuous speech samples from 27 subjects without voice disorders and 27 subjects with mixed voice disorders were acoustically analyzed. In addition, voice samples were perceptually rated for overall severity. Acoustic analyses were performed on three continuous speech stimuli from a reading passage: two full sentences and one constituent phrase. Significant between-group differences were found for both cepstral measures and three LTAS measures (P < 0.001): spectral mean, skewness, and kurtosis. These five measures also showed moderate to strong correlations to overall voice severity. Furthermore, high degrees of within-speaker consistency (correlation coefficients ≥0.89) across utterances with varying length and phonemic content were evidenced for both subject groups.     

LIBS与反向传播算法结合的橄榄石成分分析

LIBS是一项用于分析物质成分的有力手段，但是定量分析时存在结果不准确、重复性低等缺点。为了准确预测自然界中橄榄石的成分信息，通过按照自然界中的橄榄石的成分信息制作15组橄榄石样品，将其中的11组作为标准样品，另外4组作为测试样品进行LIBS定量分析。每个样本采50条LIBS光谱建立橄榄石的LIBS数据库。然后采用多元线性回归算法和反向传播算法对样本的50组数据进行分析，有效的降低了由于随机误差造成的测试结果的不准确。最终结果表明，使用激光诱导击穿光谱和反向传播算法对橄榄石中镁橄榄石与铁橄榄石含量进行检测，预测结果的决定系数为0.901，接近常规的多元线性回归算法得到的0.911，这说明反向传播算法对橄榄石含量的预测精度接近多元线性回归算法。同时使用反向传播算法得到的结果的均方根误差为28.64，优于后者的29.23，说明使用反向传播算法得到的结果分布更加集中。此外，通过分析关联矩阵中各数值的大小与各元素谱线的位置的对应关系，表明使用反向传播算法反演出来的关联矩阵F与之所代表的物理含义的相关性更高。说明反向传播运算不仅与传统的多元线性回归算法性能相当，而且在预测数据的一致性上表现得更好。此外使用反向传播算法可以直接对激光诱导击穿光谱得到的橄榄石全谱数据进行数据反演，而不需要经过光谱寻峰这一步骤，简化了数据分析流程，弥补了多元线性回归算法难以分析全谱数据的不足。     

The Effect of Noise on Computer-Aided Measures of Voice: A Comparison of CSpeechSP and the Multi-Dimensional Voice Program Software Using the CSL 4300B Module and Multi-Speech for Windows

The effect of noise on computer-derived samples of voice was compared across three different hardware/software configurations. The hardware/software systems included a stand-alone A/D converter (CSL Module 4300B) coupled to a custom Pentium PC used in conjunction with the Multi-Dimensional Voice Program (MDVP) software, and a Creative Labs A/D converter coupled to the same custom PC under software control of MDVP/Multispeech and CSpeechSP. Voice samples were taken from 10 female subjects, then mixed with computer fan noise creating three different signal-to-noise (S/N) levels. Mixed signals were analyzed on the three hardware/software systems. Results revealed that fundamental frequency was most resistant to the degradation effect of noise across systems; jitter and shimmer values, however, were more variable across all configurations. Jitter and shimmer values were significantly higher under certain S/N levels for the MDVP 4300B based system as compared to MDVP for Multi-Speech and CSpeechSP. The findings punctuate the need for sensitivity to recording environments, careful selection of hardware/software equipment arrays, and the establishment of minimal recording conditions (>25 dBA S/N) for voice sampling and analysis using computer-assisted methods.     

Effect of Dysphonia and Cognitive-Perceptual Listener Strategies on Speech Intelligibility

There is a high prevalence of dysphonia among professional voice users and the impact of the disordered voice on the speaker is well documented. However, there is minimal research on the impact of the disordered voice on the listener. Considering that professional voice users include teachers and air-traffic controllers, among others, it is imperative to determine the impact of a disordered voice on the listener. To address this, the objectives of the current study included: (1) determine whether there are differences in speech intelligibility between individuals with healthy voices and those with dysphonia; (2) understand whether cognitive-perceptual strategies increase speech intelligibility for dysphonic speakers; and (3) determine the relationship between subjective voice quality ratings and speech intelligibility. Sentence stimuli were recorded from 12 speakers with dysphonia and four age- and gender-matched typical, healthy speakers and presented to 129 healthy listeners divided into one of three strategy groups (ie, control, acknowledgement, and listener strategies). Four expert raters also completed a perceptual voice assessment using the Consensus Assessment Perceptual Evaluation of Voice for each speaker. Results indicated that dysphonic voices were significantly less intelligible than healthy voices (P ≤ 0.001) and the use of cognitive-perceptual strategies provided to the listener did not significantly improve speech intelligibility scores (P = 0.602). Using the subjective voice quality ratings, regression analysis found that breathiness was able to predict 41% of the variance associated with number of errors (P = 0.008). Overall results of the study suggest that speakers with dysphonia demonstrate reduced speech intelligibility and that providing the listener with specific strategies may not result in improved intelligibility.     

Vocal stability in functional dysphonic versus healthy voices at different times of voice loading

Functional (nonorganic) dysphonia is often characterized by vocal instability. The purpose of the prospective study was to examine whether there is a difference in vocal instability of functional dysphonic voices compared with healthy ones, this means whether electroglottographic perturbation values differ (1) between healthy and dysphonic voices and (2) between two subgroups of the dysphponic voices (hpertonic and hypotonic dysphonic voices). Twenty-three patients with hypertonic functional dysphonia, 9 with hypotonic functional dysphonia and 31 healthy nonsmokers, were each examined electroglottographically before (Ex 1), immediately after (Ex 2), and 1 hour after (Ex 3) voice loading. Perturbations of frequency, amplitude, quasi-open-quotient, and contact-index were calculated from the EGG signal. At all three times of examination, hypertonic dysphonic voices showed higher perturbations than healthy voices, and they had higher perturbations than hypotonic dysphonic voices before and 1 hour after voice loading. Hypotonic dysphonic voices showed higher perturbations than healthy voices only 1 hour after voice loading. Voice loading induced different reactions in dysphonic voices: Some voices showed increased perturbations, and others exhibited normal or even decreased perturbation immediately after voice loading. Examination of electroglottographic-derived perturbations immediately after voice loading seems not to be useful. Differentiation of hypertonic and hypotonic dysphonic voices was possible with an estimated sensitivity of 88.9% and a specificity of 87.0% by using the sum of the amplitude-perturbation and the quasi-open-quotient-perturbation measured before voice loading.     

Voice Quality in Laryngeal Cancer Patients: A Randomized Controlled Study of the Effect of Voice Rehabilitation

ObjectivesThe study aimed to investigate the short-term and long-term effects of voice rehabilitation in patients treated with radiotherapy for laryngeal cancer as measured by both the acoustic measure smoothed cepstral peak prominence (CPPS) and perceptual measures. A secondary aim was to investigate the relationship between acoustic and perceptual measures.MethodsIn total, 37 patients received voice rehabilitation post-radiotherapy and 37 patients constituted the irradiated control group. Outcome measures were mean CPPS for connected speech and ratings with the auditory-perceptual Grade, Roughness, Breathiness, Asthenia and Strain (GRBAS) scale. Outcome measures were analyzed 1 (baseline), 6, 12, and 24 months post-radiotherapy, where voice rehabilitation was conducted between the first two time-points. Additional recordings were acquired from vocally healthy participants for comparison.ResultsCPPS values of the voice rehabilitation group and vocally healthy group were not significantly different at 24 months post-radiotherapy. Ten out of 19 patients who received voice rehabilitation yielded a CPPS value above the threshold for normal voice 24 months post-radiotherapy, compared to 11 out of 26 in the irradiated control group. No statistically significant correlations were found between CPPS and perceptual parameters of GRBAS.ConclusionVoice rehabilitation for irradiated laryngeal cancer patients may have positive effects on voice quality up to 24 months post-radiotherapy. The relationship between CPPS and GRBAS as well as the applicability of CPPS for evaluation over several points of measurement needs to be studied further.     

Use of acupuncture for the treatment of adductor spasmodic dysphonia: a preliminary investigation

Ten subjects with adductor spasmodic dysphonia participated in a study examining the effects of an acupuncture treatment protocol on their voice disorder. Treatment consisted of eight sessions, and it was designed and performed by two physicians certified in acupuncture. Voice characteristics were evaluated pretreatment and posttreatment using the CSL Motor Speech Profile (MSP), Unified Spasmodic Dysphonia Rating Scale, and Voice Handicap Index (VHI). Subjects also answered a posttreatment questionnaire regarding their experience. Significant pretreatment and posttreatment differences occurred for some MSP measures. Significant differences were found on all three subtests of the VHI, and the average total scores pretreatment and posttreatment differed by 17 points (considered significant according to VHI standardization). Seven of 10 subjects reported improvements in voice production, although expert raters did not detect perceptual changes in voice quality. Possible reasons for the discrepancies between objective measures and self ratings, and implications for further research, are discussed.     

Acoustic Measures of Symptoms in Abductor Spasmodic Dysphonia

Speech of patients with abductor spasmodic dysphonia (ABSD) was analyzed using acoustic analyses to determine: (1) which acoustic measures differed from controls and were independent factors representing patients' voice control difficulties, and (2) whether acoustic measures related to blinded perceptual counts of the symptom frequency in the same patients. Patients' voice onset time for voiceless consonants in speech were significantly longer than the controls (p = 0.015). A principle components analysis identified three factors that accounted for 95% of the variance: the first factor included sentence and word duration, frequency shifts, and aperiodic instances; the second was phonatory breaks; and the third was voice onset time. Significant relationships with perceptual counts of symptoms were found for the measures of acoustic disruptions in sentences and sentence duration. Finally, a multiple regression demonstrated that the acoustic measures related well with the perceptual counts (r² = 0.84) with word duration most highly related and none of the other measures contributing once the effect of word duration was partialed out. The results indicate that some of the voice motor control deficits, namely aperiodicity, phonatory breaks, and frequency shifts, which occur in patients with ABSD, are similar to those previously found in adductor spasmodic dysphonia. Results also indicate that acoustic measures of intermittent disruptions in speech, voice onset time, and speech duration are closely related to the perception of symptom frequency in the disorder.     

The Relationship Between Perceptual Evaluation and Objective Multiparametric Evaluation of Dysphonia Severity

SUMMARY: The purpose of this study was to investigate the usefulness of the Dysphonia Severity Index (DSI) as an objective multiparametric measurement in assessing dysphonia. The DSI was compared with the score on Grade of the GRBAS scale. Investigated was also whether the DSI is related to severity of dysphonia, which was represented by different diagnosis groups. Furthermore, it was investigated whether the DSI can differentiate between a group of patients and a control group. A total of 294 patients with different voice pathologies were included. A control group consisted of 118 volunteers without any voice complaints. The voices of all participants were perceptually evaluated on Grade, and the DSI was measured. The groups of patients with voice complaints have a lower DSI and higher scores on Grade than the control group. The DSI was significantly lower when the score on Grade was higher. The DSI discriminates between patients with nonorganic voice disorders, vocal fold mass lesions, and vocal fold paresis/paralysis. To determine whether the DSI discriminates between patients and controls, the sensitivity and specificity for different DSI cutoff points were calculated. With a DSI cutoff of 3.0, maximum sensitivity (0.72) and specificity (0.75) were found. We conclude that the DSI is a useful instrument to objectively measure the severity of dysphonia.     

Clinical Characteristics and Voice Analysis of Patients With Mutational Dysphonia: Clinical Significance of Diplophonia and Closed Quotients

The aim of this study was to investigate the acoustic and electroglottographic characteristics of patients with mutational dysphonia before and after voice therapy. The clinical records of 15 patients with mutational dysphonia were reviewed, and their voice recordings were analyzed with the help of the Lx Speech Studio program (Laryngograph Ltd, London, UK). After voice therapy combined with the manual compression method, the subjects' voices lowered in pitch and improved in quality. In addition, we classified the mutational dysphonia into four categories according to the presence of diplophonia and closed quotients. The most common type among the categories was characterized by a bimodal distribution of fundamental frequency (diplophonia), accompanied by a low closed quotient (falsetto voice) at high frequencies. However, the results also showed that mutational dysphonia cannot be generalized as always having a falsetto voice, as shown in other types. The effect of therapy was different for each type, and those cases with both diplophonia and a non-trained falsetto voice could be treated more readily. Consequently, the diplophonia and closed quotient, which were easily analyzed using Lx Speech Studio program, are important factors in the classification of mutational dysphonia. Identification of these characteristics may affect treatment choices, facilitate monitoring of the efficacy of therapy, and aid in estimating prognosis.     

Acoustical analysis and perceptual evaluation of tracheoesophageal prosthetic voice

Voice analysis was performed on 21 “standard” laryngectomized, male patients with a Provox® voice prosthesis, along with an age- and sex-matched control group of 20 normal speakers, using acoustical analyses (MDVP and CSL, Kay Elemetrics Corp.), maximum phonation time measurements, and perceptual evaluations. Comparison between MDVP and CSL revealed that the latter was not useful for the analysis of laryngectomized prosthetic voices. In contrast, MDVP seems suitable for this purpose, and contains a large number of parameters that significantly differentiate between patient and control speakers, as did the perceptual ratings and the maximum phonation time. Fundamental frequency appeared to be comparable for patients and control speakers. A significant influence of stoma occlusion and age was found for some voice parameters. Factor analyses showed correlations between the different MDVP parameters and correlations between the MDVP parameters and the perceptual ratings.     

Noise-to-Harmonics Ratio as an Acoustic Measure of Voice Disorders in Boys

This prospective study assessed the efficacy of computerized noise-to-harmonics ratio (NHR) to quantify perceptual and endoscopic findings of dysphonia and/or structural lesion of the vocal fold. Fifty Brazilian boys without vocal complaints were submitted to computerized, perceptual, and endoscopic examination. Thirty boys were dysphonic--3 were classified into the grade category, 5 into breathiness, 9 into roughness, and 15 into grade/breathiness. Vocal fold lesions were observed in 25 boys (17 nodules and 8 cysts). The Mann-Whitney U test revealed that NHR was significantly higher in boys with a structural lesion (p = 0.007) and in boys with dysphonia (p < 0.0001). However, according to a logistic regression model, only the occurrence of dysphonia was explained by NHR; the risk for having dysphonia increased approximately twice (odds ratio = 1.92, 95% confidence interval = 1.3-2.9) with each increase of 0.01 in NHR. Our results suggest that noise is a useful quantitative index to confirm a perceptual diagnosis of dysphonia and to evaluate quantitative changes in a dysphonic voice over time. However, we believe that computerized analysis should be used as a complement, rather than a substitute, for perceptual evaluation. Further studies with a larger sample are required to investigate the relationship between noise and lesions of the vocal folds.     

基于表面增强拉曼的饮料中山梨酸钾快速定量检测方法

基于实验室自行搭建的拉曼光谱点扫描系统,利用表面增强拉曼技术对橙味饮料中山梨酸钾的含量进行了定量快速检测研究。通过与山梨酸钾标准品拉曼光谱及其水溶液表面增强拉曼光谱等比较分析,确定了山梨酸钾1 648.4,1 389.3和1 161.8 cm-1处的表面增强特征拉曼位移。通过山梨酸钾橙味饮料平行样品的拉曼位移峰强重现性实验并计算其峰强的相对标准偏差证实了该表面增强拉曼方法具有较好的重复性。采集了山梨酸钾浓度范围为1.706～0.180 7 g·kg-1的33个橙味饮料样品的表面增强拉曼光谱,所有原始光谱经S-G 5点平滑及Baseline基线去除荧光背景预处理后分别用一元线性回归分析、多元线性回归分析和偏最小二乘回归分析方法,建立了山梨酸钾的定量预测模型。经比较,选取三个山梨酸钾拉曼特征位移1 161.8,1 389.3和1 648.4 cm-1所建立的多元线性回归模型校正集的相关系数(R2_C)和均方根误差(RMSEC)分别为0.983 7和0.051 7 g·kg-1,验证集的相关系数(R2_P)和均方根误差(RMSEP)分别为和0.969 9和0.052 8 g·kg-1,比一元线性回归模型和偏最小二乘回归模型误差小、精度高。基于表面增强拉曼完全可以实现橙味饮料中山梨酸钾的定量快速预测,为各类食品中山梨酸钾含量的快速监测奠定了技术基础。     

Patient Versus Partner Perception of Voice Handicap

The primary purpose of this study was to compare patient's and communication partner's perceptions of handicap secondary to dysphonia. A secondary purpose was to compare patient health-related quality of life (HRQOL) to that of speakers with normal voice. Participants were 20 adults (mean age=69.15 years) with dysphonia and their communication partners. Patients completed the Voice Handicap Index (VHI), a questionnaire of self-perceived voice handicap, and the Short-Form 36 (SF-36), a general health questionnaire. Partners completed the Voice Handicap Index-Partner (VHI-P), a questionnaire derived from the VHI for this pilot study, to gauge partner perception of voice handicap. Patients in this study viewed themselves as only moderately handicapped by their dysphonia and their partners were in close agreement. Patients and their partners were also in close agreement on each of three VHI subscales (physical, functional, and emotional), and in all cases the physical domain was perceived by both patients and their partners to be most handicapped. Patients had lower SF-36 mean scores than those of persons with normal voice from the general U.S. population on scales assessing physical functioning, physical role, general health, vitality, social functioning, emotional role, and mental health. The results of this study are consistent with previous studies examining patient-partner agreement, which consider proxy ratings to be a useful alternative or collaborative source of patient's self-perception. Further research regarding the reliability of patient and partner agreement is necessary to most effectively assess and manage patients with dysphonia.     

Effects of spatial smoothing on fMRI group inferences

The analysis of functional magnetic resonance imaging (fMRI) data involves multiple stages of data pre-processing before the activation can be statistically detected. Spatial smoothing is a very common pre-processing step in the analysis of functional brain imaging data. This study presents a broad perspective on the influence of spatial smoothing on fMRI group activation results. The data obtained from 20 volunteers during a visual oddball task were used for this study. Spatial smoothing using an isotropic gaussian filter kernel with full width at half maximum (FWHM) sizes 2 to 30 mm with a step of 2 mm was applied in two levels — smoothing of fMRI data and/or smoothing of single-subject contrast files prior to general linear model random-effects group analysis generating statistical parametric maps. Five regions of interest were defined, and several parameters (coordinates of nearest local maxima, t value, corrected threshold, effect size, residual values, etc.) were evaluated to examine the effects of spatial smoothing. The optimal filter size for group analysis is discussed according to various criteria. For our experiment, the optimal FWHM is about 8 mm. We can conclude that for robust experiments and an adequate number of subjects in the study, the optimal FWHM for single-subject inference is similar to that for group inference (about 8 mm, according to spatial resolution). For less robust experiments and fewer subjects in the study, a higher FWHM would be optimal for group inference than for single-subject inferences.