Fundamental Frequency and Diadochokinetic Jitter in Multiple Sclerosis Kimberlee Wassink and J. Anthony Seikel Ph.D. Idaho State University Department of Communication Sciences & Disorders, and Education of the Deaf Poster formatted by Jackie Stokes Method Results Background Dysarthria is characterized by disturbed movements of the speech musculature, which may be slow, weak, imprecise, or uncoordinated (Hartelius, Svensson, & Bubach, 1993). The difficulties experienced with dysarthria cause a degeneration in speech quality, resulting from the alterations of muscle function in each of the systems of speech. Degenerative diseases can cause either global deterioration or focus upon one or more systems of the speech mechanisms. The site of lesion is a strong predictor of type of dysarthria. Hartelius, et al. (1995) reported that several of the perceptual speech symptoms of MS are attributable to respiratory insufficiency or dysfunction. Indeed, a majority of the subjects in the study by Murdoch, Cherery, Stokes, and Hardcastle (1991) exhibited discoordinated irregular chest wall movements and jerkiness in performing sustained vowels and syllable repetition tasks, as well as during reading and conversation. Darley, et al. (1975) describe MS patients as having scanning speech, a term used to describe impaired emphasis. Hartelius et al. (1995) did not find difference between MS patients and controls on mean fundamental frequency. The temporal domain extends into the suprasegmental arena, which involves duration of elements that extend beyond phoneme (or even word) boundaries. Diadochokinesis (DDK), or the ability to rapidly repeat relatively simple patterns of vowels and consonants, is a task that examines, among other things, temporal aspects of speech that span single phoneme boundaries (Baken, 1987). Vocal jitter is defined by, Blomgren, Chen, Ng, and Gilbert (1998) as a percentage of frequency that can be calculated by taking the absolute difference between consecutive fundamental frequencies (in Hz), and dividing it by the mean fundamental frequency (Blomgren, et al., 1998). This study calculated cycle-by-cycle variability in DDK (or DDK jitter) utilizing a modified version of this formula. In the case of this study, diadochokinetic jitter, which is defined as the syllable-by-syllable variability in DDK production, was derived by summing the absolute differences between adjacent syllable duration and also deriving the mean syllable duration. This sum was then divided by the mean duration and multiplied by one hundred to be expressed as a percentage. The two research questions addressed in this study were: 1) Is there a significant difference in the mean fundamental frequency between MS participants and control participants? And 2) Is there a significant difference in the mean diadochokinetic jitter between MS participants and control participants? Baken, R. (1987). Clinical measurement of speech and voice. Austin: Pro-Ed Inc. Blomgren, M., Chen, Y., Ng, M., & Gilbert, H. (1998). Acoustic, aerodynamic, physiologic, and perceptual properties of modal and vocal fry registers. Journal of the Acoustical Society of America, 103(5), Brown, J., Darley, F., & Aronson, A. (1970). Ataxic dysarthria. International Journal of Neurology, 7(2), Darley, F., Brown, J., & Aronson, A. (1969). Differential diagnostic patterns of dysarthria. Journal of Speech and Hearing Research, 12(2), Darley, F., Brown, J., & Aronson, A. (1969). Clusters of deviant speech dimensions in the dysarthrias. Journal of Speech and Hearing Research, 12(3), Darley, F., Brown, J., & Aronson, A. (1975). Motor speech disorders. Philadelphia: W.B. Saunders Company. 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Journal of Speech and Hearing Research, 34, References Discussion The analysis of the mean fundamental frequency comparing MS participants with control participants revealed results that strikingly contradict the study completed by Hartelius, et al. (1995), in which she found that no significant differences exist in fundamental frequency between five MS participants and two control participants. These results also contradict results found in a study by Feijo, et al. (2004) regarding fundamental frequency in MS. The study reported that fundamental frequency was higher among MS individuals versus controls. However, this study was greatly skewed by gender within the groups. The present study used analysis that compared the fundamental frequencies separately between the genders and used the same number of females and males in both groups. This study found a significant difference during the production of /a/, however not for the production of /i/. Diadochokinetic Jitter The DDK task may be viewed as revealing the ataxic component of the mixed dysarthria. This is apparent in that there are variations in the duration of each component during the production of DDK tasks, demonstrating difficulty with coordination of muscle movements. It is hypothesized that these difficulties are a direct result of ataxic dysarthria and cerebellar disorder. The cerebellum controls coordination, timing, and initiation and termination of individual muscle movements (Hartelius, et al., 2000). These results are in agreement with Kent, et al. (1997) which indicated that the participants with ataxic dysarthria demonstrated increased variability of segments during syllable repetition. These results also are consistent with Hartelius, et al. (2000) who determined that the MS group demonstrated significantly longer syllables and increased inter-utterance variation in the duration of multi-syllabic productions. In this study, further evaluation of the results of ANOVA testing revealed that it appears that the DDK syllable /t4/ is the most sensitive production for detecting DDK jitter. It may be that production of /t4/ involves more intricate coordination among the systems of speech than the other syllables. Indeed the /t4/ syllable involves tongue tip, jaw, larynx and lip coordination. This information is supportive of the findings in Hartelius and Lillvik (2003), in which they found that tongue function is more significantly affected than lip function both when compared within the MS group and when compared with a control group. In addition the Hartelius and Lillvik study found that tongue function alone was affected (though not as significantly) in MS participants who were identified as not having dysarthria, implying that the MS in itself can affect tongue movement regardless of dysarthria. Because the analysis of the syllable /t4/ was able to identify a significant difference between the MS and control groups as a whole, it would be assumed that one would not need to measure the durations of the consonant, the vowel, and the silent period separately. Hartelius and Lillvik (2003) identified that testing tasks that required quick rates of movement of the tongue were more significantly impaired than tasks which required either force of movement, or range of motion. With this finding in mind, this single syllable (/t4/) measurement in diadochokinesis may be enough to determine if there is a large percentage of jitter and may be enough to give a positive indicator of ataxic dysarthria. Hartelius and Lillvik (2003) agree that before identifying a treatment plan it is critical that you determine which articulators are more severely affected than others, or in this case, even determining which type of dysarthria would lead to a narrowed area of affected articulators. From this study it seems that the combination of determining fundamental frequency and using DDK jitter may prove to be a useful clinical tool for determining the effects of spastic and ataxic dysarthria on speech, in MS or in any other disease. These measurements and analyses provide information that it may be possible to identify the dominant form of dysarthria, therefore providing the clinician with more evidence for a diagnosis and a starting point for a plan of treatment for these individuals. Participants Twenty individuals with definite diagnosis of multiple sclerosis (MS) as confirmed by MRI and the Expanded Disability Status Scale (EDSS)(Kurtzke, 1983) served as subjects for this study. Twenty control participants were matched for age, gender, and educational level. All twenty pairs were used in the determination of difference in fundamental frequency for /i/ and /a/ vowels, while 12 of these were used for determination of DDK jitter. Data collection was completed in Greece, the participants were all from the Athens region, and all participants spoke Greek. Materials Audio and electrolaryngography recordings were made using a laryngograph, a Sony digital audio tape (DAT) recorder, and an oscilloscope. Subjects were recorded in a sound attenuated audiology booth. Acoustical analysis was performed using the Kay Computerized Speech Lab and the Sony Sound Forge Audio 7.0 software. Participants were asked to perform four tasks: 1. Sustained vowels /a/ and /i/. 2. Reading of a paragraph in Greek. 3. Monologue 4. Rapid repetition of consonant vowel pairs (diadochokinesis). Procedure The fundamental frequency was calculated using a two-second time period beginning one second following the onset of the sustained vowels /a/ and /i/. DDK jitter was calculated for the durations of the initial burst and consonant, the vowel and the silent periods individually. A two (group) by two (gender) ANOVA was calculated to identify differences in fundamental frequency between MS and Control. Results revealed the predicted significance based on gender [F(1,18) = ], as well as a main effect for group [F(1,18) = 9.151]. The fundamental frequency for MS was significantly lower (MN = 154.8) than that of the control participants (MN = 183.9) for /a/, but not for /i/. Figure 1: Measurement of Consonant Duration. Note that the area marked represents the region defined by the study criteria as being the consonant; a) marks the onset and b) the termination point. Figure 2: Measurement criteria for vowel duration. Note that the marked area indicates that which was considered vowel in the present study; a) marks the onset and b) the termination point. Figure 3: Measurement of silent post-vocalic period. Note that the marked region indicates the silent interval; a) marks the onset and b) the termination point. The mean percent of total diadochokinetic jitter, consonant diadochokinetic jitter, vowel diadochokinetic jitter, and silent period diadochokinetic jitter was calculated for each consonant vowel pair, and were subsequently subjected to a 2 (gender) by 2 (group) ANOVA. Results revealed that, for the vowel in the /p4/ syllable, the MS group (MN =21.20) showed significantly greater DDK jitter than the controls (MN =14.87, p =.026). Similarly, the DDK jitter for the entire /t4/ syllable was significant (MN = for MS; MN = for control; p =.031). Mean Fundamental Frequency for the vowel /a/ Mean Fundamental Frequency for the vowel /i/ Results are discussed in terms of the effects of the mixed spastic-ataxic dysarthria on the two tasks of the study, as well as comparison with the Hartelius et al. (1995) study. Mean Fundamental Frequency This study revealed a way to differentiate the effects of spastic and ataxic dysarthria separately by using different tasks. In this sample it appears that spastic dysarthria was the dominant dysarthria component during production of the sustained vowel /a/, as verified by the significant statistical difference in the mean fundamental frequency between the MS and control groups. Indeed, individuals with spastic dysarthria tend to have lower perceived pitch as well as harsh voice. For example, Darley, et al. (1975) described the phonation in a person with spastic dysarthria as one who sounds as if he or she is forcing a breath stream through a narrowed airway. Darley, et al. also describe the tone of voice as having a harsh quality, which may likely to lead to the perception of a lower pitch. In addition, Darley et al. (1969) reported that, in a study completed at the Mayo Clinic, twenty-six of thirty patients presented with excessively low pitch, which was a joint sign, along with the harsh quality, of dysphonic voice production. With this research in mind, it is not surprising that this study found the fundamental frequency in participants with MS to be lower than control participants, as spastic dysarthria is one of the main characteristics of MS. Factors which may have had an affect of voice production and quality: 1. Emotion 2. Stress 3. Lifestyle In this study the Mini-Mental Status Exam (MMSE) (Folstein, M., Folstein, S., & McHugh, P. 1975) and the Hamilton Depression Scale (HAM-D) (Hedlung, & Vieweg, 1979) were used to determine if either emotional state or depression were playing a part in altering the voice characteristics of the individuals participating in the study. Emotion and depression were determined not be contributing factors in the voice production of these individuals. It was determined that in terms of lifestyle that it should be kept in mind that several of the participants were smokers.