knowledge about dysphonia manifestations and the degree of commitment that this change 
 causes in laryngeal and vocal behavior are important for defining rehabilitation 
 direction . in order to do that , procedures are necessary for clinical assessment . 
 perceptual and acoustic assessments , among other procedures , are commonly 
 performed .
oral and vocal fold diadochokinesis ( ddk ) is one of the tests that can be applied to 
 perform acoustic analysis .
the ddk , or syllable alternating motion rate , is the ability to perform rapidly 
 opposite contractions of relatively simple patterns .
vocal fold ddk analysis allows evaluation of 
 neuromuscular integrity of the vocal folds and oral ddk analyzes the ability to perform quick repetitions of 
 speech segments .
some studies try to 
 understand the vocal manifestation of dysphonic patients through the perceptual and 
 acoustic analysis of voice .
( 2008 ) evaluated voice acoustic parameter changes in patients with 
 parkinson 's disease ( pd ) who were searching for their relationship with motor control . 

the voices perceptual and acoustic ratings evaluations of 20 pd patients , 12 men and 8 
 women , were compared with the voices of 20 control subjects of corresponding ages and 
 genders .
patients with pd had smaller values for maximum phonation time and ddk compared to the 
 control group , while jitter , shimmer and average fundamental frequency ( f0 ) were similar 
 between the two groups .
although men have poorer performance in ddk than women , these 
 values were not statistically significant .
thus , only a few significant correlations 
 between vocal parameters and motor control were found .
the vocal fold ddk measurement indicates laryngeal gestures of opening and closing of 
 the vocal folds , being that changes in extension and speed movement of vocal folds will 
 reproduce changes in the production rate in patterns of duration and transglottic 
 airflow rate .
therefore , the presence 
 of organic and functional changes in dysphonia cases may relate to ddk results .
the ddk evaluation associated with other clinical assessment procedures is an important 
 resource in understanding the manifestations of individual communication disorders .
the 
 assessment of oral and vocal fold diadochokinesis ( ddk ) in individuals with voice 
 disorders may contribute to the understanding of factors that affect balanced vocal 
 production .
scientific studies that make use of this assessment tool support advances in 
 knowledge in this area and reflect the development of more appropriate therapeutic 
 planning .
consequently , the objective of this study was to compare the results of oral and vocal 
 fold ddk of dysphonic women to the results of oral and vocal fold ddk in women without 
 vocal disorders .
this study has been approved by the research ethical committee of the school of 
 dentistry of the university of so paulo , bauru campus .
the recordings were obtained in an acoustically treated studio , and the patients 
 remained seated with a headset microphone ( akg , model - c444pp ) positioned laterally 
 between 60 degrees and 5 cm from the labial commissure .
the emissions were recorded on a 
 intel pentium 4 computer ( cpu 2.040 ghz and 256 mb ram ) with 
 a 17 " lg flatron e7015 monitor and a creative audigy ii sound card .
the system also used 
 sound forge 7.0 professional audio software ( madison , wi , usa ) , with a sampling rate of 
 44.100 hz and a 16 bit mono channel .
the experimental group was composed of 28 women ranging in age from 19 to 54 years 
 old , diagnosed with dysphonia and referred for a voice assessment by a speech 
 pathologist and otorhinolaryngologist .
the control group included 30 nondysphonic 
 women age - matched with the experimental group who were evaluated in previous research 
 with normal adults .
the presence of central neurological diseases and the presence of communication 
 disorders were considered exclusion factors for both groups , with the exception of 
 dysphonia for the experimental group . during the oral and vocal fold ddk test isolated emissions
were requested ; namely , 
 the syllables " pa , " " ta " and " ka , " the sequence " pataka " and then the vowels " a " and 
 " i. " before the beginning of the test , the patient was requested to repeat the sound 
 as rapidly as possible .
the patients practiced the sounds before each recording by 
 repeating as fast as possible , after deep breathing , in a clear and precise way the 
 emissions with a comfortable frequency and intensity in order to understand how to 
 perform the test . soon thereafter
, the subjects were guided to perform the tasks , by 
 receiving a signal with the thumb to begin and to stop the repetition .
the " pa , " " ta , " " ka , " " pataka , " " a " and " i " emissions were edited by sound forge 7.0 
 professional audio editing professional .
software ( madison , wi , usa ) . the beginning 
 and end of each sample were excluded , except for four seconds from the third to the 
 sixth second . monosyllabic emissions " pa , " " ta " and " ka " and the vowels " a " and " i " were filed at 
 sampling rate of 11.025 hz , 16 bit mono channel and analyzed by advanced motor speech 
 profile program ( msp ) model 5141 version 2.5.2 ( kay 's elemetrics corp . , lincoln park , 
 nj , usa ) , whose parameters are described in figure 
 1 .
the msp program displays a graphical record of emissions showing the 
 horizontal axis ( time in seconds ) and the vertical axis ( energy in db ) . to do the ddk 
 count ,
the program drew a line in the central point at the energy scale of the 
 vertical axis in db .
the line of analysis was manually positioned in the 
 corresponding value to the intensity average of the ddk sample , provided by the msp 
 program , and moved up or down , so the program could count all emissions when 
 necessary ( figure 2 ) .
parameters for diadochokinesis ( ddk ) analyzed by advanced motor speech profile 
 ( msp ) program advanced motor speech profile ( msp ) program graphic , where time ( seconds ) on 
 the horizontal axis and energy ( db ) on the vertical axis can be observed the ddk of the " pataka " sequence was analyzed quantitatively through the sound forge 
 7.0 program .
the count of trisyllables per second was performed manually with the 
 auditory and visual waveform support displayed by the program .
average values of oral and vocal fold ddk in dysphonic and nondysphonic women were 
 correlated using the " t student " test and were considered significant when 
 p<0.05 .
the experimental group was composed of 28 women ranging in age from 19 to 54 years 
 old , diagnosed with dysphonia and referred for a voice assessment by a speech 
 pathologist and otorhinolaryngologist .
the control group included 30 nondysphonic 
 women age - matched with the experimental group who were evaluated in previous research 
 with normal adults .
the presence of central neurological diseases and the presence of communication 
 disorders were considered exclusion factors for both groups , with the exception of 
 dysphonia for the experimental group .
during the oral and vocal fold ddk test isolated emissions were requested ; namely , 
 the syllables " pa , " " ta " and " ka , " the sequence " pataka " and then the vowels " a " and 
 " i. " before the beginning of the test , the patient was requested to repeat the sound 
 as rapidly as possible .
the patients practiced the sounds before each recording by 
 repeating as fast as possible , after deep breathing , in a clear and precise way the 
 emissions with a comfortable frequency and intensity in order to understand how to 
 perform the test . soon thereafter
, the subjects were guided to perform the tasks , by 
 receiving a signal with the thumb to begin and to stop the repetition .
the " pa , " " ta , " " ka , " " pataka , " " a " and " i " emissions were edited by sound forge 7.0 
 professional audio editing professional .
the beginning 
 and end of each sample were excluded , except for four seconds from the third to the 
 sixth second .
monosyllabic emissions " pa , " " ta " and " ka " and the vowels " a " and " i " were filed at 
 sampling rate of 11.025 hz , 16 bit mono channel and analyzed by advanced motor speech 
 profile program ( msp ) model 5141 version 2.5.2 ( kay 's elemetrics corp .
, lincoln park , 
 nj , usa ) , whose parameters are described in figure 
 1 .
the msp program displays a graphical record of emissions showing the 
 horizontal axis ( time in seconds ) and the vertical axis ( energy in db ) . to do the ddk 
 count
, the program drew a line in the central point at the energy scale of the 
 vertical axis in db .
the line of analysis was manually positioned in the 
 corresponding value to the intensity average of the ddk sample , provided by the msp 
 program , and moved up or down , so the program could count all emissions when 
 necessary ( figure 2 ) .
parameters for diadochokinesis ( ddk ) analyzed by advanced motor speech profile 
 ( msp ) program advanced motor speech profile ( msp ) program graphic , where time ( seconds ) on 
 the horizontal axis and energy ( db ) on the vertical axis can be observed the ddk of the " pataka " sequence was analyzed quantitatively through the sound forge 
 7.0 program .
the count of trisyllables per second was performed manually with the 
 auditory and visual waveform support displayed by the program .
average values of oral and vocal fold ddk in dysphonic and nondysphonic women were 
 correlated using the " t student " test and were considered significant when 
 p<0.05 .
subjects were classified by the types of dysphonia , according to behlau , et 
 al .
it 
 was considered primary functional dysphonia when there were no injuries or structural 
 alterations of vocal folds identified by nasolaryngoscopy ; secondary functional 
 dysphonia to anatomical inadequacy , in the presence of structural alterations of vocal 
 folds , such as epidermoid cyst , varicosity , stria sulcus ; organic functional dysphonia , 
 in the presence of edema , leucoplast or bilateral nodules ; and organic dysphonia in 
 cases of gastroesophageal reflux disease or unilateral vocal fold paralysis .
thus , the 
 sample was composed of a participant with primary functional dysphonia , thirteen with 
 secondary functional dysphonia by anatomical inadequacy , seven with organic and 
 functional dysphonia , and three with organic dysphonia , because three women in the 
 sample had no otorhinolaryngologic diagnosis .
the results concerning the oral and vocal fold ddk of the two groups were compared using 
 the " t student " test and are described in table 
 1 .
comparison of oral and vocal fold diadochokinesis ( ddk ) average and standard 
 deviation , between dysphonic and nondysphonic women , in the emissions of " pa , " 
 " ta , " " ka , " " pataka " , " a , " and " i. "
although the findings did not show a statistically significant correlation of oral and 
 vocal fold ddk between the group of women with and without voice disorders ( table 1 ) , some aspects about the performance of 
 diadochokinetic tasks are relevant and should be discussed .
the results showed that the ddk speed , the average time between the vocalizations , the 
 ability to keep constant vocalizations and keeping the intensity of these vocalizations 
 constant did not correlate with the presence of dysphonia ( table 1 ) .
it was expected that no neurological changes related to 
 vocal production would interfere with oral and vocal fold ddk , since for both tasks 
 there was participation of the opening and closing of vocal folds , especially related to 
 " a " and " i " emissions , that involve specifically alternating motions of glottic 
 adduction and abduction , since organic and functional factors may also interfere with 
 the results of the ddk , including not necessarily expressing a disturbance in oral 
 communication .
it was observed that in the " pa " emission , the parameter cvi ( p=0.061 ) , although not 
 statistically significant , showed a tendency for nondysphonic women to keep the 
 vocalizations more constant as compared to the dysphonic group .
this can be explained by 
 the fact that the glottic changes found in dysphonic women , make intensity control 
 difficult , since vocal balance depends on correct coordination between the myoelastic 
 and aerodynamic forces of the larynx ; 

this finding is possibly related to the size of the 
 sample , thus , statistically significant values can be found if the number of subjects 
 were more expressive .
the impairment of phonoarticulatory 
 organs can generate vocal consequences , such as changes in vocal quality , impaired 
 laryngeal mobility , and extrinsic muscle tension of the larynx .
the interference of articulation with phonation shows 
 that such factors might affect the motor performance of these structures and thus , in 
 ddk .
thus , there is a physiological and 
 anatomical inter - connecting of the structures common to phonation and 
 articulation .
thus , individuals who 
 have dysphonia due to a myofunctional alteration that initiates larynx overload could 
 have poorer ddk performance .
some minor structural alterations have morphological characteristics that change the 
 vibration pattern of vocal folds .
therefore , the sulcus vocalis shows 
 an arched vocal fold , and cysts 
 appear on a bulged vocal fold .
this 
 could interfere with the speed of the vocal folds alternating motion rate ( ddk ) . 

leeper , heeneman and reynolds ( 1990 ) reported that , when ddk involves vowel emission , refined 
 control of vocal fold opening and closing is required .
factors such as rigidity and mass can interfere with the fundamental frequency of 
 voice , beyond subglottic 
 pressure , which reflects on vocal intensity .
there are significant differences in the 
 effect of frequency and vocal intensity upon the airflow through the vocal 
 folds .
furthermore , vocal 
 intensity seems to be the primary factor controlling the speed of the ddk and airflow 
 during the production of the vowel " a " . in this study , although no statistically significant correlation was observed , an 
 average frequency of disturbances in the ddk " a " ( ddcjiit ) were higher in dysphonic 
 subjects than in the control group , and this value was approximately doubled .
high 
 frequency values of ddk disturbance may indicate a lower ability to control the vocal 
 folds ' motion during phonation .
vocal fold ddk has not been investigated in detail like 
 an analysis of laryngeal subsystem , as has already occurred with oral ddk .
nondysphonic individuals have appropriate adjustments in their laryngeal mechanism that 
 allows for quick glottal opening and closing during the production of the consonants and 
 vowels of syllables .
this suggests 
 that these adjustments in laryngeal diseases are inadequate , resulting in an increased 
 effort to compensate .
therefore , information obtained with the ddk can be reference for 
 the interpretation of complex tasks .
there is a need for more studies that compare ddk in a control group and in dysphonic 
 individuals , the latter split into distinct groups according to the vocal alteration , 
 thus making it possible to compare diadochokinetic task performance differences in 
 different dysphonias .
although the results do n't indicate any difficulties in oral and laryngeal motor control 
 in the dysphonic group , the major instability in vocal fold ddk in the experimental 
 group should be considered , and studies of this ability in individuals with 
 communication disorders must be intensified .
 the evaluation of oral and vocal fold diadochokinesis ( ddk ) in individuals with voice 
 disorders may contribute to the understanding of factors that affect the balanced 
 vocal production . 
 scientific studies that make use of this assessment tool support 
 the knowledge advance of this area , reflecting the development of more appropriate 
 therapeutic planning.objectiveto compare the results of oral and vocal fold ddk in dysphonic women and in women 
 without vocal disorders . 
 material and methodsfor this study , 28 voice recordings of women from 19 to 54 years old , diagnosed 
 with dysphonia and submitted to a voice assessment from speech pathologist and 
 otorhinolaryngologist , were used . 
 the control group included 30 nondysphonic women 
 evaluated in prior research from normal adults . 
 the analysis parameters like 
 number and duration of emissions , as well as the regularity of the repetition of 
 syllables " pa " , " ta " , " ka " and the vowels " a " and " i , " were provided by the 
 advanced motor speech profile program ( msp ) model-5141 , version-2.5.2 ( kaypentax ) . 
 
 the ddk sequence " pataka " was analyzed quantitatively through the sound forge 7.0 
 program , as well as manually with the audio - visual help of sound waves . 
 average 
 values of oral and vocal fold ddk dysphonic and nondysphonic women were compared 
 using the " t student " test and were considered significant when p<0.05 . 
 resultsthe findings showed no significant differences between populations ; however , the 
 coefficient of variation of period ( cvp ) and jitter of period ( jittp ) average of 
 the " ka , " " a " and " i " emissions , respectively , were higher in dysphonic women 
 ( cvp=10.42% , 12.79% , 12.05% ; jittp=2.05% , 6.05% , 3.63% ) compared to the control 
 group ( cvp=8.86% ; 10.95% , 11.20% ; jittp=1.82% , 2.98% , 3.15% ) . 
 conclusionalthough the results do not indicate any difficulties in oral and laryngeal motor 
 control in the dysphonic group , the largest instability in vocal fold ddk in the 
 experimental group should be considered , and studies of this ability in 
 individuals with communication disorders must be intensified . 