Journal ofNeurology, Neurosurgery, and Psychiatry 1991;54:1093-1098 1093 J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.54.12.1093 on 1 December 1991. Downloaded from Articulatory deficits in Parkinsonian dysarthria: an acoustic analysis

H Ackermann, W Ziegler

Abstract with increased articulatory effort."8 This raises Twelve patients with idiopathic Parkin- the question of how far patients with PD are son's disease had acoustic speech analysis able to produce such extra effort, suggesting of sentence utterances to provide infor- that sentence utterances rather than simple mation on speech tempo and accuracy of repetitive oral movements ought to be used in articulation. As a measure of rate of investigating Parkinsonian dysarthria. speech the duration of opening-closing We used acoustic data for the description of movements during articulation was hypokinesia and bradykinesia within the determined from speech wave variables. speech motor system of patients with PD. The intensity of sound emission during Acoustic analysis was based on variables articulatory closure as required for stop characterising the sound wave emitted during consonant production, for example, /p/, speaking and allows limited inferences about /t/, /k/, was used as an index of the degree articulatory features. A sentence repetition of closure. Speech tempo was not signifi- paradigm was used to approximate most closely cantly different from normal. The patien- the conditions ofnatural speech to ascertain the ts, however, had a reduced capacity of effectiveness of certain linguistic constraints, completing articulatory occlusion. This that is, sentence accent, on speech movements was interpreted as reflecting a reduction in Parkinsonian dysarthria. in movement amplitude of the articulators. Articulatory "undershoot" was not uniform but influenced by lin- Subjects and methods guistic demands in that the closures Subjects associated with a stressed syllable were Twelve patients with idiopathic Parkinson's performed at the expense of unstressed disease (seven men, five women, 47 to 76 years, ones. Furthermore, switching between median 62 years) participated in this study. opening and closing movements of the The clinical data are presented in the table. All articulators in sentence production patients were on drug therapy; none had seemed undisturbed. These results positive signs of dementia at psychopatho- indicate that motor planning of speech logical examination. The range ofoverall motor http://jnnp.bmj.com/ differs from arm movement control. impairment at the time of speech evaluation extended from slight akinetic-rigid states to severe disability. Two patients suffered from The motor deficits of hypokinesia (reduced levodopa induced on/off fluctuations; in both, range of simple limb movements with con- the speech recordings were obtained during the sequent target undershooting) and bradykin- offstate. The control group included 12 "young esia (slowness of movements) are characteristic normals" (seven men, five women, 19 to 35

of Parkinson's disease (PD).' In speech, per- years, median 29 years) and 12 "elderly nor- on October 2, 2021 by guest. Protected copyright. ceptual as well as acoustic signs of hypokinesia mals" (eight men, four women, 42 to 64 years, in articulation have been widely presumed.2" median 53 years). Moreover, kinematic analyses have provided Department of direct evidence of reduced and slowed Speech examination Neurology, University articulatory movements particularly of the lips All subjects underwent speech examination in a of Tiibingen, Germany and the jaw in patients with PD.'2-'7 Studies of sound attenuated room. Recordings were made H Ackermann limb motor control have shown not only slow- on a Nagra IV S tape recorder with a Senn- Clinical in Neuropsychology ness of single movements but also a delay heiser microphone positioned about 20 cm in Group, Municipal executing complex motor sequences due to front of the subject. Speech materials included Hospital, problems in "switching" from one motor sentences of the form "Ich habe /geCVCe/ Bogenhausen, Munich, to another. The in ("I have heard .. .") with C = Germany programme impairment gehort" /p/, /t/, W Ziegler running motor programmes seems to be closely /k/ and V = /i/, /y/, /u/, /a/. The formula of clinical together with the lists of consonants Correspondence to: related to the degree bradykinesia.' /geCVCe/ Dr Ackermann, Department Whether this principle applies to speech con- and vowels to substitute for C and V enabled of Neurology, University of Tubingen, Hoppe-Seyler-Str trol as well is not known. the use of 12 target words-for example, 3, 7400 Tubingen, Germany Prosodic features such as linguistic or "getite", "gepype", "gekuke". These "words" Received 19 November 1990 emotional stress influence speech movements represent regular phonological forms of stan- and in final revised form 10 April 1991. in sentence production. In normal speech the dard German, so that to a certain extent the Accepted 26 April 1991 production of stressed syllables is associated sentences fulfil natural speech demands. The 1094 Ackermann, Ziegler J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.54.12.1093 on 1 December 1991. Downloaded from Table Clinical data ofpatients with Parkinson's disease

Duration Motor signs (limbs) of disease CT-scan Patient Age Sex (years) akinesia rigidity tremor Depression (atrophy) Medication 1 47 m 12 (+) - - - - Id,am 2 60 m 4 (+) - + - (+) ld,ac 3 69 f 1 + (+) - - - Id 4 63 m 5 (+) (I)- (±) - ld,am 5 73 f 10 ( ) (+) - - (+) Id,am,br 6 58 f 10 (+) (+) (+) - - ld,br,ac 7 57 m 9 + + (+) (I)(+) Id,br 8 71 m 2 + (+) + - - ac 9 66 m 12 + (+) - - - Id,br 10 52 f 8 + (+) - - - ld,br 11 60 f 6 + + + - - - ld,br,ac 12 76 m 13 + + + + (+) (+) ld,br Id = levodopa, br = bromocriptine, am amantadine, ac = anticholinergic drugs- = missing, (±) = slight, + = moderate, + + = distinct.

test sentences were read by the examiner in a reduced to the level of the tape noise, whereas quasi-randomised order and repeated by the vocal tract opening for a vowel is associated subjects at a suitable rate and loudness level. with an intensity peak. Incomplete closure The entire test, consisting of 12 test sentences, resulting from reduced extension of man- was run twice by all speakers. dibular, labial, or lingual movements or from reduced occlusive force may be expected to Perceptual evaluation result in an increase of sound pressure during To obtain perceptual judgments the patients' stop realisation (as seen in the lower half of recordings were evaluated by five experienced figure 1) as acoustic energy is still emitted from speech therapists. The evaluation protocol the mouth.'9 SPL contours allow calculation of included seven-point ratings of variables such syllable durations and of the amount of sound as a patient's overall articulatory and vocal emission during closure, and moreover reflect impairment and his or her speech tempo. dynamic aspects of sound pressure change during closing and opening movements. Acoustic evaluation Mean syllable duration (MSD) The dura- Sound pressure level (SPL) contours Speech tions of four syllables of each test utterance signals were digitised at a sampling rate of were measured: /be/, /ge/, /CV/, /Ce/ (such as 20 kHz after low-pass filtering at 9 kHz and /be/, /ge/, /pi/, /pe/ in the example of figure 1). were fed into a LSI 11/73 for further process- Syllable duration was determined by measur- ing. Sound pressure level (SPL) contours were ing the time period ofa syllabic peak in the SPL calculated for each of the 24 sentences. The contour. Specifically the duration of a syllable SPL was determined every 3-2 ms over a 1-2-6 was defined as the time interval between the two ms window and the resulting contour was points where the SPL contour crossed the 5% smoothed by a 30 Hz low-pass filter. Figure 1 threshold between the SPL maximum corres- provides examples for the test sentence "Ich ponding to the syllabic peak and the minima habe gepipe gehort" as spoken by a normal left and right ofit.'9 The four syllable durations http://jnnp.bmj.com/ subject and a patient with PD. During com- of a sentence were averaged and the median plete closure (as required for the stop conson- value ofthe 24 test utterances ofthe subject was ant sequence /b/, /g/, /p/, /p/, /g/ of the test calculated. We called this measure the mean sentence of figure 1) intensity is normally syllable duration (MSD). As the syllables used in the computation of MSD consisted of a stop consonant and a vowel each, MSD may be Figure 1 Sound pressure beig ap i peg level (SPL) contours of considered here as reflecting the time interval of test sentence "Ich habe an opening-closing cycle. By virtue of its on October 2, 2021 by guest. Protected copyright. gepipe gehort" obtained definition MSD provides an index of speech from normal speaker (upper half) andfrom tempo which is unaffected by pausing, syllable patient with Parkinson's iteration, or by difficulties in word-finding or disease (lower half). speech initiation problems that may also be Trace at top shows in oscillogram of test sentence present PD.20 as spoken by normal Intensity during closure (IDC) For the two subject. Vertical lines stop consonants preceding and following the mark syllable boundaries, (stressed) target vowel of a test word triangle indicates onset of (for stressed vowel. Above instance the two /p/s in the example offigure 1) oscillogram part of test intensity minima were computed. As men- sentence "ich habe gepipe tioned above this variable measures the acous- gehort" is depicted. Reversed "e" represents tic quality of stop consonant production and is phonetic symbol denoting particularly sensitive to incompleteness of short and centralised e- closure sound. (undershooting). Median values of SPL (dB) intensity minima were determined over all 24 sentences of a subject for each of the pre- and post-stressed closures, respectively. We called the resulting measure the intensity during Time (s) *. closure (IDC). Articulatory deficits in Parkinsonian dysarthria: an acoustic analysis 1095 J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.54.12.1093 on 1 December 1991. Downloaded from

Figure 2 Perceptual considered normal and three were more severe- judgments offive speech Mean rating scores (5 Listeners) pathologistsfor patients' 0 = Normal ly dysarthric (numbers 10, 11, 12). Impairment overall impairment of 6 = Severe of vocal variables-for example, vocal inten- voice (abscissa) and 4- sity, pitch, and intonation-was judged more articulation (ordinate) c 0 given in mean rating 0 severe than articulatory deficits, although the scores. .3 difference was only marginally significant (Wil- 0 coxon, p < 0.05). Considering articulation 2- 0 alone, three patients were judged as undistur- bed and two further patients obtained mean *0 0 0 scores lower than 1. 0 *0 0 Speech tempo The mean syllable durations 0- obtained in the two normal groups and in the patients with PD respectively are shown in 0 2 4 figure 3. Nonparametric testing (Mann- Voice Whitney) revealed that the young normal group spoke significantly faster than the elderly normal group (p < 0-01). No significant dif- Transition quotient (TQ) The period of full ferences were obtained between the patients opening during vowel production may with with PD, however, and either the young nor- some justification be considered a steady state, mals or the elderly normals (p > 0-1). The two characterised by temporarily stable acoustic clinically most impaired patients (numbers 11 conditions, in contrast with the intervals of and 12 in the table) presented with increased opening and closing where acoustic conditions MSD, whereas three further patients were are subject to fast changes. The relative slightly faster than the elderly normals, show- durations of these periods within a consonant- ing mean syllable durations within the lower vowel-consonant cycle contain dynamic infor- range ofthe young normals. In accordance with mation on the underlying movements. In these measurements, perceptual evaluation particular, the relative duration of the steady indicated slowed speech in the former two and state interval may be considered an index ofthe accelerated speech in the latter three patients. time period when the switch between the No correlation between degree of severity as opening and closing gestures occurs. We con- judged by perceptual evaluation and mean sidered the period between the 95% thresholds syllable duration could be detected (Spearman, of the rising and falling SPL contour the r = 026, p > 0-1). steady-state portion and the remainder of the Articulatory precision Unlike mean syllable full syllabic cycle (the two 5%-95% slopes) as duration, intensity during closure (IDC) was the movement portion. A transition quotient substantially disturbed in the patients as a (TQ) was computed by dividing the movement group. Figure 4 shows that the IDC values of portion of a syllable by the full syllable dura- the post-stressed consonant were significantly tion. This quantity was determined for the increased in the patients compared with either target CV syllable in each sentence and again ofthe two normal groups. A significant correla- the median value over all utterances ofa subject tion between perceived severity of overall was used to characterise his or her perfor- articulatory impairment and IDC was found mance. r = (Spearman, 0 64, p < 0-05). Whereas the http://jnnp.bmj.com/ patients who were judged as having little or no Results Perceptual evaluation Figure 2 presents the results ofperceptual judgments ofthe patients' *** (P<0-001) overall impairment of voice (abscissa) and ** (p<0-01) I articulation (ordinate). The data reveal that 0 L- most cases were judged to be of mild to 0 on October 2, 2021 by guest. Protected copyright. moderate severity. One patient (number 1) was 3 C 0 0 Figure 3 Mean syllable NS durations (96 syllables in NS 0 each subject) ofyoung ,- normals (YN), elderly 400- NS o normals (EN), and 0 c 0( patients with Parkinson's 0 8 disease (PD). Durations -cn300- I are shown on logarithmic 0 scale. ** (p<0*O1) 0 EN PD .2 r:rmnI 0 a Figure 4 Intensity during closure (IDC)-that is, i O minimal sound pressure level (SPL) during stop consonant production-in young normals ( YN), elderly §3 normals (EN), andpatients with Parkinson's disease (PD). For each subject median value determinedfrom 100 ,---- post-stressed closures over all 24 sentences is depicted, YN EN PD reflecting articulatory accuracy ofstop consonant Group production. 1096 Ackermann, Ziegler J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.54.12.1093 on 1 December 1991. Downloaded from 40- Figure 5 Difference of Discussion intensity during closure ** (p<0-o1) Speech motor deficits can be described on the (IDC) between stops basis of perceptual, acoustic, or physiological preceding andfollowing 30 stressed target vowel in **(pParkinsonism of the post-stressed aind that of the stressed and values two times as high as the maximum syllable in the three es xcperimental groups. In obtained in their patients, although jaw almost all normal speak;ers the IDC:values were sedstha InCthuessrese movement amplitudes were among the higher in the post-stres measures that showed the highest group dif- position. This corresp onds to expectations as ferences between the patients and the normal the realisation of stress is generally assumed to group in their study. Not unexpectedly there- be associated with an increase in muscular fore there is a notoriously low correlation activity.2' In the patie between movement data and perceived degrees differences were positis ve, suggestingsuggstin theirte sen- of dysarthric** impairment.* 26 Moreover, the tence productions folllowed[owedaa normal accenten- of movements pattern. The resulting difference values were recording speech by physio- a i the atients relative to logical techniques usually requires high significantly enhanced amount of cooperation of the subject if reliable the normal subjects, wh :eichmaymean trat their data are to be produced, a precondition that efforts to produce senteortincaccentwerieratith often cannot be met in many subjects with expense of an overproI neurological illness. Further, these techniques of the post-stressed sto Consutationatortsonante.deteriationofthepotentially disturb natural speech production, Transition quotient which imposes particular on the transition quotient (TQ Computatednosioniofich limitations tievealednotsigniant analysis of more complex utterances like sen- differences between pai PD tences. This may be one reason why parametric mal speakers (figure 6).' Tiens wih andeynor-to thmerewsaotendeny studies of articulation in Parkinsonism have so http://jnnp.bmj.com/ enhanced movement tm bothard winheder far focused on elementary speech tasks-for normals and patients example, single word production or rapid syl- younger se however,..howitt normals. Thes differences,compafferedes, lable were not significant.' ro the extent that the repetition (diadochokinesis). Although ybe an diadochokinesis seems to predict the overall complement of TQ ma) considered index2adequacy of speech in dysarthria fairly well,2 of the faculty of sv vitchingitching betweenbetwing)twotou the syllable repetition. tasks commonly movement directions (c employed in the measurement of diadochokin- patienig exan ing) ouere on October 2, 2021 by guest. Protected copyright. results show that the 1 patsienthsrexaminedhe etic rates have the disadvantage of differing had no particular probl from natural speech in terms of the underlying Figure 6 Transition motor organisation. quotients (TQ) -that is, NS A way to circumvent the limitations of movement portion of NS physiological assessment techniques and, at syllable divided by full 0.9- syllable duration-in the same time, obtain objective and quanti- young normals (YN), tative data, is provided by acoustic analyses elderly normals (EN), c - 8 0 of the speech wave. Although a one-to-one and patients with 0 0 Parkinson's disease (PD). correspondence between acoustic measures of Median values over all c a I3 speech sounds and the corresponding speech utterances of each subject .2 0-8- 0 movements does not exist, certain inferences are given. 8 concerning disturbed motor patterns may - o nevertheless be drawn from acoustic data if speech tasks are appropriately designed. Most 0-7- o 0 importantly, acoustically verified deviations from a given target may be considered to reflect relevant aspects of disturbed speech rather YN EN PD than functionally irrelevant idiosyncracies of Group articulation. Articulatory deficits in Parkinsonian dysarthria: an acoustic analysis 1097 J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.54.12.1093 on 1 December 1991. Downloaded from In accordance with earlier studies' our the maintenance ofa normal rate at the expense patients displayed on average slightly more of articulatory precision is far from universal. pronounced phonatory than articulatory dis- On the contrary, most dysarthric syndromes turbances, as far as clinical-perceptual ratings are associated with slowed speech and, at the are concerned. Logemann and Fisher sugges- same time, undershooting articulation.5 The ted a progressive involvement of speech organs faculty of maintaining a normal syllabic rate in PD, beginning at the laryngeal level and therefore seems characteristic of the Parkin- proceeding in the oral direction.7 An alternative sonian type of dysarthria. explanation would be that the laryngeal Yet, following our data and also our earlier apparatus is more vulnerable to the patho- observations, the syndrome of Parkinsonian physiological processes underlying PD, mean- dysarthria is by no means homogeneous with ing that even very mild motor disturbances respect to speech rate. Seguier et al observed have clearly audible consequences. Finally, slowed speech in 5% of their patients.29 In our impairment of respiratory support may con- sample, two patients had increased syllable tribute to phonatory problems in patients with durations, though the observed increase must PD. be considered fairly mild when compared to Our main acoustic finding was a relative spastic dysarthria of similar severity.34 Both preservation of speech tempo and, at the same subgroups with either increased or decreased time, a reduction of articulatory precision in MSD presented with hypometria in terms of stop consonant production. A normal or even incompleteness of closure. Possibly the two increased rate ofspeech has often been reported different types reflect consecutive stages in the in PD27"' and is considered specific for this development of Parkinsonian dysarthria or disorder by some authors.529 At first sight the different degrees of impairment, respectively. finding of a normal or even increased speech According to the clinical impressions and per- tempo seems to be incompatible with the ceptual judgments of experts the two patients concept of bradykinesia, which is a well known with increased MSD were most severely affec- feature of limb akinesia in PD' and has been ted, with severe phonatory deficits in addition found in the speech motor system as well."7 Yet, to their articulation problems. At this severity the observation of normal or reduced syllable the maintenance ofa normal syllabic rate at the durations does not necessarily mean that the expense of articulatory precision might have underlying articulatory movements were of a led to completely unintelligible articulation, normal or even increased velocity. The fact that causing the patients to slow their speech. An articulatory closure for stop consonant produc- alternative explanation would be that a tion was obviously incomplete in some of the critically reduced velocity of laryngeal abduc- patients suggests that these patients performed tions and adductions forced the patients to articulatory movements of reduced amplitude. lower their syllabic rate. Despite possible bradykinesia they seem to Articulatory imprecision was not uniformly have produced normal syllabic rates at the distributed among the stop consonants of a expense of movement excursion. This is in sentence but rather varied systematically with agreement with the findings of Forrest et al of the sentence accent. Comparison of closures of consistent reductions in both peak velocity and the stressed and the post-stressed syllable of a amplitude of mandibular and labial opening sentence showed normal or almost normal

gestures at normal movement times.'617 performance in the stressed position but an http://jnnp.bmj.com/ This trade off between tempo and overproportionately reduced realisation in the articulatory precision is made possible by the post-accent position. In other words, hypo- fact that reduced articulatory precision may kinesia affects successive articulatory gestures still be compatible with the requirements of ofan utterance to different degrees. Obviously, intelligible speech. In this respect speech is the patients with PD were forced by the different from other motor acts, like grasping, linguistic status of the stressed CV-syllable to where a similar trade off cannot be made with- raise more "effort" in the closing movement. out compromising the requirements of the Thus inappropriate "energising" of agonist on October 2, 2021 by guest. Protected copyright. motor task. A task more similar to speech muscle activity and inadequate "scaling" of would be handwriting, with the typical symp- agonist burst size to task requirements3' 32 are tom of micrographia being observable in PD. not universal features of Parkinsonian motor Micrographia resembles hypokinetic speech in deficits. With respect to complex speech motor that smaller movement excursions compensate patterns patients with PD seem to be capable of for the inability to execute high velocity appropriate "energising" and "scaling" of one strokes.0 Thus the results of speech analysis- elementary movement at the expense ofothers, are not incompatible with the concept of dependent upon linguistic demands. bradykinesia as outlined for limb motor Clinical and experimental data indicate that control, emphasising the slowing down of patients with PD have difficulties in "running" individual movements due to inadequate a sequence of motor programmes linked to- "energising" and "scaling" of initial agonist gether within a complex motor plan-that is, in muscle activity in relation to functional "switching" from one motor programme to the demands.3' 32 next one."' For instance, when performing a The tempo-precision trade off is-well known sequence of two simple movements patients from normal speech, where an increase in show a prolongation ofthe interval between the speech rate is usually achieved by a reduction of two elementary- actions. Thus in complex movement amplitudes rather than by speeding movements, there is an extra delay in addition up the movements themselves." In dysarthria to the increased slowness of the individual 1098 Ackermann, Ziegler J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.54.12.1093 on 1 December 1991. Downloaded from movements.6'" Similarly, when drawing tri- tion, and glottal-supraglottal coordination. In: McNeil MR, Rosenbek JC, Aronson AE, eds. The dysarthrias: angles and squares the pauses at the angles are physiology, acoustics, perception, management. San Diego: increased.8 Connor et al showed that isolated College Hill, 1984:101-30. 12 Hirose H, Kiritani S, Ushijima T, Yoshioka H, Sawashima syllables and syllables produced within repeti- M. Patterns of dysarthric movements in patients with tion trains do not differ significantly in terms of Parkinsonism. Folia phoniat 1981;33:204-15. 13 Hirose H, Kiritani S, Sawashimna M. Velocity ofarticulatory acoustic variables.'0 As repetitive syllable movements in normal and dysarthric subjects. Folia production should have greater demands on phoniat 1982;34:210-5. 14 Hirose H. Pathophysiology of motor speech disorders motor planning than isolated syllables these (dysarthria). Folia phoniat 1986;38:61-88. findings seem contrary to planning 15 Hunker CJ, Abbs JH, Barlow SM. The relationship between deficits in parkinsonian rigidity and hypokinesia in the orofacial speech motor control of patients with PD. system: a quantitative analysis. Neurology 1982;32: Syllable repetitions, however, may differ from 749-54. 16 Connor NP, Abbs JH, Cole KJ, Gracco VL. Parkinsonian connected speech insofar as an iteration of the deficits in serial multiarticulate movements for speech. motor programme or highly automatised Brain 1989;112:997-1009. 17 Forrest K, Weismer G, Turner GS. Kinematic, acoustic, processes may take over. Our analysis of the and perceptual analyses ofconnected speech produced by open close Parkinsonian and normal geriatric adults. J Acoust Soc Am transitions in sentence production 1989;85:2608-22. showed no deviations for the utterances of the 18 Sussman HM, MacNeilage PF. Motor unit correlates of patients as stress: preliminary observations. J Acoust Soc Am 1978; transition quotients were within 64:338-40. normal limits. One might consider this result as 19 Ziegler W, von Cramon D. Spastic dysarthria after acquired brain injury: an acoustic study. Brit J Dis Comm 1986; being in contrast with the observations of 21:173-87. Benecke et al36" and Berardelli et al8 In these 20 Ackermann H, Ziegler W. Die Dysarthrophonie des Parkin- paradigms, however, the single movements are son-Syndroms. Fortschr Neurol Psychiat 1989;57:149-60. 21 Ostry DJ, Keller E, Parush A. Similarities in the control of obviously governed by independent motor the speech articulators and the limbs: kinematics oftongue programmes.39 In contrast, there is some lin- dorsum movement in speech. J Exp Psychol Human Percept Perform 1983;9:622-36. guistic evidence that complex articulation 22 Zyski BJ, Weisiger BE. Identification of dysarthria types patterns underlying sentence based on perceptual analysis. J Commun Disord 1987; utterances are 20:367-78. under the control of a single "articulatory 23 Kent R, Netsell R. A case study of an ataxic dysarthric: plan" structured by cineradiographic and spectrographic observations. J suprasegmental-that is, Speech Hear Dis 1975;40:115-34. prosodic-features."' Therefore, the concaten- 24 Schonle PW, Grabe K, Wenig P, Hohne J, Schrader J, ation of elementary articulations might not be Conrad B. Electromagnetic articulography: use of alter- nating magnetic fields for tracking movements ofmultiple afflicted by the pathophysiological mechanisms points inside and outside the vocal tract. Brain Lang outlined by Benecke et al' " and Berardelli 1987;31:26-35. 25 Forrest K, Weismer G, Adams S. Statistical comparison of et al.38 movement amplitudes from groupings of normal geriatric speakers. J Speech Hear Res 1990;33:386-9. 26 Caligiuri M. The influence of speaking rate on articulatory All acoustic work was carried out by the Neurophonetics Group hypokinesia in parkinsonian dysarthria. Brain Lang 1989; at the Max Planck Institute for Psychiatry, Munich, under the 36:493-502. guidance of W Ziegler. We thank E Hartmann, P Hoole, and I 27 Alajouanine T, Sabouraud 0, Gremy F. Etude oscillo- Wiesner for their cooperation. Most of the patients were kindly graphique de la parole dans la maladie de Parkinson: effets referred to us by W H Oertel, Department of Neurology, precoces de la coagulation pallidale. Rev Franc Etudes Clin Klinikum Grofihadern, University (LMU) of Munich. This Biol 1964;9:41 1-9. work was supported by a BMFT grant. 28 Ludlow CL, Connor NP, Bassich CJ. Speech timing in Parkinson's and Huntington's disease. Brain Lang 1987; 32:195-214. 29 Seguier N, Spira A, Dordain M, Lazar P, Chevrie-Muller C. Etude de les relations entre les troubles de la parole et les autres manifestations cliniques dans la maladie de 1 Marsden CD. Slowness ofmovement in Parkinson's disease. Parkinson. Folia phoniat 1974;26:108-26. Movement Dis 1989;4:S26-S37 (suppl 1). 30 Sanes JN, Evarts EV. Psychomotor performance in Parkin-

2 Canter GJ. Speech characteristics of patients with Parkin- son's disease. In: Delwaide PJ, Agnoli A, eds. Clinical http://jnnp.bmj.com/ son's disease. III. Articulation, diadochokinesis, and neurophysiology in parkinsonism. Amsterdam: Elsevier, overall speech adequacy. J Speech Hear Dis 1965;30: 1985:117-32. 217-24. 31 Hallett M, Khoshbin S. A physiological mechanism of 3 Darley FL, Aronson AE, Brown JR. Differential diagnostic bradykinesia. Brain 1980;103:301-14. patterns ofdysarthria. J Speech Hear Res 1969;12:246-69. 32 Berardelli A, Dick JPR, Rothwell JC, Day BL, Marsden 4 Darley FL, Aronson AE, Brown JR. Clusters of deviant CD. Scaling of the size of the first agonist EMG burst speech dimensions in the dysarthrias. J Speech Hear Res during rapid wrist movements in patients with Parkin- 1969;12:462-96. son's disease. J Neurol Neurosurg Psychiat 1986;49: 5 Darley FL, Aronson AE, Brown JR. Motor speech disorders. 1273-9. London: Saunders, 1975. 33 Kent RD. The segmental organization of speech. In:

6 Logemann JA, Fisher HB, Boshes B, Blonsky ER. McNeilage PF, ed. The production of speech. New York: on October 2, 2021 by guest. Protected copyright. Frequency and cooccurrence ofvocal tract dysfunctions in Springer, 1983. the speech ofa large sample ofParkinson patients. JSpeech 34 Ziegler W, Hartmann E, Hoole P, von Cramon D. Akustische Hear Dis 1978;43:47-57. Dimensionen dysarthrischer St6rungsmerkmale. Munchen: 7 Logemann JA, Fisher HB. Vocal tract control in Parkinson's GSF, 1990. disease: phonetic feature analysis of misarticulation. J 35 Marsden CD. The mysterious motor function of the basal Speech Hear Dis 1981;46:348-52. ganglia. Neurology 1982;32:514-39. 8 Ludlow CL, Bassich CJ. Relationships between perceptual 36 Benecke R, Rothwell JC, Dick JPR, Day BL, Marsden CD. ratings and acoustic measures of hypokinetic speech. In: Disturbance of sequential movements in patients with McNeil MR, Rosenbek JC, Aronson AE, eds. The dysar- Parkinson's disease. Brain 1987;110:361-79. thrias: physiology, acoustics, perception, management. San 37 Benecke R, Rothwell JC, Dick JPR, Day BL, Marsden CD. Diego: College Hill, 1984:163-95. Simple and complex movements off and on treatment in 9 Ludlow CL, Bassich CJ. The results of acoustic and patients with Parkinson's disease. J Neurol Neurosurg perceptual assessment of two types of dysarthria. In: Psychiat 1987;50:296-303. McNeil MR, Rosenbek JC, Aronson AE, eds. The dysar- 38 Berardelli A, Accornero N, Argenta M, Meco G, Manfredi thrias: physiology, acoustics, perception, management. San M. Fast complex arm movements in Parkinson's disease. Diego: College Hill, 1984:121-53. JNeurol Neurosurg Psychiat 1986;49:1146-9. 10 Connor NP, Ludlow CL, Schulz GM. Stop consonant 39 Benecke R, Rothwell JC, Day BL, Dick JPR, Marsden CD. production in isolated and repeated syllables in Parkin- Motor strategies involved in the performanceofsequential son's disease. Neuropsychologia 1989;27:829-38. movements. Exp Brain Res 1986;63:585-95. 11 Weismer G. Articulatory characteristics of parkinsonian 40 Levelt WJM. Speaking. From intention to articulation. dysarthria: segmental and phrase-level timing, spirantiza- London: MIT Press, 1989.