Predictive measures of speech proficiency in cerebral palsied speakers

385

PREDXCTXVE

SURESOFSFEECHPRQFICIENCYIN rth &de, N.S. W., Australia

thiversity.

Traditionally,

?$fgo. North Dakota

the 8cppacb to th

for the cerebralpalsied individualhas been to select an area of difficulty,such ti articulationor voice, and attemptto improve the ability of the individualin that area, However, there remainsthe possibilitythat other proceduresmay improvethe o-feral1communicativeability of the child, and this would suggest the need for predictivemeasuresof speech proficiencyso thattherapymay be aim& more specificallyat this overallgoal of improvement of speech proficiency. The literaturepetining to predictive ~MMWW in the speech of the cerebralpalsied is practicallynonexistent.Burgi and Mathe~ (19%) in th& investi on using cerebralpalsied ape&&sfound that t;hsFci8 a pxedictivclradrtlonshipbatween the numberrofarticulatoryet~ors

and int@IIigibiIity. Although this finding is not particularly surprising, it is po&bIy the onIy p&ktivs measureof th8 sph of the wbral palsi~& Other maearchin the area haoattempt&o dlff@rentiate the speechcharacteristics of the spat& and athatoidsubclass~ of thecerebralpalsiedpopulationand it is po4blo that some of th@aeatudicsmay providesomespeculativeinformation on the pareme@mwhich co~~4atewith the overall speech p-flciency of this population. In the cerIier stucllesby Rutherford (1944) and L&h and Steer ( WB),listcrrner jud#ementsof the parnmeocrsof rate, pitch, loudness+articulation, and intelligibility were esscssgd. In later research using rating scales, AdQsu

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StacaUnivaiidcy, Faqo, NaUalhkota

inc.,1960 !I2 Vmddilc AWL, New Yak, NY lQo17

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386

W. M. CLARKE and H. R. HOOPS

Han-mill and Myers ( 1968) and Hammill and Irwin (l%S) made

subjccti~e

measures of articulator-yefficiency arrd general speech proficiency. It would appear, therefore, that many spastic and athetoid subclasses of predkting the speech proficiency of be reinforced further by the clinical findings of Wolfe ( 1950) who athetoid speakers have a slower speech rate because of the disturbance and this would suggest a direct relationship parameter and the physical disability. The present study attempted to investigate the relationship betwexxtjud speech proficiency of cerebral palsied speakers and the following quantitative speech parameters:

1:the number of articulatory errors; 2. 3. 4. 5. 6. 7.

the intelligibility of the speech of the cerebralpalsied; mua vocal fundamental frequency; variation of vocal fundamental frequency; rne;m speech-sound pressure level; vartation of speech-sound pressure level; word-per-minute speech rate.

Secondarily the study investigated the differences in the speech of the spastic and atbetoid populations in terms of the parameters listed above. Method Subjects The subject sample consisted of 50 children with congenital cerexal palsy selected from a number of treatment centers in Detroit and surrounding areas* The diagnosis of congenital cerebral palsy was determined from th: medical record of each child. The subclasses of athetoidor spastic were also determined from the medical record and this was noted for each subject. Criteria for,selection were that each child cl;ruld spontaneously read the Arst level passage of the Durrell Reading Analysrs Test and that they could respond to all freqr en&s of an auciiomnetric screening test presented at 20 dB at frequencies of 500, NOQ,and 2oOoHz. The sample was made up of 25 males and 25 females with a mean age of 11 yrs, 3 mo. The age rangewas Qom 6 yrs, 4 mo to 19 yr. Furtherdqrcriptivedata that were obtained from the records of these children indicatedthat the mean readinglevel was approximatelygrade 2 level and the average intelhgence of the group was in the range of slow learner to borderline retarded.

ML

PALSIED SPBAKERS

387

of 20 athetoid and 30 spastic subjects and these mateiy equivalent far age, sex ratios, and reading levels.

room and seated in a comfortable of a helmet with an attached 12&t. mouth-to-microphone subject ws utilized for t.hp to the subjects and time was allowed to for pronunciation and identification of the ator subjects read the speech sample at a consistent recording level. Reading Analysis test passage (1853), one List of the Harvard PhoneticaRy Balanced Word Lists, and the art Form Articulation Test ( 1960). at the reading passage were randomly ordered and presented ly produced sound-treated listening room with an ambient vel of Xl dB measured on the C weighting scale. The output level was It listening levelfor all positions of the room as specified between 72 dB and 78 dB SPL. The 38 judges were considered inexperienced and came from introductory pathology courses. The judges were instructed at they were about to ers, all of whom hadcerebralpalsy. The was thenplayedt.1the t they would have some idea of the range q.>f speaker ability. The tape was played a second time and the judges were instructed to listen to the 50 and to rate each speaker on a 1 to 7 equal appearing interval scale of h speaker.An analysis of the inrerjudge reliability was rtnan_Brown prediction formula and this yielded the Anding indicated a very hi tt reliability between the judges and it assumed that the diff~nces between the mean ratings is part of the error of measurement. The 50 recordings of the PB words were randomly ordered and divided into three sections. Three groups of three listeners, all of whom were majors in speech pathology, listened in an acoustically treated sound room to the recordings of the subjects. The listening conditions were the same as those described earlier, The listeners were provided with response sheets and directed to write down the word that hey thoughtthe subjectsaid. The recordingof one subject was played to all three groups of listen- and a Chi-squareanalysis was used to test the intergroup reliability of the judges. As there was no significant

W. M. CLARKEand H. R. HOOPS

388

difference between the responces of the three groupsof listeners, the reliabilityof the judges was considered to se satisfactory. Fifty recordings of the respc nses to the Templin Darley ArticulationTest were uate students in presented in an acoustically treated sound room to nine to s;Jeechpathology. The listeners were directed to mark th be misarticulated. instrumental

Procedure

lOO@Hztone was recordlsd 12 in. from the surface of a speaker wing the same input level as that used for the recording of the subjects. The sound er and pressure level of this tone was measured at the surface of the s calibration of the statistical distribution analyser was achieved by adjustingthe level of the recorded tone at the outputof the tape recorderand the power level recorder. This calibration produced a known intensity in an appropriatechannel of the statistical distribution analyser. The 50 recordings of the reading passsg~ were supplied to the power level recorder and the mean speech-soundpressure level and ;rhestandard deviation of sound pressure level was calculated for each subject from the readings of the statistical distribution analyser. Enconjunction with this analysis a graphic trace was made on the power level recorder. The word-per-minute reading rate wa:i subsequently calculated from these tracings. The third sentence of the reading passage was supplied to a Light Writing Oscillogray?h.A graphic trace was made of the 50 subjects and period values were obtaned on a wave-by-wave basis. Mean fundamental frequency and fundarnental frequency variation were computed from these period values. A

Results The mean vak

of the various speech parameters for the total subject sample

are shown in Table 1. The mean number of articulatory errors was calculated firsm the number of errors each subject made on the articulation test. The mean nu articulatory errors was calculated to be 15.% with a range of B-50 errors.

TABLE 1 Summaryof the means of the speech perametcr?; for cerebralpalsied subjects (N = ZiQ). Numberof ArtkulatoryErrors Intelligibility(%) Speech Proficiency Rating (I-7 Scale) Speech Sound kssure Level (OR) Fundamental Frequency[Hz: Word-per-minutereading rate

1S.W 41,75 4.07 74.24 235.19 71.38

Bd4LPAlstED SPBAKEbtS

389

wlatedkom the listener responses eve1 of inteSIigibility was enqc4~t rating scale e of LOS to 643 on the

range of frequencies for the total

parameters in this study were subjected to a to determine if any of these variables were ciency ratings. The correlation matrix in Table 2 Wween number of articulatory errors, intel&&ng rate with speech proficiency. The ysis as shown in Table 3, resulted in a multiple R of 0.9161 with the largest proportions of beta weights coming from the variables; number of articulatory errors, intelligibility, and word-per-minute reading rate. The F ratio values for these three variables -uere significant at the 0.01. lever a significant degree of predictability between the dependent proficiency ratings and the independent variables: number of , intelligibility , and word pep minu’tereading rate. The means of the various parameters, as shown in Table 3, were compared for tic and athetoid groups and for the male and female groups using an

CixNtwlrtim mrtir

V1 v2 V3 v4 s v5 V6 v7

for

TABLE 2 h pammeters and speech proficiency rat rigs.

v2

V3

v4

VI

V6

v7

Rating

-0.77s

a022 -0.035

0.1% -0.336 0.205

-0. lOi 0.116 -0.017 0 155

0,153 -0.200 0.059 0.233 0.423

-0.SS5 0.570 -0.1% 0.039 0.304 -0.118

-0.835 0.826 0.023 -0.167 0,119 -0.23: 0.698

of

V I = number artlcuhtory WMJ; V2 - inteltigibilil y; V3 - mean vocai fbndarwmtal frequea~yt V4 - variation of’ vocal fundamaal frequency; VS ‘= ~,,an vocal wund prew~w level;, V6 = variation of vocal auund pr~aupa Ieve& VI = word-per-minute reading note.

390

W. hf. CLARKEand W. R. HO0PS TABLE 3 Regressionanalysis for predictingspeech pf&hcy

rathqs. F

Variable

Multiole R

Numberof ArticulatoryErrors intell@ibility Mean Vocal FundamentalFrequency Variationof Vocal PundamentaI Requency Mean Vocal Sound I%casumLevel Variationof Vocal !kund Prwssu~ Level Word per Minute Reading Rate

-0.3999 0.3417 0.1047

IS.7w 9.w 2.49

0.011s -0. -0.0627 0.3028

Q.oa 0.1s 0.74 11&P+

df t,42. **p > 0.01.

analysis of various procedure as described by Winer ( 1962). The summari these results are shown in Tables 4- 10. Examination of these results indicated that the spastic group made dgnitiandy less articulatory errors, were more intelligible, and tended to read at a significantly faster rate than did the athetoid group. Comparison of the male and female groups on these parameters indicated that the male sample made a significantly greater number of articulatory errors than did the female subjects. Dkussion The results of the regression analysis indicate that there is a relationship between the number of articulatory errors, intelligibility, word-per-minute reading rate and the rating of speech proficiency. Although it is not possible to make any comparisons of these findings with other research, the finding appears to be logical as these parameters are related to the coordination of the speech musculature. The resuhs suggested that an individual subject tended to receive a lower speech proficiency rating if he had a large number of articulatory en~rs ai~d TABLE 4 Summaryof the means of the speech parametersthe spastic and ethetoid subclasses of the palsied sample, Spastic (N= 30)

Numberof Articulatoryhrs helligibility (‘k) Speech Proficiency Ratings speech-sound Resaure Level (dB) FundomentplFrequency(He) W;wd-per-minutereading mte

Male

Fernala

lO.SO 44.33 4.27 73.62 202.43 77.87

10.78 53.42 S.09 74.61 252.64 88.01

35.78 120.73 2.31 74.18 s2.77 45.46

14.27 40.3s 3.94 74.91 254.4s 62.ao

391

RIL P&SIE:D SPEAKWf

1,

92

I 1 46

forcv

?a 74 , ? ISI, tJ

1s.i38** 8.243*+ 1.424

mea between sexand type of cerebralpalsy

for intelligibilky. has -iz49

1 46

2S10.03 87.32 957.37

F

11.06** 7.02 0.24

TABLE 7 Summaryr#analyaiiaofvarancc for svaluadoqofdiffcrer~~abetween8exand type d cerebralpalsy far apcechProficiency ratings. df A (Spattic/Athauid) AxB WMtincell

1 1 1 46

-MS

F

26.89 16.66 1.78 5.05

5.32 3.29 0.35

I’ABU 8 Summaryof analydr of vuhnce for evaluationof diffhrcncesbetweenwx and type of cerebralpalsy far vocal euund premuw level. SOllrcS A (SpardclAthetoid) B (MaIMtie) AxB Within

cell

df

MS

1 I 1

2.11 8.22 -22 5.03

46

F

0.41 ‘1.632 WI4 ,:-

-

W. M. CLARKEand H. R. H0OPS

392

TABLE 9 Summaryof analysis of variancefor evaluationof diftkenws between sex and tYpeof for vocal fundamentalfkequency. MS

F

1

4934.39

1

10638.94

2.79 6. 2.33

df

SOUrCe

A (Spastic/Athetoid) B (MalaFemale) AxB Within cell

1 46

4123.36 1766. I1

TABLE IO Summaryof analysis of variancefor evaluationof differencesbetween sex and type of c for readingrate. Source

df

A (SpasticlAthetoid) B (Male/Female) AxB Within cell **p

1 1.

1 46

MS 9317.84 1903.69 96.66 1377.35

P 7.29@* I .38 0.07

c 0.01.

a slower reading rate. From a simplistic view of these results it would appear likely that the more neurologically impaired a subject, the less coordination and control of the speech musculature and consequently speech tends to be far more laborious and slow and with more articulatory errxxs. The results pertaining to the spastic and athatoid subclasses should be viewed with some caution in that validation of each subject’s neutogical difficult and in fact it may be impossible to con&dall of thevmiabl with the neurologrcal impairment in the two groups. Evaluation on the overall results of this investigation may be drawn with the Alldings of other researchers mu view of the differences in measurement techniques, Further, the possibility of differences in the degree of involvement in the populationsin this invwti~ation and in those in other studies may be suggested as a possible source of variation. A second point which provides for some speculation is the ratingtechniqueas used in the investigations by Rutherford (1944), LeGthand Steer (1958) 8 Hammill and Irwin ( l%S), and Hammill and Myers ( 1968). The question that must be raised is whether or not an individual can make a rating of one particular parameter of speech without being influenced by one or more of the other speech parameters.

CYm

ML PALSlBD

SPBAKERS

of this study was to determine the relationship

393

that

palsied children: 30 spastic and 20 eve1 of leading. Each subject was passage, responding yed to listenemand measuresof n h proficiency rating were made of selected aspects of the readingpassage vocal sound pressure level and mean vocal fundamental ated. The graphic trace of the vocal sound pressure level

of predictability of speech proficiency ratings for the intelligkility , and word-per-minute

mmute reading rate, and they were less intelligible than the athetoid group. Wnder the limitations of the size and type of subject sample, experimental procedures, and statistical procedures used, the following conclusions are present. of predictability between speech proficiency is a sign~~~ant deg ratings and articulatory ability) intelligibility and reading rate. 2, The spastic subjects tended to be better in articulatory ability, intelligibility

i, EL, and Matthews, J. (I9SS). Predicting intelligibility of cerebral palsied speech.1. Speech Ueurr, Rlr. 1:331-343. Dumll, D. (1935). Burnll A&8& gfReudimg D@kulty, New York: Harcourt, Brace and World. Hammill, 0.. and Irwin, 0. (l%S). Speechdifferences among cerebral palsy subclasses.Except. C’ICIM.3 1:277-280. Hammill D., and Myers, P. (19681).Certain speechand linguistic ability in subclassesof cerebral palsy. Percept. lwotor Skills 2651 l-514.

394

W. M. CLARKE and H. R. HOOPS

W., and Steer. M. (1958). Comparison of judged speech characteristics of athetoids and spastics. Cerebr. Palsy Rev. 19:1$19. Rutherford, B. (1944). A comprehensive &tidy of loudness, pitch, rate, rhythm, and quality of children handicapped by cerebral palsy. /. Speech Hear. Disord. 9~263-271, Templin, M., and Darley, F. (1960). 7’lre Tenqdin Darley Tests 4 Arricrrkrrion. IO-: State University of Iowa. Wine:. & (1962). Statistical Principles in Experimental Design. New York: McGraw-Hill.

L&h,

Wolfe, !V. (!9SlJ). A comprehensiveevaluation of 50 cases of cerebral palsy. 1. Qwct!~ Hew. Disord. 15234-25 1.