Arch. klin. exp. 0hr.-, Nas.- u. Kehlk.Heilk. 198, 158--166 (1971) © by Springer-Verlag 1971

The Auditory Evoked Potentials of Language Disordered Children G. A. W. SHARRARD University of Manchester, Department of Audiology and Education of the Deaf, University of Manchester

Summary. A pilot survey of Language Disordered Children has been made in two deaf schools in Manchester with a view to beginning a much longer and deeper

study later. Cortical Audiometry has been used in this study and correlated with other tests by audiologists using subjective audiometry and by psychologists with a battery of tests of both general function and language performance. Auditory thresholds, and both amplitudes and latencies of the threshold evoked responses have been determined for this group of approximately 40 children, half of whom are termed "Language Disordered". The concept of Language Disorder is discussed, and the results reported and compared with the results obtained by the other workers. A second battery of tests with tape recorded stimuli has been used also, involving word messages and their reversed equivalents, and incorporating the conception of Contingent Negative Variation. One of the two groups of children has been tested in this way, and the results are discussed. Introduction

This work was undertaken as part of an interdisciplinary "Feasibility Study" to estimate the possibility of a much larger and longer investigation of "Language Disordered" children within certain deaf schools. The "Language Disorder" term was a loose one, implying additional disabilities as well as deafness, resulting in almost all cases in an original failure to progress academically as well as could be expected from the known degree of deafness. I n the two schools studied, the headmaster had been asked to present a suitable group of children in matched pairs. Each pair contained a "normal deaf" and "language disorder" child of approximately the same age and sex. I n one school (R.S.D.) the interpretation of Language Disorder had been such as to include a number of problems, including variations of Intelligence Quotient, defective vision, and (in two individual cases) moderate emotional problems and cerebral spasticity. I n the other school (W.H.) an additional criterion within the term had been that the child was compensating well for an additional handicap. I n these cases, "aphasia" in its different forms was probably therefore not the dominant feature. Evoked Response audiometry was used with a threefold purpose: 1. To test objective hearing threshold over two frequencies (sometimes three) in each car, and compare this with the subjective threshold

Auditory Evoked Potentials of Language Disordered Children

159

o b t a i n e d i n d e p e n d e n t l y , n o t i n g differences in s u b j e c t i v e / o b j e c t i v e correlation between "normal deaf" and "language disordered". 2. To n o t e t h e A m p l i t u d e s a n d L a t e n c i e s of as m a n y A u d i t o r y E v o k e d R e s p o n s e s as i t was possible t o o b t a i n on t h e s e children w i t h i n t h e t e s t i n g t i m e a v a i l a b l e (11/~--2h). A s t a t i s t i c a l (variance analysis) c o m p a r i s o n of t h e v a l u e s for t h e t w o groups was t h e n m a d e . 3. To t e s t o u t ~ n e w m e t h o d of A u d i t o r y s t i m u l a t i o n w i t h t a p e r e c o r d e d v e r b a l messages on b o t h g r o u p s n o t i n g presence or a b s e n c e o f E v o k e d l~esponse, a n d m a k i n g a c o m p a r i s o n of a m p l i t u d e s a n d latendes thus obtained. A c o m p u t e r - a s s i s t e d s t u d y of t h e l i t e r a t u r e on t h i s t y p e of s t u d y u n c o v e r e d 5¢ r e l a t e d p a p e r s w i t h o n l y four m e n t i o n i n g E v o k e d P o t e n t i a l s w i t h i n t h e l a s t 3 - - 4 years. ( K u r o i w a et al., 1968; Corcelle etal., 1968; F a u r i et al., 1968; Liberson, 1966). I t is also k n o w n , b y p e r s o n a l c o m m u n i c a t i o n r a t h e r t h a n p u b l i c a t i o n , t h a t a t least 3 l a b o r a t o r i e s are i n t e r e s t e d in t h e v e r b a l s t i m u l a t i o n of c o m p u t e r a v e r a g e d responses, in S t a n f o r d Calif., Chicago a n d L u n d , Sweden. T h e V i e n n a School u n d e r Dr. B u r i a n has, of course, a w e l l - d o c u m e n t e d a p p r o a c h to this p r o b l e m t h r o u g h C o n t i n g e n t N e g a t i v e V a r i a t i o n Conditioning studies.

Methods 1. Audiometry Apparatus used was as described in earlier papers (Sharrard, 1968, 1969} consisting of Biomae "500" Averaging Computer, Dynograph Type T Electroencepholograph, Amplivox Model 83 Audiometer, Leyton ME 70 sound-excluding Headset, circuit boxes used with the Biomac to produce measured stimuli, and Devices X Recorder for write-out. Electrodes were in previously described positions on the scalp, mastoid and forehead. Procedure was basically begun with an averaged EEG run using no auditory signal, then followed with a typical response, if obtainable, at 90 or 110 db I.S.O. (allowing for the subject's discomfort) at 1,000 Hz in the right ear. Thresholds were obtained for both ears at 1,000 Hz (checked by subjective observation if possible) then at 2,000 Hz and 500 Hz unless time did not allow. In some good subjects it was possible to obtain a threshold response at 4,000 Hz and 250 Hz, though in most cases time was too limited for this. The subjects tested by this means were 19 children from one Manchester School for the Deaf, aged between 7 and 14, of both sexes (10 being Language Disordered) and 22 children from another Manchester School for the Deaf, aged between 8 and 17, of both sexes (11 being Language Disordered).

2. Language Tests Each subject was given the stimulus of two separate series of tapes. The first series was based on a set of instructions for the production of Contingent Negative Variation, made into the form of a 64~ word message with each separated from its fellow by 2see. A "fomwrds" message was followed by a "reversed" message, produced by reading the message backwards and reversing the tape. In this way, the response to meaning could be separated from the response to a sound.

160

G . A . W . Sharrard:

The average sound volume level was usually set at 110 db I.S.O. The tapes were followed by a 64-stimulus pair run to produce Contingent Negative Variation (sound followed 1/2 sec later by light with instructions to press a button to put the light off), which the deaf and language disordered children managed often very well. To test the significance of the order of these stimuli, the orders of "forward", "reversed" and "CNV" sequences were changed about in Latin Square fashion. Conclusions

1. This s t u d y shows t h a t i t is possible t o t e s t b o t h severely d e a f a n d l a n g u a g e d i s o r d e r e d school children w i t h ease, a n d w i t h g o o d correspondence t o i n d e p e n d e n t s u b j e c t i v e m e t h o d s . 2. L a t e n c y a n d A m p l i t u d e m e a s u r e m e n t s on t h e E v o k e d R e s p o n s e s of these children do n o t p r o v i d e a c o n v e n i e n t m e t h o d of distinguishing b e t w e e n deafness with, a n d deafness w i t h o u t , l a n g u a g e disorder. 3. T a p e - r e c o r d e d v e r b a l messages can be u s e d t o p r o v i d e E v o k e d Responses on these children. I n b o t h g r o u p s t h e r e is some differentiation b e t w e e n messages t h a t are m e a n i n g f u l a n d meaningless, b u t t h e overall response p r e s e n t s difficulties in i n t e r p r e t a t i o n . These difficulties m a y be resolved b o t h b y f u r t h e r s t u d y on t h e s a m e lines a n d b y i n c r e a s e d s o p h i s t i c a t i o n of t h e m e t h o d in f u t u r e m o n t h s . The second series o£ t a p e s were of s p o k e n n u m b e r s , one to eight, r e p e a t e d eight t i m e s a t 2 see i n t e r v a l s , a g a i n giving a 64-word message. There were four messages in this series, p r o d u c e d b y s p e a k i n g t h e n u m P2

Fig. 1

,

500msec

,

Fig. 1. This shows a standard response to a 64-word message containing instructions for the performance of Contingent Negative Variation experiments. There is quite an obvious Evoked Response with the usual P1 and P.~ waves Fig.2. This illustrate the "adult" type of response in a 12 year old boy. Note the clear P1 wave, deep N 1 wave and prominent P2. The-hr2 which follows is less deep. The stimulus was a tone of 90 dB, 500 Hz, to the left ear :Fig. 3. This illustrates a response more like a younger child, in the same subject, but to a softer (60 dB) tone. This shows greater depth o£-AT2 relative to the curves P1, N1 and P2

N2

N ,

, ~g.2

500msec

L

,

V N2

Pig.3

A u d i t o r y E v o k e d P o t e n t i a l s of L a n g u a g e D i s o r d e r e d Children

161

bers again in eight groups of random number order, then reversing this and the former number tape in the same way as for the first series of "CNV instruction" tapes. Only one of the Deaf School populations could be tested in this way, owing to the demands of time.

Results 1. Thresholds a) A comparison of thresholds obtained on these subjects by this method and by standard subj ective audiometry showed agreement within 10 db I.S.O. in all cases. b) I n most cases the loss of hearing was the same on both sides. The curve of the audiogram was usually "flat", i.e. the same loss or within 10 db I.S.O. at all intersections tested. The nature of the deafness was in all cases perceptive. The following Table 1 shows the distribution of threshold levels. Table 1

110 100 90 80 70 60 50 40 25 ~'1~

1/2 k

1k

2k

4 2 9 2 2 0

t3 2 17 2 1 5 (1) 1

14 0 11 2 2 2 2 2

19

41

35

15 500 lit

2

u~

,

,o

~

2

~o ' 7o

z, go

,,o

17 15

I000 ,

,o

io

~o

70

so

,Io 14

2000

10

2 Io ll

3'o

2

2

l

~T1

io

2 70

Arch. klin. exp. Ohr.-, Nas.- u. Kchlk.Heilk., Bd. 198

2 90

II0

162

G . A . W . Sharrard:

Evoked response Audiometer H Tone-wi controlunidtthI Timing signal Ac~ gr signal Penrecorder Tone ~ ~,,,.~ L~

• • :~ ••

E.E.G. Amplified amplifier E.E.G.signal

Fig. 4. Diagram of apparatus used in Evoked Response audiometry

Fig.5. The ME70 headphones are shown on a young subject, with the complete normal testing set up

Auditory Evoked Potentials of Language Disordered Children Table 2a "Language Disordered" children at Whitebroo~ School. Average three ]requencies, two ears

0

1

~

J

Amplitude (p-V) 5 j

i

J

]1

~

10

i

I

163

Table 2b "Normal Deaf' children at Whitebroo# School. Average three/requencies, two ears. First positive response above threshold 0

i

J

i

AmpLitude {p.V ) 5 i

I

I

10

i

i

i

t

i

I

] I

I

] I

I I Table 3 a "Language Disordered" children at Residential School /or the Deal. Average three ]requencies, two ears. First positive response above threshold (10 dB) Latency 0

50 l

(m sec }

100 1

150

200 i

]

Table 3b "Normal Deaf' children at Residential School /or the Deal

50

Latency (rn sec) 100 150

200

I

]

I

I I

I I I l

I

B o t h ears are shown t o g e t h e r a t each s t i m u l u s level a n d t h e frequencies a r e shown s e p a r a t e l y . I n some eases, no response a t all was o b t a i n e d , t h u s a c c o u n t i n g for t h e absence o f some cases f r o m t h e t a b l e s (i.e. a t 500 H z a n d 2,000 Hz). ll*

164

G.A.W. Shaxrard: 2. Amplitude and Latencies o/the Groups at Audlometric Threshold

Amplitude is defined as the value in microvolts of the "vertical" distance between the N' trough and P~ peak of the Evoked Response wave-form (or the first negative and second positive peak of the nonspecific slow cortical wave series). Latency is defined as the value in milliseconds of the "horizontal" distance between the commencement of the stimulus and the top of the first negative wave. Variance analysis showed that ~here was no significant increase in latency for the "Language Disordered" above the "normal deaf" children, and no change in Amplitude after allowance for variation between individuals and with different threshold sound intensities (see Tables 2 and 3). 3. Amplitudes and Latencies o/the Responses of the Groups to Tape.recorded Verbal Messages

The first pair of recorded messages ("forwards" and "reversed" instructions) produced a contrast in amplitude and latency for the "Language Disordered" group tested, but not for the "normal deaf" group. The "Language Disordered" group showed greater amplitude and shorter latency responses for the forwards message than for the reversed one. The second pair of messages (forward and reversed words alternated, then randomised), and the number tapes showed no specific contrasts

Tabled. "Language Disordered" children at lqesidential School /or the Deaf. Forward: Shaded, reversed tapes: Unshaded

Table 5. "Normal Deaf" children at Residential School/or the Deaf. Forward: Shaded, reversed tapes: Unshaded

Amplitude{~V)

Ar~plitude (p.V) 20 )

5

10

I m i

Forwardm Reversedr"l

m i

m i

i

m

m

Reversedl-I

m i

m

m

!

m i

i

Auditory Evoked Potentials of Language Disordered Children

165

in e i t h e r " L a n g u a g e D i s o r d e r e d " or " n o r m a l d e a f " groups (see T a b l e s 4 a n d 5). This is to thank Professor Taylor for his help and encouragement in the pre" paration of this work, and also the technical staff, Arthur Kettlety and mike Harding, for their help with the technical aspects; also, the students and others who offered themselves as subjects.

References Beagly, H. A., Knight, d . J . : Methods of objective audiometry. J. Laryng. 80, 1127 (1966). -- -- Changes in auditory evoke4 response with intensity. J. Laryng. 81, 861 (1967). Cody, D. T. R., Biekford, R . G . : Cortical audiometry:--an objective method of evaluating auditory acuity in man. Prec. Mayo Clin. 40, 273 (1965). Cohen, J., Offner, F.: Some clinical applications of the CNV and evoked potentials. Electroeneeph. elin. Neurophysiol. 22, 190 (1967). -- -- Palmer, C. W. : Development of the contingent negative variation in children. Eleetroenceph. elin. Neurophysiol. 23, 77 (1967). Davis, H. : Averaged-Evoked Response EEG audiometry in North America. Acta oto-laryng. (Stockh.) 65, 79 (1968). - - H h ' s h , S. K., Shelnutt, J., Bowers, C. : Further validation of E. R. A. J. Speech Hearing Res. 10, 717 1967). Derbyshire, A. J., Driessen, G.J., Palmer, C. W. : Technical advances in the analysis of single, aecoustically evoked potentials. Electroenceph. olin. Neurophysiol. 22, 476 (1967). Feldmar, R.M., Goldstein, R. : Averaged Evoked Responses to synthetic syntax sentences, J. Speech Hearing Res. 10, 689 (1967). Hillyard S.A., Galambos, R.: Effects of stimulus and response contingencies on a surface negative show potential shift in man. Eleetroenceph. olin. Neurophysiol. 22, 297 (1967). Lamb, L. E., Graham, J. T. : Influence of signal variables on evoked response to sound. J. Speech Hearing Res. 10, 257 (1967). McCallum, W. C., Walter, W. G. : The effects of attention and distraction on the contingent negative variation in normal and neurotic subjects. Electroeneeph. olin. Neurophysiol. 25, 319 (1968). Pollock, K. C. : Eleetroencephalie audiometry by cortical conditioning. J. Speech Hearing Res. 10, 706 (1967). Rapin, I.: The young deaf child. Auditory Evoked Response in normal waking adults. Aeta oto-laryng. (Stockh.) Suppl. 206, 113 (1965). -- Graziani, L . J . : Auditory-Evoked Responses in normal brain damaged and deaf infants. Neurology (NIinneap.) 17, 881 (1967). Sharrard, G. A. W.: Observations on auditory evoked cortical response and electronystagmography. J. Laryng. 82, 623 (1968). -- Averaged Evoked Responses and Audiometric stimulation. E.P.T.A. Prec. J. 16, No. 1 (1968). -- Evoked responses--introductory studies on their relationship to the perception of language. J. Laryng. 83, No. 10 (1969). -- The cortical Evoked Response in Audiometry--introductory studies. International Audiology, Vol. VLLL, No. 2--3, pp. 354--360; The editors: International Audiology, Department of Otorhiaolaryngology, University Hospital, Leiden, The Netherlands, 1969.

166

Discussion

Sharrard, G. A. W. : Technical innovations in the field of Evoked Response Audio. merry. E.P.T.A. Proc. J . 16, No. 4 (1969). Walter, W . G . , Cooper, R., Aldridge, V . J . , McCalhim, W.C., Winter, A. L.: Contingent negative v a r i a t i o n : - - a n electric sign of Sensorimotor association a n d expectancy in the h u m a n brain. N a t u r e (Lond.) 208, (1964). -- -- Crow, H. J., MeCalhim, W. C., Warren, W . J . , Aldridge, V. J., Storm v a n Leeuwen, W., Kamp, A. : Contingent negative variation a n d Evoked Responses recorded b y radio-telemetry in flee-ranging subjects. Eleetroenceph. clin. Neurophysiol. 28, 197 (1967). Dr. G. A. W. Sharrard D e p a r t m e n t of Audiology and Education of the Deaf a t t h e University of Manchester Manchester M13 9PL, Great Britain

Discussion K. BURIAN-Vienna: I have a short comment to the last two papers, based on a new examination we presented in 1968 a t the Audi-Congress in London. We called this examination "Language evoked response audiometry". W e tested the patients with two groups of different test words, one group consisting of senseless a n d one group consisting of meaningful words. B y linking a flash to only one group of testwords, the expection of this flash proofed discrimination between the two test word groups. I n the meantime we have improved this program. We are now using more complex programs (slide) : Z i. different names of plants (upper curve) a n d different names of animals (lower curve). The animal words were combined with a flash, a n d you can see t h a t there is a very distinct elevation of t h e curve before the flash or a n y way a difference between t h e two curves which proves t h e discrimination ability of t h e patient. I n the middle curves we can see a similar experiment with numbers a n d colours, b u t there is no difference between t h e two curves. This was a patient who came b y mistake to this examination. This patient was sent for a normal audiogram a n d was ushered into t h e wrong cabin. A t t h e end of the experiment the technician ask t h e p a t i e n t : " D i d n ' t you u n d e r s t a n d t h e words?" a n d she answered: " I ' m sorry, b u t I d o n ' t u n d e r s t a n d German, I ' m English." So this was the reason why we d i d n ' t find a n y difference! On t h e right side of t h e slide we see t h a t t h e amplitude of t h e expectancy wave is decreasing with decreasing discrimination ability. We are now using more difficult, more complex programs: in t h e middle slide you see in t h e left row different mistakes of the articles, in t h e middle row mistakes in the verbs a n d on the right a n d t h e lower side contracdictory a n d non-contradictory statements, a n d in this way we are testing in a m u c h more complex way. T h a t helps us to investigate t h e cause of a comprehensive disturbance. I also w a n t to show you a slide of a fourtysix year old p a t i e n t who h a d a n operation, a t u m o u r remouval within the left temporal hemisphere; one m o n t h after t h e operation he could n o t discriminate verbal contradictions, as seen on t h e left side. There's no difference between two curves, three m o n t h later he developed a n expectancy wave under identical circumstances a n d conditions, b u t t h e p a t i e n t was unable to learn a n y verbal comprehension! Now I t h i n k t h a t with language evoked response audiometry we have a possibility to increase our insight into t h e different factors causing aphasia in a patient.