gms | German Medical Science

20. Wissenschaftliche Jahrestagung der DGPP Deutsche Gesellschaft für Phoniatrie und Pädaudiologie

Deutsche Gesellschaft für Phoniatrie und Pädaudiologie e. V.

12. bis 14.09.2003, Rostock

Laterality in the Dichotic Listening Test by Feldmann

Poster

  • corresponding author Annette Limberger - Universitäts-HNO-Klinik Tübingen, Abteilung Phoniatrie und Pädaudiologie, Elfriede-Aulhorn-Straße 5, D-72076 Tübingen, Tel. 07071-2988070, Fax. 07071-294412
  • author Harry de Maddalena - Universitäts-HNO-Klinik Tübingen, Abteilung Phoniatrie und Pädaudiologie, Elfriede-Aulhorn-Straße 5, D-72076 Tübingen, Tel. 07071-2988070, Fax. 07071-294412
  • author Ilse Maria Zalaman - Universitäts-HNO-Klinik Tübingen, Elfriede-Aulhorn-Straße 5, D-72076 Tübingen, Tel. 07071-2988070, Fax. 07071-293311
  • author Sibylle Brosch - Universitäts-HNO-Klinik Tübingen, Abteilung Phoniatrie und Pädaudiologie, Elfriede-Aulhorn-Straße 5, D-72076 Tübingen, Tel. 07071-2988070, Fax. 07071-294412

Deutsche Gesellschaft für Phoniatrie und Pädaudiologie. 20. Wissenschaftliche Jahrestagung der DGPP. Rostock, 12.-14.09.2003. Düsseldorf, Köln: German Medical Science; 2003. DocP21

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Veröffentlicht: 12. September 2003

© 2003 Limberger et al.
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Abstract

Previous studies demonstrated that grammar school children with developmental reading and spelling disorders (DD) attained significantly lower scores in the dichotic discrimination test by Feldmann (dDF) than age-matched inconspicuous children. Lower scores of dyslectic children were linked to poor left ear dichotic listening performance. Appropriate measures for laterality are laterality indices (left/right ear preferences). At present no studies exist that demonstrate that lateral indices are useful for interpreting dDF perform-ances. One hundred and fifteen right-handed normal hearing children aged 8 to 10 years (I.Q >84) took the dichotic listening test by Feldmann. Sixty-one Children (DD group) had reading and spelling disorders (ICD 10; F 81.0), whereas the other 54 were inconspicuous (control group). We used the HUGDAHL formula to calculate the laterality indices. Results demonstrated a significant group difference (p<0.009): 48 DD children (78.7%) showed right ear preferences. Twenty nine children (53.7%) in the control group demonstrated right ear preferences. Twenty two DD children (36.1%) presented with an extremely high right ear preference. Calculations of the two factorial analysis of variance (age/group) showed a significant main effect for the factor group. Control group measures also indicated that laterality indices tend to level with age (tendentially), whereas no age effect was registered in the DD group. We believe that the HUGDAHL laterality index can be quite helpful in the interpretation of dDF performance.


Text

Introduction

Previous studies demonstrated that grammar school children with developmental reading and spelling disorders (DD) attained significantly lower scores in the dichotic discrimination test by Feldmann (dDF) than age-matched inconspicuous children [1]. Lower scores of dyslectic children were linked to poor left ear dichotic listening performance. Appropriate measures for laterality are laterality indices (left/right ear preferences). At present no studies exist which demonstrate that laterality indices are useful for interpreting dDF performances.

Method

This study comprised 115 right-handed children with an age range of 8 to 10 years. Each child underwent audiological testing (audiogram and tympanogram) in order to rule out peripheral hearing impairment. Further criteria for participation were obtaining an I.Q. of 84 or more with a nonverbal intelligence test such as the CPM [2] or the S.O.N.-R 5-17 [3]. The children had to attend grammar school (grades 2 - 4). We divided the children into 2 groups: The first group (developmental dyslexia = DD-Group) consisted of 61 children with severe reading and writing problems. The DD-diagnosis was based on the ICD 10 F 81.0 criteria [4]. The second group (control group) comprised 54 children without reading and spelling disorders. The mean age of the DD-Group was 112.8 months and 110.4 months for the control group. The age difference was not significant (p (t) >0.17).

All children had to complete the dDF [5], [6]. In this test subjects listen to different German compound words presented simultaneously over headphones - one to the left ear (e.g. Weizenmehl) and one to the right ear (e.g. Backenzahn). The task is to report both words (non-forced, free recall condition). A laterality index (LI) is calculated according to the formula [(REar-LEar)/(REar+LEar)]*100 [7]. A positive index indicates a "Right Ear Advantage" (REA), while a negative index indicates a "Left Ear Advantage" (LEA). One typical finding of many dichotic tests in normal, right-handed, subjects is the so-called right ear advantage (REA), which means that more items are correctly reported from the right compared to the left ear.

Results

Figure 1 [Fig. 1] presents the relative frequencies of the laterality indices. The laterality indices are presented in intervals of five (see x-axis). It becomes obvious when looking at the frequency distribution that the distribution is quite broad and that both groups demonstrated REAs as well as LEAs. Moreover, the sampling fraction of REA is significantly higher in the DD group than in the control group. Noticeable is the fact that every 4th child (22.9%) in the DD group demonstrated a strong REA (LI > 20) in comparison to the children in the control group (11.2%). The mean differences between the two groups were highly significant (LI-mean control group = 2.98, LI mean DD group = 11.3; T=-3.55; p <0,0006).

Figure 1[Fig. 1]: Distribution of laterality indices of the DD-Group (n=61) and C-Group (n=54).

Table 1 [Fig. 2] shows that eight year old children in the control group still exhibited REAs whereas we were unable to find any in the older children (9 years or older). It was, however quite noticeable that the variance for the 10 year olds in this group decreased significantly. No age effects could be ascertained in the DD group, but each age group demonstrated significant REAs. We measured a highly significant main effect for the factor "group" with a 2x3 factorial analysis of variance (group and age)(F=2.93; p< 0.0162).

Discussion

We consider the dDF to be a reliable instrument for measuring central speech processing in school children eight years of age or older [8]. The assessment and interpretation of this instrument is based mostly on the percentage of the dichotically correct identified word pairs. In this study we observed that laterality indices - in addition to dDF results - are suitable for answering questions concerning differential validity. For example we were able to show that our dyslectic children demonstrated REAs in all three age groups. However, we were unable to identify hearing laterality in the control group for all children who were older than nine.

It seems that the dDF results do not produce reliable information about speech laterality since normally hearing subjects do not demonstrate a specific hearing preference once they have reached a certain age in comparison to other dichotic listening tests such as the dichotic listening test with CV-syllables [7].

Consequently, it is very important to identify auditive, verbal, and cognitive processes involved in the dDF processing. Moreover, when interpreting the results of dichotic listening tests it is paramount to consider methodological procedures. Dichotic listening tests such as the dDF, which uses non-directional double answer procedures, put specific demands on short-term memory, by requiring that the subject keeps one word in short-memory while producing the other word. The dichotic listening method also taps several other neuronal cognitive functions besides the "classic" laterality function such as attention, arousal, and higher cognitive processes. Additional research with the dDF is necessary in order to identify the specific "factors of influence" systematically in order to improve the validity of the dDF.


References

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