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Title:
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Akustische, artikulatorische und perzeptive Parameter in der Konsonantenproduktion nach Zungenteilresektion
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Author:
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Katalin Mády
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Email:
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Degree Awarded:
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Ludwig-Maximilians-Universität München
, Department of Phonetics and Speech Communication
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Degree Date:
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2004
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Linguistic Subfield(s):
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Phonetics
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Director(s):
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Hans-Henning Horch
Hans Tillmann
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Abstract:
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In the thesis, acquired organic speech disorders due to oral cavity tumours are investigated under acoustic, articulatory and perceptual aspects.
Parts of the investigation are new in this field and have an explorative character, thus it was chosen to keep the number of subjects and the amount of analysed consonants relatively small (8 males, 4 sounds) and the analysis as detailed as possible.
Articulatory recordings were done by dynamic MRI in the midsagittal plane (8 images/sec), and the analysis was based on the distance between tongue and palate. The acoustic analysis relied on separate recordings and included parameters which are relevant for the segment characterisation: duration, relative intensity, and spectral analysis. The study also involved an auditory evaluation, an acoustic investigation and a measurement of the overall speech ability by an intelligibility and by a perception test.
The investigation of the postoperative realisations of the sibilants /s/ and /S/ led to a somewhat surprising result. It is generally thought that /S/ requires a greater articulatory effort than /s/, what results in a later acquisition during first language acquisition and in a less universal character among different languages. However, both the acoustic and articulatory analysis revealed, that impaired sibilant production almost always lead to a neutralisation, where the acoustic and articulatory parameters of /s/ and /S/ overlapped widely and showed the characteristics of /S/. It seems that the crucial distinctive factor for /s/ and /S/ is rather the tongue shape than the point of articulation. These findings make it necessary to re-examine former hypotheses on the differentiation between alveolar and postalveolar sibilants that are based on a sublingual cavity (Perkell, Boyce and Stevens, 1979) or on a secondary obstacle (Shadle, 1990).
The most severe production difficulties were connected to the alveolar lateral /l/. The apical production, that is characteristic for German, could be achieved only by one of 8 subjects. This could be explained by the fact that the mobility of the tongue tip was restricted in all other subjects. Another explanation would be that the function of genioglossus muscle, that plays a role in the lowering of the tongue body, was actually impaired in all but one subject. Theories regarding the relation of F1, F2, and the F2-F3 distance for apical vs. laminal /l/ production cannot be verified on our data, as the effects that lead to a shift in F1 and F2 are often contrary regarding the point of articulation and the tongue body position.
The velar fricative /x/ did not cause a problem to any of the subjects. The normal production of this sound shows a large articulatory variation (velar and uvular) and does not require exact tongue movements. The choice of the velar or uvular allophone seems to vary not only among persons, but also intra-personally (among recording settings following directly after each other): for one subject, the MRI showed a velar preoperative articulation, while the acoustic characteristics referred to an uvular production. It was observed that the number of uvular realisations was somewhat higher postoperatively. This might result from the fact that the uvular sound requires a smaller degree of tongue body elevation than the velar one.
The intelligibility test revealed that the overall perceptual evaluation is not only influenced by the size and localisation of the resection, but also a higher speech rate can lead to lower intelligibility scores.
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