Biomedical subjects
H Ackermann
Publications and source records attributed to H Ackermann.
Stroboscopic articulography using fast magnetic resonance imaging.
A method to display dynamic aspects of vocal tract configuration during speech production by means of fast magnetic resonance imaging is presented. Data acquisition during repetitive movement relies on a stroboscopy-like procedure. The time resolution achieved is 120 images s-1 in a selected plane. As compared with other techniques of kinematic measurements of speech motor processes, this procedure allows for visualization of the temporal and spatial coordination of all relevant articulators, e.g. the entire tongue, the velum and the lower vocal tract. As an example, the method was applied to repetitions of stop consonant-vowel-nasal syllables.
Speech disorders following severe traumatic brain injury: kinematic analysis of syllable repetitions using electromagnetic articulography.
Using electromagnetic articulography, the lips, the tip of the tongue, and the tongue dorsum were tracked during repetitions of the syllables [pa], [ta] and [ka] in 10 speakers with dysarthria following severe traumatic brain injury and in 10 age-matched control subjects. When asked to produce the syllable trains as fast as possible, the patient group showed a rather homogeneous pattern of movement abnormalities including prolonged syllable durations and reduced peak velocity/amplitude ratios. Most presumably, limited speed generation gives rise to the impaired ability to increase speech rate. During the habitual speaking condition, reduced velocity/amplitude ratios were restricted to the tongue tip and tongue dorsum. Obviously, the tongue and the lips are differentially affected in dysarthria following severe traumatic brain injury.
Dysphonia subsequent to severe traumatic brain injury: comparative perceptual, acoustic and electroglottographic analyses.
We tested the applicability of the Goettinger Hoarseness Diagram (GHD) for quantitative evaluation of voice disorders after severe traumatic brain injury (TBI) and compared the obtained data with those from established voice analysis systems such as the Multi-Dimensional Voice Program (MDVP), electroglottography (EGG) and perceptual ratings using sustained vowel productions from 10 patients with TBI dysarthrophonia at late stages postinjury and of 10 healthy control speakers. Statistical analyses revealed significant intergroup differences with respect to various acoustic and perceptual measures, i.e., irregularity component, noise component, noise-to-harmonic ratio, shimmer, jitter, roughness, creakiness, strained-strangledness, hypernasality. By contrast, the considered EGG estimates, i.e., open quotient and speed quotient, did not allow for separation of patients and controls. In addition, the two GHD components exhibited close correlations to perceived roughness and creakiness, on the one hand, and breathiness and, to some degree, nasality, on the other, whereas the MDVP parameters failed to differentiate between these two perceptual modes of phonation.
Coarticulation in slow speech: durational and spectral analysis.
Durational and spectral measures of anticipatory as well as perseverative coarticulation were obtained from the acoustic speech signal of German sentence utterances produced by six young female speakers at comfortable and at slowed speech rate. The test sentences comprised a systematically varied nonsense word embedded into a carrier phrase. Anticipatory and perseverative coarticulation were characterized by different patterns of durational and spectral features. Inter-speaker variability was considerable, particularly with respect to anticipatory vowel-to-vowel coarticulation. As a rule, slowing of speaking rate resulted in a decrease of perseverative coarticulation in the presence of unchanged anticipatory effects. In conclusion, these data corroborate the suggestion that different mechanisms underlie anticipatory and perseverative coarticulation.
[The health teachings of Maimonides. Medical and religious philosophical aspects].
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[On experiences with the new denture retainers (saddle) for partial dentures].
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