Electropalatographic, acoustic, and perceptual data on adaptation to a palatal perturbation

Abstract

Exploring the compensatory responses of the speech production system to perturbation has provided valuable insights into speech motor control. The present experiment was conducted to examine compensation for one such perturbation-a palatal perturbation in the production of the fricative /s/. Subjects wore a specially designed electropalatographic ͑EPG͒ appliance with a buildup of acrylic over the alveolar ridge as well as a normal EPG palate. In this way, compensatory tongue positioning could be assessed during a period of target specific and intense practice and compared to nonperturbed conditions. Electropalatographic, acoustic, and perceptual analyses of productions of /asa/ elicited from nine speakers over the course of a one-hour practice period were conducted. Acoustic and perceptual results confirmed earlier findings, which showed improvement in production with a thick artificial palate in place over the practice period; the EPG data showed overall increased maximum contact as well as increased medial and posterior contact for speakers with the thick palate in place, but little change over time. Negative aftereffects were observed in the productions with the thin palate, indicating recalibration of sensorimotor processes in the face of the oral-articulatory perturbation. Findings are discussed with regard to the nature of adaptive articulatory skills.

Comparative Morphology of the Hominin and African Ape Hyoid Bone, a Possible Marker of the Evolution of Speech

“…The AcsCoG might be slightly more sensitive to sensorimotor adaptation as the /s-S/ contrast appeared to increase gradually with introduction of the normal palate and essentially reached baseline values by the last block with the palate. This result resembles a previous study comparing distorted and normal palates in normal speakers (Aasland et al, 2006). There was also an initial perturbation effect that reduced AcsCoG and ArtCoG of /s/ for both palates followed by considerable recovery of the contrast over the course of the study even though full compensation was not attained.…”

“…The presence of complete occlusion was also detected by finding instances of complete horizontal contact across one or two contiguous rows of the electropalate (Cho and Keating, 2009). Acoustic CoG (AcsCoG) was also measured in the annotated region, following the methods reported by Aasland et al (2006): the audio was downsampled to 18 kHz and a 20-ms hamming window was situated at the temporal midpoint of each fricative.The 512-pt FFT of the hamming-transformed acoustic material was then used to calculate the AcsCoG value. A higher value is associated with /s/, which has a shorter anterior resonant cavity, and a lower value is associated with /S/.…”

“…The maximum articulatory center of gravity (ArtCoG) in this region was calculated using the method described in and used by Aasland et al (2006), among others. A higher value generally indicates a more anterior place of articulation.…”

Articulatory and acoustic adaptation to palatal perturbation

“…Of particular relevance to the present investigation is our own work in this area which has focused on, among other things, examining speakers' ability to compensate for structural perturbations of the vocal tract induced by the presence of an artificial palate with a thickerthan-normal alveolar region (e.g., McFarland, 1997, 2000;Aasland et al, 2006). In response to this structural modification, speakers have little difficulty in achieving acoustically and perceptually normal vowel targets.…”

A produção da fala nas diferentes modalidades de reabilitação oral

“…A análise espectral também tem sido utilizada para avaliar os efeitos das próteses dentárias sobre a produção dos sons da fala (CHIERICI; PARKER; HEMPHILL, 1978;GHI;McGIVNEY, 1979;PETROVIC, 1985;ICHIKAWA;KOMODA;HORIUCHI;MATSUMOTO, 1995;McFARLAND, 1997;POMILIO;EL-GUINNDY, 1998;McFARLAND, 2000;RUNTE et al, 2001;JINDRA;EBER;PEŠÁK, 2002;AASLAND;McFARLAND, 2006). Para que os fenômenos acústico e motor da fala aconteçam sem alterações, integridade e harmonia das estruturas participantes da produção de fala são de fundamental importância.…”