Biomedical subjects

G M Clark

Publications and source records attributed to G M Clark.

At least 37 records · Page 2Linked to original sources

PubMed2001

The role of radiographic phase-contrast imaging in the development of intracochlear electrode arrays.

OBJECTIVE: This study describes the application of a new radiographic imaging modality, phase-contrast radiography, to in vitro human temporal bone imaging and investigates its use in the development of new electrode arrays for cochlear implants. BACKGROUND: The development of perimodiolar electrode arrays for cochlear implants requires detailed information from postoperative radiologic assessment on the position of the array in relation to the cochlear structures. Current standard radiographic techniques provide only limited details. MATERIALS AND METHODS: Nucleus standard electrode arrays and perimodiolar Contour electrode arrays were implanted into the scala tympani of 11 human temporal bones. Both conventional and phase-contrast radiographs were taken of each temporal bone for comparative purposes. RESULTS: Phase-contrast imaging provides better visualization of anatomic details of the inner ear and of the structure of the intracochlear electrode array, and better definition of electrode location in relation to cochlear walls. CONCLUSION: Phase-contrast radiography offers significant improvement over conventional radiography in images of in vitro human temporal bones. It seems to be a valuable tool in the development of intracochlear electrode arrays and cochlear implant research. However, this new radiographic technique still requires certain computational and physics challenges to be addressed before its clinical use can be established.

Cochlea↗

PubMed2001

Synchronization of the neural response to noisy periodic synaptic input.

The timing information contained in the response of a neuron to noisy periodic synaptic input is analyzed for the leaky integrate-and-fire neural model. We address the question of the relationship between the timing of the synaptic inputs and the output spikes. This requires an analysis of the interspike interval distribution of the output spikes, which is obtained in the gaussian approximation. The conditional output spike density in response to noisy periodic input is evaluated as a function of the initial phase of the inputs. This enables the phase transition matrix to be calculated, which relates the phase at which the output spike is generated to the initial phase of the inputs. The interspike interval histogram and the period histogram for the neural response to ongoing periodic input are then evaluated by using the leading eigenvector of this phase transition matrix. The synchronization index of the output spikes is found to increase sharply as the inputs become synchronized. This enhancement of synchronization is most pronounced for large numbers of inputs and lower frequencies of modulation and also for rates of input near the critical input rate. However, the mutual information between the input phase of the stimulus and the timing of output spikes is found to decrease at low input rates as the number of inputs increases. The results show close agreement with those obtained from numerical simulations for large numbers of inputs.

Action Potentials↗

PubMed2001

Effects of hydroxyurea on extrachromosomal DNA in patients with advanced ovarian carcinomas.

PURPOSE: In vitro low concentrations of hydroxyurea eliminate double-minute chromosomes (dmins) containing amplified drug-resistance genes and oncogenes from cancer cells. This clinical trial investigated whether a noncytotoxic dose of oral hydroxyurea could reduce the number of dmins in cancer cells in patients with advanced ovarian carcinomas. EXPERIMENTAL DESIGN: The high frequency of ascites associated with ovarian cancer facilitated the monitoring of cytogenetic variations with minimal discomfort in patients who required frequent abdominal paracentesis. Sixteen patients with advanced ovarian carcinomas resistant to conventional cisplatin-based and/or paclitaxel chemotherapy and with ascites requiring frequent abdominal paracentesis were entered in this study. A course of treatment consisted of a single oral dose of 80 mg/kg hydroxyurea every 3 days for 6 weeks. Blood and i.p. levels of hydroxyurea were determined. We monitored the variations of dmins in tumor cells taken from serial abdominal paracenteses. RESULTS: The median number of courses administered to the patients was 1 (range, 1--9). In ascites, hydroxyurea concentrations were 610.3 +/- 76.3, 219.8 +/- 85.6, and 86.1 micromol/liter at 4, 24, and 30 h after oral administration, respectively. Eleven (78.6%) of 14 patient specimens contained dmins before therapy. The number of spreads with tumor cells containing dmins were reduced by more than 50% in 5 (45%) of 11 and 3 (60%) of 5 patients at the completion of the first and second course of chemotherapy, respectively. Using tumor cells taken directly from the patients and grown in soft agar, we documented that concentrations of hydroxyurea in ascites were too low to have any cytotoxic effects. No grade 3--4 hydroxyurea-related toxicities nor any objective responses were observed. However, despite the utilization of a low noncytotoxic dose of hydroxyurea, two patients had prolonged stabilization of their disease for 6 and 10 months, respectively, with concomitant decreases in the number of dmins that remained until progression. CONCLUSIONS: This study showed that, in some circumstances, a noncytotoxic dose of hydroxyurea given to patients with ovarian cancer can decrease the number of metaphase spreads containing dmins in cancer cells.

Administration, Oral↗

PubMed2001

DNA and cell cycle analysis as prognostic indicators in breast tumors revisited.

Both DNA ploidy and S-phase ploidy are promising prognostic factors for node-negative breast cancer patients. Based largely on the analysis of one large study, much of the reported problems with these factors have been caused by some unappreciated complexities in categorizing DNA ploidy into low- and high-risk groups and the lack of some necessary adjustments to eliminate unwanted correlations between DNA S-phase and ploidy. When both DNA ploidy and S-phase are compensated properly, they become independent prognostic markers, forming a powerful prognostic model.

Breast Neoplasms↗

PubMed2000

Phase I and pharmacokinetic study of irofulven, a novel mushroom-derived cytotoxin, administered for five consecutive days every four weeks in patients with advanced solid malignancies.

PURPOSE: To evaluate the toxicity and pharmacologic behavior of the novel mushroom-derived cytotoxin irofulven administered as a 5-minute intravenous (IV) infusion daily for 5 days every 4 weeks to patients with advanced solid malignancies. PATIENTS AND METHODS: In this phase I trial, 46 patients were treated with irofulven doses ranging from 1.0 to 17.69 mg/m(2) as a 5-minute IV infusion (two patients received a 1-hour infusion) daily for 5 days every 4 weeks. The modified continual reassessment method was used for dose escalation. Pharmacokinetic studies were performed on days 1 and 5 to characterize the plasma disposition of irofulven. RESULTS: Forty-six patients were treated with 92 courses of irofulven. The dose-limiting toxicities on this schedule were myelosuppression and renal dysfunction. At the 14.15-mg/m(2) dose level, renal dysfunction resembling renal tubular acidosis occurred in four of 10 patients and was ameliorated by prophylactic IV hydration. The 17.69-mg/m(2) dose level was not tolerated because of grade 4 neutropenia and renal toxicity, whereas the 14.15-mg/m(2) dose level was not tolerable with repetitive dosing because of persistent thrombocytopenia. Other common toxicities included mild to moderate nausea, vomiting, facial erythema, and fatigue. One partial response occurred in a patient with advanced, refractory metastatic pancreatic cancer lasting 7 months. Pharmacokinetic studies of irofulven revealed dose-proportional increases in both maximum plasma concentrations and area under the concentration-time curve, while the agent exhibited a rapid elimination half-life of 2 to 10 minutes. CONCLUSION: Given the results of this study, the recommended dose of irofulven is 10.64 mg/m(2) as a 5-minute IV infusion daily for 5 days every 4 weeks. The preliminary antitumor activity documented in a patient with advanced pancreatic cancer and the striking preclinical antitumor effects of irofulven observed on intermittent dosing schedules support further disease-directed evaluations of this agent on the schedule evaluated in this study.

Adult↗

PubMed2000

Occurrence and load of selected herbicides and metabolites in the lower Mississippi River.

Analyses of water samples collected from the Mississippi River at Baton Rouge, Louisiana, during 1991-1997 indicate that hundreds of metric tons of herbicides and herbicide metabolites are being discharged annually to the Gulf of Mexico. Atrazine, metolachlor, and the ethane-sulfonic acid metabolite of alachlor (alachlor ESA) were the most frequently detected herbicides and, in general, were present in the largest concentrations. Almost 80% of the annual herbicide load to the Gulf of Mexico occurred during the growing season from May to August. The concentrations and loads of alachlor in the Mississippi River decreased dramatically after 1993 in response to decreased use in the basin. In contrast, the concentrations and loads of acetochlor increased after 1994, reflecting its role as a replacement for alachlor. The peak annual herbicide load occurred in 1993, when approximately 640 metric tons (t) of atrazine, 320 t of cyanazine, 215 t of metolachlor, 53 t of simazine, and 50 t of alachlor were discharged to the Gulf of Mexico. The annual loads of atrazine and cyanazine were generally 1-2% of the amount annually applied in the Mississippi River drainage basin; the annual loads of acetochlor, alachlor, and metolachlor were generally less than 1%. Despite a reduction in atrazine use, historical data do not indicate a long-term downward trend in the atrazine load to the Gulf of Mexico. Although a relation (r2 = 0.62) exists between the atrazine load and stream discharge during May to August, variations in herbicide use and rainfall patterns within subbasins can have a large effect on herbicide loads in the Mississippi River Basin and probably explain a large part of the annual variation in atrazine load to the Gulf of Mexico.

Acetamides↗

PubMed2000

Tumor characteristics and clinical outcome of elderly women with breast cancer.

BACKGROUND: The number of elderly patients with breast cancer is increasing. Limited age-related information available about this disease prompted this study. PATIENTS AND METHODS: The study population was derived from 50828 and 256287 patients with invasive breast cancer in San Antonio breast cancer databases and the Surveillance, Epidemiology, and End Results (SEER) registry, respectively. Tumor biologic and clinical characteristics, local and systemic therapies, and survival according to the patient's age were analyzed. Survival was also compared with that of age-matched women from the general population. RESULTS: In patients 55 years old or older, there was an association between increasing age at diagnosis and the presence of more favorable biologic characteristics of the tumor, including more tumors that express steroid receptors, lower proliferative rates, diploidy, normal p53, and absence of the expression of epidermal growth factor receptor and c-erbB2. In older patients with lymph node-negative disease and/or small tumors, the observed and expected survivals were almost identical. In the SEER registry, the 8-year survival of lymph node-negative patients relative to the expected survival of age-matched women from the general population was 1.01 (95% confidence interval [CI] = 0.98-1. 04) for patients 70-74 years old, 1.06 (95% CI = 1.01-1.11) for patients 75-79 years old, and 1.09 (95% CI = 0.98-1.20) for patients 80-84 years old. CONCLUSION: In women 55 years old or older, advancing age is associated with more favorable tumor biology, and breast cancer survival in older women is similar to survival in the general population irrespective of disease status. This favorable outcome should be considered when making clinical decisions in older patients.

Aged↗

PubMed2000

Estrogen receptor (ER) and progesterone receptor (PgR), by ligand-binding assay compared with ER, PgR and pS2, by immuno-histochemistry in predicting response to tamoxifen in metastatic breast cancer: a Southwest Oncology Group Study.

Results of estrogen receptor (ER) and progesterone receptor (PgR) ligand-binding assays (LBAs) are strongly correlated with ER and PgR by immuno-histochemistry (IHC). To investigate whether ER and PgR by IHC are also strongly correlated with tamoxifen response, time to treatment failure (TTF) and overall survival (OS), the results of the 2 methods were directly compared in 205 patients with ER(+) metastatic breast cancer treated with daily tamoxifen (Southwest Oncology Group protocol 8228) with 9 years median follow-up. pS2, another estrogen-regulated molecule, was also analyzed. Tumors were scored for IHC from 0 to 5, according to the proportion of positively stained cells. These IHC scores for both ER and PgR were significantly associated with LBA levels (p < 0.001). There was a significant direct relationship between higher IHC ER, PgR and pS2 and increasing response to tamoxifen. TTF and OS were also significantly longer for patients with higher ER or PgR, but not pS2, IHC scores. Low, intermediate and high ER or PgR categories showed similar differences in response rates whether defined by LBA or IHC. In logistic regression models which included ER, PgR and pS2 by IHC; ER and PgR by LBA; and menopausal status, only ER (IHC) and pS2 (IHC) retained significance for predicting tamoxifen response (p = 0. 02 and p = 0.005, respectively), along with menopausal status (for PgR by IHC, p = 0.09). Increasing ER and PgR by IHC, as by LBA, are thus significantly associated with a progressively better response and longer survival in ER(+) metastatic breast cancer. pS2 is also predictive in this setting.

Antineoplastic Agents, Hormonal↗

PubMed2000

Effects of intracochlear factors on spiral ganglion cells and auditory brain stem response after long-term electrical stimulation in deafened kittens.

Using an animal model, we have studied the response of the auditory brain stem to cochlear implantation and the effect of intracochlear factors on this response. Neonatally, pharmacologically deafened cats (100 to more than 180 days old) were implanted with a 4-electrode array in both cochleas. Then, the left cochlea of each cat was electrically stimulated for total periods of up to 1000 hours. After a terminal (14)C-2-deoxyglucose (2DG) experiment, the fraction of the right inferior colliculus with a significant accumulation of 2DG label was calculated. Using 3-dimensional computer-aided reconstruction, we examined the cochleas of these animals for spiral ganglion cell (SGC) survival and intracochlear factors such as electrode positions, degeneration of the organ of Corti, and the degree of fibrosis of the scala tympani. The distribution of each parameter was calculated along the organ of Corti from the basal end. There was a positive correlation between SGC survival and the level of fibrosis in the scala tympani, and a negative correlation between SGC survival and the degree of organ of Corti degeneration. Finally, there was a negative correlation between the 2DG-labeled inferior colliculus volume fraction and the degree of fibrosis, particularly in the 1-mm region nearest the pair of electrodes, and presumably in the basal turn.

Animals↗

PubMed2000

Comparison of electrode position in the human cochlea using various perimodiolar electrode arrays.

OBJECTIVE: This study was conducted to evaluate the insertion properties and intracochlear trajectories of three perimodiolar electrode array designs and to compare these designs with the standard Cochlear/Melbourne array. BACKGROUND: Advantages to be expected of a perimodiolar electrode array include both a reduction in stimulus thresholds and an increase in dynamic range, resulting in a more localized stimulation pattern of the spiral ganglion cells, reduced power consumption, and, therefore, longer speech processor battery life. METHODS: The test arrays were implanted into human temporal bones. Image analysis was performed on a radiograph taken after the insertion. The cochleas were then histologically processed with the electrode array in situ, and the resulting sections were subsequently assessed for position of the electrode array as well as insertion-related intracochlear damage. RESULTS: All perimodiolar electrode arrays were inserted deeper and showed trajectories that were generally closer to the modiolus compared with the standard electrode array. However, although the precurved array designs did not show significant insertion trauma, the method of insertion needed improvement. After insertion of the straight electrode array with positioner, signs of severe insertion trauma in the majority of implanted cochleas were found. CONCLUSIONS: Although it was possible to position the electrode arrays close to the modiolus, none of the three perimodiolar designs investigated fulfilled satisfactorily all three criteria of being easy, safe, and atraumatic to implant.

Cochlear Implantation↗

PubMed2000

Technical factors accounting for stability of a bilateral sagittal split osteotomy advancement: wire osteosynthesis versus rigid fixation.

OBJECTIVE: Relapse after bilateral sagittal split osteotomy has been attributed to various technical factors that are inherent in the surgical procedure. The purpose of this article was to analyze technical factors that predispose to relapse when wire or rigid fixation is used. STUDY DESIGN: Patients were randomized to either rigid or wire osteosynthesis. Cephalometric radiographs were obtained and digitized at multiple time periods before and after surgery. Data were analyzed through use of 2-sample t tests and stepwise regression analyses. RESULTS: Multivariate analysis indicated that the following factors correlated with relapse: initial advancement, change in ramus in inclination, change in the mandibular plane, and fixation type. CONCLUSIONS: Relapse increased with the amount of initial advancement and, to a lesser extent, with control of the proximal segment and change in the mandibular plane. These factors are similar for wire osteosynthesis and rigid fixation.

Adolescent↗

PubMed2000

Bilateral sagittal split osteotomy and temporomandibular disorders: rigid fixation versus wire fixation.

OBJECTIVE: The effects of orthognathic surgery on temporomandibular disorders may be related to the surgical method that is used. Specifically, it has been suggested that the choice of stabilization technique may play a major role in the functional outcome of mandibular advancement surgery. The purpose of this study was to prospectively compare long-term (2 years) signs and symptoms of temporomandibular disorders after orthognathic surgery with bilateral sagittal split osteotomy in 127 patients randomized to receive rigid or wire fixation. STUDY DESIGN: Signs and symptoms of temporomandibular disorders were evaluated before and 2 years after surgery by means of the overall craniomandibular index (CMI), dysfunction index (DI), and muscle index (MI). Patients also reported subjective symptoms of temporomandibular disorders by marking areas of pain on a standard drawing of the head and rating the pain in each area on a scale ranging from 1 (very mild) to 7 (very extreme). Subjective pain was also assessed through use of the Oral Health Status Questionnaire and by a rating of the difficulty in opening the mouth because of pain. RESULTS: There were no statistically significant differences in the CMI, MI, or DI change scores between the wire and rigid fixation groups (mean CMI(wire) = 0.05, mean CMI(rigid) = 0.04; mean DI(wire) = 0.02, mean DI(rigid) = 0. 01; mean MI(wire) = 0.08, mean MI(rigid) = 0.08) 2 years after surgery. Temporomandibular joint sounds also demonstrated no significant differences between the two fixation methods. Subjective pain reports were consistent with the clinical examinations. On average, both wire and rigid scores decreased slightly, but the change scores were not significantly different between groups. CONCLUSIONS: These findings suggest that the long-term (2 years) effects of wire and rigid internal fixation methods on the signs and symptoms of temporomandibular disorders do not differ. Earlier concerns about increased risk for temporomandibular disorders with rigid fixation were not supported by these results.

Adult↗

PubMed2000

Neurosensory differences after wire and rigid fixation in patients with mandibular advancement.

PURPOSE: The purpose of this analysis was to compare the frequency and severity of nerve damage with rigid and wire fixation in patients participating in a prospective, randomized clinical trial. PATIENTS AND METHODS: One hundred twenty-six patients who required a bilateral sagittal split osteotomy and mandibular advancement were randomly assigned to receive either rigid or wire fixation. Tactile sensation in the mental nerve region bilaterally was determined presurgically and throughout the subsequent 2 years by using monofilament detection and brush stroke direction. Neurosensory levels were compared between the types of fixation over time. RESULTS: Evaluation with monofilament detection showed no significant difference between types of fixation throughout the 2-year follow-up. However, brush stroke determination showed significantly greater hypesthesia with rigid compared with wire fixation from 8 weeks through 2 years postoperatively. CONCLUSION: Rigid fixation resulted in more anesthesia in the mental nerve distribution than wire fixation when tested with brush stroke direction. However, increased anesthesia was not present when measured with monofilament determination.

Adolescent↗

PubMed2000

Electrode discrimination by early-deafened subjects using the cochlear limited multiple-electrode cochlear implant.

OBJECTIVE: The aims of this study were to determine whether electrode discrimination by early-deafened subjects using the Cochlear Limited prosthesis varied at different locations on the electrode array, was influenced by the effects of auditory deprivation and experience with electric stimulation, and was related to speech perception. DESIGN: Difference limens for electrode discrimination were measured in 16 early-deafened subjects at three positions on the array: electrodes 18 (apical), 14 (mid), and 8 (basal). Electrodes were stimulated using random variations in current level to minimize the influence of loudness cues. Assessed were correlations between the difference limens, subject variables related to auditory deprivation (age at onset of deafness, duration of deafness, and age at implantation) and auditory experience (duration of implant use and the total time period of auditory experience), and speech perception scores from two closed-set and two open-set tests. RESULTS: The average difference limens across the three positions were less than two electrodes for 75% of subjects, with average limens between 2 and 6.5 electrodes for the remaining 25% of subjects. Significant differences across the three positions were found for 69% of subjects. The average limens and those at the basal position positively correlated with variables related to auditory deprivation, with larger limens for subjects implanted at a later age and with a longer duration of deafness. The average limens and those at the apical position negatively correlated with closed-set speech perception scores, with lower scores for subjects with larger limens, but not with open-set scores. Speech scores also negatively correlated with variables related to auditory deprivation. CONCLUSIONS: These findings showed that early-deafened subjects were generally successful in electrode discrimination although performance varied across the array for over half the subjects. Discrimination performance was influenced by the effects of auditory deprivation, and both electrode discrimination and variables related to auditory deprivation influenced closed-set speech perception.

Age Factors↗

PubMed2000

Electrode discrimination and speech perception in young children using cochlear implants.

OBJECTIVE: The aim was to determine the efficacy of a child-appropriate procedure to assess electrode discrimination ability in young children using cochlear implants and to investigate the relationship of electrode discrimination ability and speech perception performance in children implanted at a young age. DESIGN: An adaptation of the play audiometry procedure was used to assess electrode discrimination in seventeen 4- to 10-yr-old children. The children were required to respond with a game-like motor response when a repeating stimulation on a reference electrode "changed" to a different electrode. They were also assessed on a speech feature discrimination test, a closed-set word recognition test and a nonverbal intelligence task. RESULTS: Sixty-five percent of subjects demonstrated ability to discriminate adjacent electrodes in mid and apical regions of the cochlea, whilst the remaining subjects needed electrode separations of between two and nine electrodes for successful discrimination. In a forward stepwise regression analysis electrode discrimination ability was found to be the strongest factor in accounting for variance in the speech perception scores. Subject variables such as duration of deafness, nonverbal intelligence and implant experience did not significantly account for further variance in the speech perception scores for this group of children. CONCLUSIONS: Electrode discrimination ability was the strongest factor in predicting performance on speech perception measures in a group of children using cochlear implants.

Child↗

PubMed2000

Speech perception as a function of electrical stimulation rate: using the Nucleus 24 cochlear implant system.

OBJECTIVE: To investigate the effect of varying electrical stimulation rate on speech comprehension by cochlear implant users, while keeping the number of stimulated channels constant. DESIGN: Three average rates of electrical stimulation, 250, 807, and 1615 pulses per second per channel (pps/ch), were compared using a speech processing strategy that employed an electrode selection technique similar to that used in the Spectral Maxima Sound Processor strategy (McDermott, McKay, & Vandali, 1992; McDermott & Vandali, Reference Note 1; McKay, McDermott, Vandali, & Clark, 1991) and the Spectral Peak strategy (Skinner et al., 1994; Whitford et al., 1995). Speech perception tests with five users of the Nucleus 24 cochlear implant system were conducted over a 21-wk period. Subjects were given take-home experience with each rate condition. A repeated ABC evaluation protocol with alternating order was employed so as to account for learning effects and to minimize order effects. Perception of open-set monosyllabic words in quiet and open-set sentences at signal to noise ratios ranging from +20 to 0 dB, depending on the subject's ability, were tested. A comparative performance questionnaire was also administered. RESULTS: No statistical differences in group performance between the 250 and 807 pps/ch rates were observed in any of the speech perception tests. However, significantly poorer group performance was observed for the 1615 pps/ch rate for some tests due predominantly to the results of one subject. Analysis of individual scores showed considerable variation across subjects. For some subjects, one or more of the three rate conditions evaluated provided benefits on some speech perception tasks. The results of the comparative performance questionnaire indicated a preference for the 250 and 807 pps/ch rates over the 1615 pps/ch rate for most listening situations. CONCLUSIONS: For the speech processing strategy, implant system, and subjects evaluated in this study, the group results indicated that the use of electrical stimulation rates higher than 250 pps/ch (up to 1615 pps/ch) generally provided no significant improvement to speech comprehension. However, individual results indicated that perceptual benefits could be obtained by adjusting rate of stimulation optimally to suit each subject. Results from one subject, together with tinnitus problems arising from high-rate stimulation for another subject, indicated that high rates of stimulation may in fact be undesirable for some subjects.

Adult↗

PubMed2000

The relationship between speech perception and electrode discrimination in cochlear implantees.

Speech Intelligibility Index (SII) procedures were used to measure the amount of speech information perceived in five frequency bands (170-570, 570-1170, 1170-1768, 1768-2680, and 2680-5744 Hz) by 15 users of the Cochlear Ltd. CI-22M implant and Spectra-22/SPEAK processor. The speech information perceived was compared to that perceived by normal-hearing listeners. The ability of these subjects to discriminate between stimulation on adjacent electrodes corresponding to each frequency band was also investigated, using a 4IFC procedure with random current level variations of between 0% and 60% of the dynamic range. Relative to normal-hearing listeners, speech information was, on average, significantly more reduced in the four frequency regions between 170 and 2680 Hz than in the region 2680-5744 Hz. There was a significant correlation between electrode discrimination ability (when the random level variation encompassed 20% or more of the dynamic range) and the amount of speech information perceived in the four frequency regions between 170 and 2680 Hz. There was no such correlation in the region 2680-5744 Hz, regardless of the extent of random level variation. These results indicate that speech information in the low to medium frequencies is more difficult for implantees to perceive, that this difficulty is correlated with the difficulty in discriminating electrode place in the presence of random loudness variations, and that fine spectral discrimination may be relatively more important in the vowel-formant regions than in higher frequency regions.

Adolescent↗

PubMed2000

Generalization of tactile perceptual skills to new context following tactile-alone word recognition training with the Tickle Talker.

The Tickle Talker is an electrotactile speech perception device. Subjects were evaluated using the device in various tactile-alone and tactile-visual contexts to assess the generalization to other contexts of tactile-alone perceptual skills. The subjects were from a group of six normally hearing subjects who had previously received 12 to 33 h of tactile-alone word recognition training and had learned an average vocabulary of 50 words [Galvin et al., J. Acoust. Soc. Am. 106, 1084-1089 (1999)]. The tactile-alone evaluation contexts were sentences, unfamiliar talkers, and untrained words. The tactile-visual evaluation contexts were closed-set words, open-set words, and open-set sentences. Tactile-alone perceptual skills were generalized to unfamiliar speakers, sentences, and untrained words, though scores indicated that generalization was not complete. In contrast, the generalization of skills to tactile-visual contexts was minimal or absent. The potential value of tactile-alone training for hearing-impaired users of the Tickle Talker is discussed.

Adult↗