Biomedical subjects
A M Robbins
Publications and source records attributed to A M Robbins.
Longitudinal evaluation of communication skills of children with single- or multichannel cochlear implants.
Performance on speech perception, speech production, and language tests was measured over time in children who used the 3M/House or the Nucleus cochlear implant. The speech perception and production results demonstrated higher performance levels and faster rates of learning for the multichannel than for the single-channel users. The performance of the children with the single-channel implant on the speech perception and production measures reached a plateau by 1.5 years post implant, whereas the children using the multichannel device continued to show improvement after 2 or more years of implant use. Changes in language were limited over time with no obvious difference in performance as a function of type of implant.
Effect of age at onset of deafness on children's speech perception abilities with a cochlear implant.
The speech perception abilities of 37 children with cochlear implants (single-channel or multichannel) were examined as a function of age at onset of deafness. There was no significant difference in the speech perception abilities of implanted children who were born deaf and those of implanted children who lost their hearing during the first 3 years of life. In contrast, the performance of children whose age at onset of deafness was 5 years or later was significantly better than that of the children with congenital or early-acquired deafness on tests of stress pattern categorization, closed-set word identification, open-set identification of common phrases, and lipreading enhancement.
Comparison of speech perception abilities in deaf children with hearing aids or cochlear implants.
The speech perception abilities of deaf children with a single- or multi-channel cochlear implant are compared with those of deaf children who derive substantial benefit from conventional hearing aids. The children with hearing aids have unaided pure-tone thresholds ranging from 90- to 110-dB HL through at least 2000 Hz, and aided thresholds of 30- to 60-dB HL. The group data show that the speech perception scores of the subjects with hearing aids were significantly higher than those of the subjects with implants on a range of speech perception measures. Although a few subjects with implants achieved scores as high as those who used hearing aids, the majority did not. Even though the children with implants receive substantial benefit from their devices, they continue to have limited auditory perception abilities relative to their peers who derive benefit from conventional hearing aids. The data highlight the importance of establishing hearing aid benefit in potential candidates for implant.
Speech perception abilities of children with cochlear implants, tactile aids, or hearing aids.
The purpose of this experiment was first, to compare the performance of three matched groups of experimental subjects who used either a single-channel cochlear implant, a multichannel cochlear implant, or a two-channel vibrotactile aid on a battery of speech perception measures, and second, to compare the performance of subjects with residual hearing who used hearing aids to that of the three groups of experimental subjects. The results revealed that the subjects using hearing aids achieved the highest scores on all measures. The performance of the group of multichannel implant users was significantly higher than that of the single-channel implant users on tests involving discrimination of speech features, categorization of stress patterns, closed-set identification of familiar words, and identification of common phrases with and without visual cues. The performance of the subjects using 3M/House and Tactaid II devices was similar on all tests except those requiring integration of auditory or tactile cues and visual cues, on which the 3M/House device users achieved significantly higher scores than did the Tactaid II device users.
Evaluating meaningful auditory integration in profoundly hearing-impaired children.
The Meaningful Auditory Integration Scale (MAIS) was developed to evaluate meaningful use of sound in everyday situations by profoundly hearing-impaired children. Information about the use of sound in everyday situations is obtained with a parent interview technique. Initial findings obtained with this scale are reported in Experiment 1 for children who use a hearing aid, single-channel cochlear implant, multichannel cochlear implant, or two-channel tactile aid. The hearing aid users were perceived by their parents to use sound in everyday situations to a greater extent than were the users of either implant or the tactile aid. There was a trend toward slightly higher performance by the multi- than by the single-channel cochlear implant users. The tactile aid users were perceived by their parents to use sound in a meaningful way to the most limited extent. Scores on the MAIS, which were obtained on a longitudinal basis, are reported in Experiment 2. The findings suggest that meaningful auditory integration continued to develop over time in children who used each type of sensory aid.
Analysis of the spontaneous speech samples of children with cochlear implants or tactile aids.
Analyses were performed on the spontaneous speech samples produced by profoundly hearing-impaired children who used the 3M/House single-channel cochlear implant (n = 7), the Nucleus multichannel cochlear implant (n = 7), or the two-channel tactile aid, the Tactaid II (n = 12). Speech recordings were obtained in the predevice condition, and after 6- and 12-months use. The speech of the children in the three experimental groups was compared to that of a control group of subjects who used a tactile aid inconsistently and received minimal speech training. Several new analysis procedures were developed to describe adequately the characteristics of the children's speech. The results revealed that all three experimental groups and the control group showed an increase in their production of sounds classified as English phonemes in the postdevice conditions. It was apparent at both the 6- and 12-months postdevice intervals that the most dramatic improvements were made by the users of the Nucleus device. The changes made by the Tactaid and 3M/House users were similar. The subjects with the Nucleus device also developed more diverse phonetic repertoires over time than did the other experimental subjects. More subjects with the Nucleus device acquired fricatives, liquids, glides, voiceless consonants, and high front vowels than did the subjects in the other groups. The subjects in the control group developed the most limited phonetic repertoires.
Initial findings with a wearable multichannel vibrotactile aid.
Data are presented on the speech perception performance of two profoundly hearing-impaired subjects while using a two-channel vibrotactile aid (Tactaid II) or a new, seven-channel instrument. Both subjects, one a profoundly hearing-impaired teenager and one a postlingually deaf adult, are experienced users of tactile aids. The data suggest better recognition of speech features, words, environmental sounds, and enhancement of lipreading skills with the new multichannel instrument than with the two-channel device.
DNA polymorphisms of the apolipoprotein B gene in patients with premature coronary artery disease.
Elevated plasma levels of low density cholesterol and their major apolipoprotein (apo B) are associated with an increased risk of coronary artery disease (CAD). We have examined allele frequencies of restriction fragment length polymorphisms (RFLP) of the apo B gene in 111 male Caucasians with premature CAD (mean age 49 +/- 7 years) and in 122 elderly Caucasian males (mean age, 73 +/- 5 years), free of clinical cardiovascular disease. The rare allele (R1) of the EcoR1 RFLP in exon 29, resulting in an amino acid change (Glu----Lys4154) was seen more frequently in CAD than in controls (0.270 vs 0.207, P less than 0.05). The R1 RFLP and the MspI insertion polymorphisms (MI) within the 3' hypervariable region (HVR) were observed together in 87% and are likely in linkage disequilibrium. The MI RFLP were slightly more frequent in CAD than control (0.239 vs. 0.211, P = 0.08). A second MspI RFLP in exon 26 results in an amino acid change (Arg----Glu3611); the rare allele M2 was seen more frequently in patients than in controls (0.150 vs. 0.057, P less than 0.005). No significant differences in allele frequencies were observed for the Xba1 RFLP in exon 26 (0.500 vs. 0.529, P = ns) or for the PvuII RFLP near the 5' end (P2) (0.105 vs. 0.088, P = ns). No statistically significant differences in lipid, lipoprotein cholesterol or apolipoproteins A-I and B were observed in patients or in controls. Two of the RFLPs examined (R1 and M2) result in changes in amino acid sequence and their allele frequencies are increased in CAD cases when compared with controls. Genetic variability within the apo B gene may thus contribute to cardiovascular risk. The physiological effects of individual mutations within apo B remain to be determined. It is unlikely, however that the single site polymorphisms examined in this study, will impart further information about CAD risk than conventional lipid parameters.
Performance of deaf children with cochlear implants and vibrotactile aids.
A longitudinal study is under way to examine the speech perception and production skills of deaf children who use a single- or multi-channel cochlear implant, or a two-channel tactile aid. The speech perception data showed that the majority of subjects who achieved the highest scores on a range of measures used the multi-channel cochlear implant. The production data showed that all three types of sensory aids were effective in promoting production skills, with the cochlear implant users showing the greatest gains in this area.