Biomedical subjects

Aaron Parkinson

Publications and source records attributed to Aaron Parkinson.

4 recordsLinked to original sources

PubMed2006

Bilateral cochlear implants in children: localization acuity measured with minimum audible angle.

OBJECTIVE: To evaluate sound localization acuity in a group of children who received bilateral (BI) cochlear implants in sequential procedures and to determine the extent to which BI auditory experience affects sound localization acuity. In addition, to investigate the extent to which a hearing aid in the nonimplanted ear can also provide benefits on this task. DESIGN: Two groups of children participated, 13 with BI cochlear implants (cochlear implant + cochlear implant), ranging in age from 3 to 16 yrs, and six with a hearing aid in the nonimplanted ear (cochlear implant + hearing aid), ages 4 to 14 yrs. Testing was conducted in large sound-treated booths with loudspeakers positioned on a horizontal arc with a radius of 1.5 m. Stimuli were spondaic words recorded with a male voice. Stimulus levels typically averaged 60 dB SPL and were randomly roved between 56 and 64 dB SPL (+/-4 dB rove); in a few instances, levels were held fixed (60 dB SPL). Testing was conducted by using a "listening game" platform via computerized interactive software, and the ability of each child to discriminate sounds presented to the right or left was measured for loudspeakers subtending various angular separations. Minimum audible angle thresholds were measured in the BI (cochlear implant + cochlear implant or cochlear implant + hearing aid) listening mode and under monaural conditions. RESULTS: Approximately 70% (9/13) of children in the cochlear implant + cochlear implant group discriminated left/right for source separations of <or=20 degrees , and, of those, 77% (7/9) performed better when listening bilaterally than with either cochlear implant alone. Several children were also able to perform the task when using a single cochlear implant, under some conditions. Minimum audible angle thresholds were better in the first cochlear implant than the second cochlear implant listening mode for nearly all (8/9) subjects. Repeated testing of a few individual subjects over a 2-yr period suggests that robust improvements in performance occurred with increased auditory experience. Children who wore hearing aids in the nonimplanted ear were at times also able to perform the task. Average group performance was worse than that of the children with BI cochlear implants when both ears were activated (cochlear implant + hearing aid versus cochlear implant + cochlear implant) but not significantly different when listening with a single cochlear implant. CONCLUSIONS: Children with sequential BI cochlear implants represent a unique population of individuals who have undergone variable amounts of auditory deprivation in each ear. Our findings suggest that many but not all of these children perform better on measures of localization acuity with two cochlear implants compared with one and are better at the task than children using the cochlear implant + hearing aid. These results must be interpreted with caution, because benefits on other tasks as well as the long-term benefits of BI cochlear implants are yet to be fully understood. The factors that might contribute to such benefits must be carefully evaluated in large populations of children using a variety of measures.

Adolescent↗

PubMed2006

Simultaneous bilateral cochlear implantation in adults: a multicenter clinical study.

OBJECTIVE: To determine the efficacy of "simultaneous" bilateral cochlear implantation (both implants placed during a single surgical procedure) by comparing bilateral and unilateral implant use in a large number of adult subjects tested at multiple sites. DESIGN: Prospective study of 37 adults with postlinguistic onset of bilateral, severe to profound sensorineural hearing loss. Performance with the bilateral cochlear implants, using the same speech processor type and speech processing strategy, was compared with performance using the left implant alone and the right implant alone. Speech understanding in quiet (CNCs and HINT sentences) and in noise (BKB-SIN Test) were evaluated at several postactivation time intervals, with speech presented at 0 degrees azimuth, and noise at either 0 degrees , 90 degrees right, or 90 degrees left in the horizontal plane. APHAB questionnaire data were collected after each subject underwent a 3-wk "bilateral deprivation" period, during which they wore only the speech processor that produced the best score during unilateral testing, and also after a period of listening again with the bilateral implants. RESULTS: By 6-mo postactivation, a significant advantage for speech understanding in quiet was found in the bilateral listening mode compared with either unilateral listening modes. For speech understanding in noise, the largest and most robust bilateral benefit was when the subject was able to take advantage of the head shadow effect; i.e., results were significantly better for bilateral listening compared with the unilateral condition when the ear opposite to the side of the noise was added to create the bilateral condition. This bilateral benefit was seen on at least one of the two unilateral ear comparisons for nearly all (32/34) subjects. Bilateral benefit was also found for a few subjects in spatial configurations that evaluated binaural redundancy and binaural squelch effects. A subgroup of subjects who had asymmetrical unilateral implant performances were, overall, similar in performance to subjects with symmetrical hearing. The questionnaire data indicated that bilateral users perceive their own performance to be better with bilateral cochlear implants than when using a single device. CONCLUSIONS: Findings with a large patient group are in agreement with previous reports on smaller groups, showing that, overall, bilateral implantation offers the majority of patients advantages when listening in simulated adverse conditions.

Adult↗

PubMed2004

Bilateral cochlear implants in adults and children.

OBJECTIVE: To measure the benefit (ie, sound localization and speech intelligibility in noise) of bilateral cochlear implants (CIs) in adults and in children. DESIGN, SETTING, AND PATIENTS: Seventeen adults and 3 children underwent testing 3 months after activation of bilateral hearing. Adults received their devices in a simultaneous procedure and children in sequential procedures (3-8 years apart). Adults underwent testing of sound localization and speech intelligibility, with a single CI and bilaterally. Children underwent testing of sound localization, right/left discrimination, and speech intelligibility, with the first CI alone and bilaterally. We used computer games to attract the children's attention and engage them in the psychophysical tasks for long periods of time. RESULTS: Preliminary findings suggest that, for adults, bilateral hearing leads to better performance on the localization task, and on the speech task when the noise is near the poorer of the 2 ears. In children, localization and discrimination are slightly better under bilateral conditions, but not remarkably so. On the speech tasks, 1 child did not benefit from bilateral hearing. Two children showed consistent improvement with bilateral hearing when the noise was near the side that underwent implantation first. CONCLUSIONS: Bilateral CIs may offer advantages to some listeners. The tasks described in this study might offer a powerful tool for measuring such advantages, especially in young children. The extent of the advantage, however, is difficult to ascertain after 3 months of bilateral listening experience, and might require a more prolonged period of adjustment and learning. Future work should be aimed at examining these issues.

Adult↗

PubMed2002

Pediatric outcomes with the nucleus 24 contour: North American clinical trial.

The Nucleus 24 Contour is a new cochlear implant that has recently undergone clinical trials in adults and children. The Contour uses the same electronics as the previous-generation Nucleus 24 (CI24M) but incorporates a downsized receiver-stimulator and a perimodiolar electrode array. The indications for use were expanded to include children as young as 12 months of age and children 24 months of age and older with severe to profound hearing loss who had open-set word recognition up to 30%. The Contour was successfully implanted in 256 children. The mean level of postoperative speech perception with the Contour was significantly better than the preoperative baseline with hearing aids on all measures. Children who had open-set speech perception in an audition-only condition before surgery demonstrated higher levels of postoperative performance with the Contour than children with no open-set speech perception before surgery.

Adolescent↗