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Biomedical subjects

J A Decker

Publications and source records attributed to J A Decker.

5 recordsLinked to original sources
PubMed2004

Optimizing dynamic range in children using the nucleus cochlear implant.

OBJECTIVE: The aim of this study was to investigate the benefits of the preprocessing scheme "Adaptive Dynamic Range Optimization" (ADRO) in children using Nucleus cochlear implants. Previous research with adults indicates improved speech perception in quiet and improved sound quality in everyday listening environments with the ADRO scheme. DESIGN: Children were given 4 wk of take-home experience with ADRO, with a minimum of 2 wk in which ADRO was "locked-in." After 1 wk of ADRO use and again after 4 wk of ADRO use, Bench-Kowal-Bamford (BKB) sentence perception in quiet at a low input level of 50 dB SPL (unweighted root mean square) and sentence perception in noise were compared with the child's everyday (Standard) program and the ADRO program. Children also rated the loudness of a variety of environmental sounds and indicated which program provided the best hearing in a variety of everyday listening situations. RESULTS: On average, BKB sentence perception in quiet at 50 dB SPL was significantly better with the ADRO program compared with the Standard program. The group mean improvement was 8.60%. Similarly, group mean scores for BKB sentences presented at 65 dB SPL in multitalker babble were significantly higher with the ADRO program (an improvement of 6.87%). The ADRO program was the preferred program in 46% of the listening situations, whereas the Standard program was preferred in 26% of situations. Everyday sounds were not unacceptably loud with ADRO. CONCLUSIONS: There was an ADRO benefit for this group of children in quiet and in noise. These findings suggest that young children would benefit from the ADRO programming option being locked in along with other processor settings in the SPrint processor once their MAP levels have stabilized. Some older children and teenagers may choose to use ADRO selectively for specific listening situations.

Acoustic Stimulation↗
PubMed2002

Conversion from the SPEAK to the ACE strategy in children using the nucleus 24 cochlear implant system: speech perception and speech production outcomes.

OBJECTIVE: The main objective of this study was to assess whether speech perception and speech production in children using the Nucleus 24 cochlear implant system improved with a change in speech processing strategy from the SPEAK to the Advanced Combination Encoder (ACE) strategy. The major difference between the two strategies is that ACE uses a higher stimulation rate (in this study the stimulation rate was 900 Hz per channel) compared with the SPEAK strategy, where the stimulation rate is 250 Hz per channel. Information also was obtained regarding the adjustment period after conversion to the ACE strategy. DESIGN: An ABA experimental design was used where scores were initially obtained using the SPEAK strategy' (in the initial A time interval), and subsequently performance was assessed using the ACE strategy (B time interval) and then again with the SPEAK strategy (second A time interval). The duration of the B interval was 10 wk, and the duration for the second A interval was 4 wk. Seven children aged between 9 and 16 yr who had at least 6 mo experience with the SPEAK strategy participated. Open-set monosyllabic CNC word perception in quiet and Speech Intelligibility Test sentence perception in noise was evaluated at the end of each of the time intervals. Word perception was also monitored at fortnightly intervals during the B time interval. Speech production was assessed at the end of the initial A time interval and at the end of the B time interval. RESULTS: Mean word and phoneme scores for open-set words in quiet for the group of seven children were significantly higher with the ACE strategy as compared with the SPEAK strategy scores obtained in both of the A time intervals. For sentences in noise, mean scores using the ACE strategy as well as the SPEAK strategy at the second A evaluation point were significantly higher than the scores using the SPEAK strategy measured at the first A time interval. This suggests that learning effects may have influenced outcomes. For some subjects, an initial decrease in scores was found during the initial 2-wk period after fitting the ACE strategy; however, scores subsequently were found to be similar to or higher than those when using the initial SPEAK strategy. Analysis of speech production assessments showed an improvement in the medial consonant scores after using the ACE strategy. CONCLUSIONS: This study demonstrated that some children were able to benefit from the additional information provided by the ACE strategy as compared with the SPEAK strategy. However, the differences in overall performance between the two strategies appear to be relatively small.

Acoustic Stimulation↗
PubMed1997

Occupational risk of Mycobacterium tuberculosis infection in hospital workers.

We conducted a 4-year (1/89-12/92) retrospective cohort study among employees at a large metropolitan hospital where a nosocomial outbreak of multidrug-resistant tuberculosis (TB) had occurred. We compared the risk of tuberculin skin test (TST) conversion among employees who worked on wards where patients with culture-confirmed TB were cared for ("exposed") with the risk among employees who worked on wards with no such patients ("unexposed"). Exposed employees had a higher 4-year risk of TST conversion (14.5%) than unexposed employees (1.4%) (adjusted relative risk 13.4; 95 percent confidence interval 5.1-35.2). Exposed employees had significantly higher risks of conversion than unexposed employees during 1989-91, but not for 1992. Among the exposed, ward clerks had a risk of conversion (15.6%) only slightly lower than nurses (18.2%). We conclude that employees who worked in areas where patients with active M. tuberculosis infection were cared for, including workers who did not provide direct patient care, had a higher risk of TST conversion than employees who did not work in these areas. Reasons for the decline in risk over time include outbreak termination, fewer admissions of patients with TB, implementation of effective infection control measures, and possible resistance to infection in some members of the study population.

Adult↗
PubMedDate not supplied

Exposures to lead-based paint dust in an inner-city high school.

In response to concerns about lead-based paint (LBP) in an 85-year old high school, an evaluation was conducted to determine whether a lead exposure hazard existed for adult school staff. Deteriorating LBP was present on walls and ceilings throughout the school. At the time of the evaluation, abatement of LBP had been completed in approximately one-third of the school. One-hundred eighteen wipe samples for lead dust were collected from floors, teachers' desks, and interior window sills. Areas selected for sampling were based on the work location of the 45 participants providing blood for lead analysis. Wipe samples from hands were collected from all participants. The geometric means (GMs) for lead dust loadings on sills in unabated rooms (n = 23) and abated rooms (n = 16) were 342 and 102 micrograms/ft2, respectively. Nine sills in unabated rooms and one sill in an abated room exceeded the Housing and Urban Development (HUD) guidelines (500 micrograms/ft2 lead) for residential housing following abatement activity. GMs for lead loadings on floors in unabated rooms (n = 26) and abated rooms (n = 14) were 136 and 70 micrograms/ft2 lead, respectively. Seventeen floor samples from unabated rooms and 3 samples from abated rooms exceeded HUD guidelines (100 micrograms/ft2 lead). The GM blood lead level (BLL) was 2.2 micrograms/dL (range: 0.6-5.6 micrograms/dL), similar to that of the general U.S. population. Despite peeling LBP and significant lead dust loadings, a hazard from LBP was not found for staff at the school. There were no relationships between surface lead and hand lead, BLL and abatement status of assigned work area, or BLL and hand lead.

Adult↗