The auditory brainstem implant (ABI) restores some hearing sensations to patients deafened by bilateral acoustic tumors. Electrodes are stable for more than 10 years. In most cases nonauditory side effects can be avoided by judicious selection of the stimulating waveform and electrode configuration. Most perceptual measurements demonstrate that the ABI produces psychophysical and speech performance similar to that of single-channel cochlear implants. ABI patients receive suprasegmental information in speech and significant enhancement of speech understanding when the sound from the ABI is combined with lipreading.

Antioxidants have been reported to be effective in reducing acoustic trauma in animal models but have not been studied in humans. In this study, the antioxidant N-acetylcysteine (NAC) was evaluated to determine if it would reduce temporary changes in auditory function as a result of exposure to loud music in humans. Pure-tone thresholds and distortion product otoacoustic emissions (DPOAEs) were collected in 31 normal-hearing participants, using a randomized, double-blind, placebo-controlled design, before and after two hours of live music in a nightclub. Using repeated measures analysis of variance, no statistically significant differences were found between participants who received NAC versus a placebo for any of the outcome measures. Across all subjects, the largest pure-tone threshold shift occurred at 4 kHz. DPOAE measures were characterized by reductions in amplitude and a trend for shorter group delay values. When the 3 and 4 kHz data were examined by imposing specific criteria of greater than 2 dB DPOAE amplitude reductions and 10 dB or greater pure-tone threshold shifts, DPOAE reductions occurred more often at 3 kHz, and pure-tone shifts occurred more often at 4 kHz.

No abstract

No abstract

Design-centered learning environments o er great promise for providing e ective, grounded learning experiences. Learners are given a set of design criteria and a library of components which they use to design artifacts that will satisfy the speci ed criteria. Despite their appeal, design-centered learning environments are plagued with complexities that can overwhelm learners. To address this problem, we h a ve d eveloped a proactive problem-solving focus mechanism that helps learners cope with the complexities inherent in design-centered learning. By exploiting a rich model of the design context, the focus mechanism selects design problems and intervenes with multimedia advice. The mechanism has been implemented in Design-A-Plant, a design-centered learning environment for botanical anatomy and physiology. F ormative e v aluations with middle school students are encouraging.