The effect of technology and testing environment on speech perception using telehealth with cochlear implant recipients.

PURPOSE: In this study, the authors evaluated the effect of remote system and acoustic environment on speech perception via telehealth with cochlear implant recipients. METHOD: Speech perception was measured in quiet and in noise. Systems evaluated were Polycom visual concert (PVC) and a hybrid presentation system (HPS). Each system was evaluated in a sound-treated booth and in a quiet office. RESULTS: For speech in quiet, there was a significant effect of environment, with better performance in the sound-treated booth than in the office; there was no effect of system (PVC or HPS). Speech in noise revealed a significant interaction between environment and system. Subjects' performance was poorer for PVC in the office, whereas performance in the sound-treated booth was not significantly different for the two systems. Results from the current study were compared to results for the same group of subjects from an earlier study; these results suggested that poorer performance at remote sites in the previous study was primarily due to environment, not system. CONCLUSIONS: Speech perception was best when evaluated in a sound-treated booth. HPS was superior for speech in noise in a reverberant environment. Future research should focus on modifications to non-sound-treated environments for telehealth service delivery in rural areas.

Use of telehealth for research and clinical measures in cochlear implant recipients: a validation study.

PURPOSE: The goal of this study was to compare clinical and research-based cochlear implant (CI) measures using telehealth versus traditional methods. METHOD: This prospective study used an ABA design (A = laboratory, B = remote site). All measures were made twice per visit for the purpose of assessing within-session variability. Twenty-nine adult and pediatric CI recipients participated. Measures included electrode impedance, electrically evoked compound action potential thresholds, psychophysical thresholds using an adaptive procedure, map thresholds and upper comfort levels, and speech perception. Subjects completed a questionnaire at the end of the study. RESULTS: Results for all electrode-specific measures revealed no statistically significant differences between traditional and remote conditions. Speech perception was significantly poorer in the remote condition, which was likely due to the lack of a sound booth. In general, subjects indicated that they would take advantage of telehealth options at least some of the time, if such options were available. CONCLUSIONS: Results from this study demonstrate that telehealth is a viable option for research and clinical measures. Additional studies are needed to investigate ways to improve speech perception at remote locations that lack sound booths and to validate the use of telehealth for pediatric services (e.g., play audiometry), sound-field threshold testing, and troubleshooting equipment.

Persistence of climate changes due to a range of greenhouse gases.

Emissions of a broad range of greenhouse gases of varying lifetimes contribute to global climate change. Carbon dioxide displays exceptional persistence that renders its warming nearly irreversible for more than 1,000 y. Here we show that the warming due to non-CO(2) greenhouse gases, although not irreversible, persists notably longer than the anthropogenic changes in the greenhouse gas concentrations themselves. We explore why the persistence of warming depends not just on the decay of a given greenhouse gas concentration but also on climate system behavior, particularly the timescales of heat transfer linked to the ocean. For carbon dioxide and methane, nonlinear optical absorption effects also play a smaller but significant role in prolonging the warming. In effect, dampening factors that slow temperature increase during periods of increasing concentration also slow the loss of energy from the Earth's climate system if radiative forcing is reduced. Approaches to climate change mitigation options through reduction of greenhouse gas or aerosol emissions therefore should not be expected to decrease climate change impacts as rapidly as the gas or aerosol lifetime, even for short-lived species; such actions can have their greatest effect if undertaken soon enough to avoid transfer of heat to the deep ocean.

Contributions of stratospheric water vapor to decadal changes in the rate of global warming.

Stratospheric water vapor concentrations decreased by about 10% after the year 2000. Here we show that this acted to slow the rate of increase in global surface temperature over 2000-2009 by about 25% compared to that which would have occurred due only to carbon dioxide and other greenhouse gases. More limited data suggest that stratospheric water vapor probably increased between 1980 and 2000, which would have enhanced the decadal rate of surface warming during the 1990s by about 30% as compared to estimates neglecting this change. These findings show that stratospheric water vapor is an important driver of decadal global surface climate change.

Photodissociation dynamics of IBr(-)(CO(2))(n), n<15.

We report the ionic photoproducts produced following photoexcitation of mass selected IBr(-)(CO(2))(n), n=0-14, cluster ions at 790 and 355 nm. These wavelengths provide single state excitation to two dissociative states, corresponding to the A(') (2)Pi(1/2) and B 2 (2)Sigma(1/2) (+) states of the IBr(-) chromophore. Excitation of these states in IBr(-) leads to production of I(-)+Br and Br(-)+I( *), respectively. Potential energy curves for the six lowest electronic states of IBr(-) are calculated, together with structures for IBr(-)(CO(2))(n), n=1-14. Translational energy release measurements on photodissociated IBr(-) determine the I-Br(-) bond strength to be 1.10+/-0.04 eV; related measurements characterize the A(') (2)Pi(1/2)<--X (2)Sigma(1/2) (+) absorption band. Photodissociation product distributions are measured as a function of cluster size following excitation to the A(') (2)Pi(1/2) and B 2 (2)Sigma(1/2) (+) states. The solvent is shown to drive processes such as spin-orbit relaxation, charge transfer, recombination, and vibrational relaxation on the ground electronic state. Following excitation to the A(') (2)Pi(1/2) electronic state, IBr(-)(CO(2))(n) exhibits size-dependent cage fractions remarkably similar to those observed for I(2) (-)(CO(2))(n). In contrast, excitation to the B 2 (2)Sigma(1/2) (+) state shows extensive trapping in excited states that dominates the recombination behavior for all cluster sizes we investigated. Finally, a pump-probe experiment on IBr(-)(CO(2))(8) determines the time required for recombination on the ground state following excitation to the A(') state. While the photofragmentation experiments establish 100% recombination in the ground electronic state for this and larger IBr(-) cluster ions, the time required for recombination is found to be approximately 5 ns, some three orders of magnitude longer than observed for the analogous I(2) (-) cluster ion. Comparisons are made with similar experiments carried out on I(2) (-)(CO(2))(n) and ICl(-)(CO(2))(n) cluster ions.

Time resolved solvent rearrangement dynamics.

Ultrafast pump-probe studies of I2- recombination in size-selected I2- (CO2)n cluster ions demonstrate long time coherent motions in size-selected clusters and the resulting non-statistical energy flow in the cluster. For I2- photodissociated to produce either I- + I or I- + I*, we identify a solvent-driven energy transfer process without a condensed phase counterpart. The mechanism involved is a Marcus-like solvent-driven curve crossing, with the driving force arising from asymmetric solvation, not just from solvent orientation. By substituting another halogen for one I atom, we "break" the I2- symmetry, and thus obtain direct information on the electron transfer process. New experiments on IBr- (CO2)n photodissociation products confirm the behavior suspected in the I2- studies. Time-resolved experiments on IBr- and theoretical modeling of the dynamics provide quantitative information on the multiple curve crossings encountered in the recombination process. In related investigations, femtosecond negative ion-neutral-positive ion charge reversal apparatus is employed to investigate transient neutral species evolving along a reaction coordinate. We report studies of the rearrangement dynamics of Cu(OH2) produced by photodetachment of the corresponding anion. Following a controlled delay period, a second ultrafast tunable laser pulse initiates resonant multiphoton photoionization of the time-evolving Cu...OH2 complex. The time-resolved Cu+ and Cu+(OH2) signals provide information both on the prompt dissociation of the complex and on energy redistribution between internal rotational and radial modes of the evolving complex. Calculations of the time evolution of the anion geometric configuration on the neutral potential energy surface yield deeper insight into the nature of the rearrangement process and the energy flow within the complex.