Short-Wavelength Light-Blocking Eyeglasses Attenuate Symptoms of Eye Fatigue

Purpose: The purpose of this study was to determine whether subjects who wear short wavelength–blocking eyeglasses during computer tasks exhibit less visual fatigue and report fewer symptoms of visual discomfort than subjects wearing eyeglasses with clear lenses.Methods: A total of 36 healthy subjects (20 male; 16 female) was randomized to wearing no-block, low-blocking, or high-blocking eyeglasses while performing a 2-hour computer task. A masked grader measured critical flicker fusion frequency (CFF) as a metric of eye fatigue and evaluated symptoms of eye strain with a 15-item questionnaire before and after computer use.Results: We found that the change in CFF after the computer task was significantly more positive (i.e., less eye fatigue) in the high-block versus the no-block (P = 0.027) and low-block (P = 0.008) groups. Moreover, random assignment to the high-block group but not to the low-block group predicted a more positive change in CFF (i.e., less eye fatigue) following the computer task (adjusted β = 2.310; P = 0.002). Additionally, subjects wearing high-blocking eyeglasses reported significantly less feeling pain around/inside the eye (P = 0.0063), less feeling that the eyes were heavy (P = 0.0189), and less feeling that the eyes were itchy (P = 0.0043) following the computer task, when compared to subjects not wearing high-blocking lenses.Conclusions: Our results support the hypothesis that short-wavelength light-blocking eyeglasses may reduce eye strain associated with computer use based on a physiologic correlate of eye fatigue and on subjects\u27 reporting of symptoms typically associated with eye strain

Phonons and related properties of extended systems from density-functional perturbation theory

This article reviews the current status of lattice-dynamical calculations in crystals, using density-functional perturbation theory, with emphasis on the plane-wave pseudo-potential method. Several specialized topics are treated, including the implementation for metals, the calculation of the response to macroscopic electric fields and their relevance to long wave-length vibrations in polar materials, the response to strain deformations, and higher-order responses. The success of this methodology is demonstrated with a number of applications existing in the literature.Comment: 52 pages, 14 figures, submitted to Review of Modern Physic

Validity of rating scale measures of voice quality

The validity of perceptual measures of vocal quality has been neglected in studies of voice, which focus more commonly on rater reliability. Validity depends in part on reliability, because an unreliable test does not measure what it is intended to measure. However, traditional measures of rating reliability only partially represent interrater agreement, because they cannot reflect variations or patterns of agreement for specific voice samples. In this paper the likelihood that two raters would agree in their ratings of a single voice is examined, for each voice in five previously gathered data sets. Results do not support the continued assumption that traditional rating procedures produce useful indices of listeners' perceptions. Listeners agreed very poorly in the midrange of scales for breathiness and roughness, and mean ratings in the midrange of such scales did not represent the extent to which a voice possesses a quality, but served only to indicate that listeners disagreed. Techniques like analysis by synthesis or judgment of similarity avoid decomposing quality into constituent dimensions, and do not require a listener to compare an external stimulus to an unstable internal representation, thus decreasing the error in measures of quality. Modeling individual differences in perception can increase the variance accounted for in models of quality, further reducing the error in perceptual measures. Thus such techniques may provide valid alternatives to current approaches

Avaliação da nasalidade de fala na fissura labiopalatina

Objetivo Descrever os resultados da nasalidade de fala de indivíduos com fissura labiopalatina e comparar os achados de nasalidade estabelecidos por meio do julgamento perceptivo-auditivo realizado ao vivo com os achados estabelecidos por análise de gravações por juízes, em dois tipos de amostras de fala. Métodos O estudo envolveu a análise retrospectiva dos resultados de avaliações perceptivo-auditivas da nasalidade de fala realizadas ao vivo por uma fonoaudióloga e o julgamento prospectivo, por consenso de juízas de 100 gravações de amostras de fala, obtidas durante a produção de dois conjuntos de estímulos de fala: um com consoantes de alta pressão (CAP, n=100) e outro com consoantes de baixa pressão (CBP, n=100). Os dados pertenciam a pacientes de ambos os gêneros, com idades entre 5 e 12 anos, que tiveram a fissura labiopalatina operada por um mesmo cirurgião. Resultados A ausência de hipernasalidade foi constatada em 69% dos julgamentos ao vivo. Quando presente, a hipernasalidade leve foi constatada em 23% dos casos, enquanto a hipernasalidade moderada em 8%. Para os julgamentos das amostras gravadas, 50% foram identificadas com hipernasalidade durante a produção das amostras CAP e 62% durante a das amostras CBP. Diferença significativa foi encontrada entre o resultado do julgamento ao vivo e o julgamento pelas juízas nas amostras CAP. A concordância entre as modalidades de avaliação variou de 79% para as amostras CAP e 80% para as amostras CBP, sendo considerada moderada. Conclusão O julgamento perceptivo ao vivo da nasalidade de fala pode detectar melhor a ausência de hipernasalidade, seguida pela hipernasalidade de grau leve, em comparação com o julgamento realizado por juízes múltiplos, a partir de amostras gravadas. Contudo, tem a desvantagem de os dados não poderem ser reproduzidos, nem quantificados, nem compartilhados por outros membros da equipe

Perception of aperiodicity in pathological voice

Although jitter, shimmer, and noise acoustically characterize all voice signals, their perceptual importance in naturally produced pathological voices has not been established psychoacoustically. To determine the role of these attributes in the perception of vocal quality, listeners were asked to adjust levels of jitter, shimmer, and the noise-to-signal ratio in a speech synthesizer, so that synthetic voices matched naturally produced tokens. Results showed that, although listeners agreed well in their judgments of the noise-to-signal ratio, they did not agree with one another in their chosen settings for jitter and shimmer. Noise-dependent differences in listeners' ability to detect changes in amounts of jitter and shimmer implicate both listener insensitivity and inability to isolate jitter and shimmer as separate dimensions in the overall pattern of aperiodicity in a voice as causes of this poor agreement. These results suggest that jitter and shimmer are not useful as independent indices of perceived vocal quality, apart from their acoustic contributions to the overall pattern of spectrally shaped noise in a voice. (c) 2005 Acoustical Society of America