Pitch discrimination in optimal and suboptimal acoustic environments: electroencephalographic, magnetoencephalographic, and behavioral evidence

Pitch discrimination is a fundamental property of the human auditory system. Our understanding of pitch-discrimination mechanisms is important from both theoretical and clinical perspectives. The discrimination of spectrally complex sounds is crucial in the processing of music and speech. Current methods of cognitive neuroscience can track the brain processes underlying sound processing either with precise temporal (EEG and MEG) or spatial resolution (PET and fMRI). A combination of different techniques is therefore required in contemporary auditory research. One of the problems in comparing the EEG/MEG and fMRI methods, however, is the fMRI acoustic noise. In the present thesis, EEG and MEG in combination with behavioral techniques were used, first, to define the ERP correlates of automatic pitch discrimination across a wide frequency range in adults and neonates and, second, they were used to determine the effect of recorded acoustic fMRI noise on those adult ERP and ERF correlates during passive and active pitch discrimination. Pure tones and complex 3-harmonic sounds served as stimuli in the oddball and matching-to-sample paradigms. The results suggest that pitch discrimination in adults, as reflected by MMN latency, is most accurate in the 1000-2000 Hz frequency range, and that pitch discrimination is facilitated further by adding harmonics to the fundamental frequency. Newborn infants are able to discriminate a 20% frequency change in the 250-4000 Hz frequency range, whereas the discrimination of a 5% frequency change was unconfirmed. Furthermore, the effect of the fMRI gradient noise on the automatic processing of pitch change was more prominent for tones with frequencies exceeding 500 Hz, overlapping with the spectral maximum of the noise. When the fundamental frequency of the tones was lower than the spectral maximum of the noise, fMRI noise had no effect on MMN and P3a, whereas the noise delayed and suppressed N1 and exogenous N2. Noise also suppressed the N1 amplitude in a matching-to-sample working memory task. However, the task-related difference observed in the N1 component, suggesting a functional dissociation between the processing of spatial and non-spatial auditory information, was partially preserved in the noise condition. Noise hampered feature coding mechanisms more than it hampered the mechanisms of change detection, involuntary attention, and the segregation of the spatial and non-spatial domains of working-memory. The data presented in the thesis can be used to develop clinical ERP-based frequency-discrimination protocols and combined EEG and fMRI experimental paradigms.

A Comparison of the Implementation of the Employment Provisions of the Americans with Disabilities Act of 1990 (ADA) in the United States and the Disability Discrimination Act (DDA) 1995 in the United Kingdom

This summarizes the results of recently conducted surveys in the United States and Britain to assess employer response in each of these countries to their respective employment disability nondiscrimination legislation.

Griggs' Folly: An Essay on the Theory, Problems, and Origin of the Adverse Impact Definition of Employment Discrimination and a Recommendation for Reform

This Article examines the adverse impact theory of employment discrimination under Title VII. The author begins by discussing the development of adverse impact in the case law, and by scrutinizing its theoretical underpinnings. He demonstrates that Congress did not intend to mandate adoption of adverse impact theory when it established Title VII. The author then argues that the Courts have exceeded their authority under Title VII by embracing the theory of adverse impact. He concludes that the courts should therefore return to a narrower theory of employment discrimination, namely, a theory based on the legal concept of “intent.”

Disability in a Technology-Driven Workplace

New Internet and Web-based technology applications have meant significant cost and time efficiencies to many American businesses. However, many employers have not yet fully grasped the impact of these new information and communication technologies on applicants and employees with certain disabilities such as vision impairments, hearing problems or limited dexterity. Although not all applicants and employees who have a disability may experience IT-access problems, to select groups it can pose a needless barrier. The increasing dominance of IT in the workplace presents both a challenge and an opportunity for workers with disabilities and their employers. It will be up to HR professionals to ensure that Web-based HR processes and workplace technologies are accessible to their employees with disabilities. .

Portrait of Surgeon Major Dr. Meyer of Dueren (Rhineland) in military uniform Portraits Men

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Portrait of Surgeon Major Dr. Bing of Nuernberg in his military uniform Portraits Men

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