This study evaluated a time-restricted region-suppressed event-related synthetic aperture magnetoencephalography (TRRS-ER-SAM) beamformer algorithm against equivalent current dipole (ECD), and event-related synthetic aperture magnetoencephalography (ER-SAM) post-processing methods for magnetoencephalography data. This evaluation was done numerically and with auditory evoked field (AEF) data elicited by binaurally presented 500 Hz tones. The TRRS-ER-SAM beamformer demonstrated robustness to noise, and the ability to handle coherent sources. The TRRS-ER-SAM algorithm was then applied to a study of N1m AEFs in 8 subjects aged 12-25 years. The study examined the effects of age, stimulus frequency, and right-sided monaural versus binaural stimulation on the N1m location, amplitude, and latency. It was found that age affected the N1m latency; stimulus frequency affected the N1m location, amplitude, and latency; and monaural versus binaural stimulation affected the N1m amplitude. In the context of these effects, the auditory pathway structure and neurophysiological changes due to maturation were discussed.

Current theories of auditory attention are largely based upon studies examining either the presentation of a single auditory stimulus or requiring the identification and labeling of stimuli presented sequentially. Whether or not these theories apply in more complex ecologically-valid environments where multiple sound sources are simultaneously active is still unknown. This study examined the pattern of neuromagnetic responses elicited when participants had to perform a search in an auditory language-based `scene` for a stimulus matching an imperative target held in working memory. The analysis of source waveforms revealed left lateralized patterns of activity that distinguished target present from target absent trials. Similar source waveform amplitudes were found when the target was presented in the left or right hemispace. The results suggest that auditory search for speech sounds engage a left lateralized process in the superior temporal gyrus.

Current theories of auditory attention are largely based upon studies examining either the presentation of a single auditory stimulus or requiring the identification and labeling of stimuli presented sequentially. Whether or not these theories apply in more complex ecologically-valid environments where multiple sound sources are simultaneously active is still unknown. This study examined the pattern of neuromagnetic responses elicited when participants had to perform a search in an auditory language-based `scene` for a stimulus matching an imperative target held in working memory. The analysis of source waveforms revealed left lateralized patterns of activity that distinguished target present from target absent trials. Similar source waveform amplitudes were found when the target was presented in the left or right hemispace. The results suggest that auditory search for speech sounds engage a left lateralized process in the superior temporal gyrus.

This study evaluated a time-restricted region-suppressed event-related synthetic aperture magnetoencephalography (TRRS-ER-SAM) beamformer algorithm against equivalent current dipole (ECD), and event-related synthetic aperture magnetoencephalography (ER-SAM) post-processing methods for magnetoencephalography data. This evaluation was done numerically and with auditory evoked field (AEF) data elicited by binaurally presented 500 Hz tones. The TRRS-ER-SAM beamformer demonstrated robustness to noise, and the ability to handle coherent sources. The TRRS-ER-SAM algorithm was then applied to a study of N1m AEFs in 8 subjects aged 12-25 years. The study examined the effects of age, stimulus frequency, and right-sided monaural versus binaural stimulation on the N1m location, amplitude, and latency. It was found that age affected the N1m latency; stimulus frequency affected the N1m location, amplitude, and latency; and monaural versus binaural stimulation affected the N1m amplitude. In the context of these effects, the auditory pathway structure and neurophysiological changes due to maturation were discussed.

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We are capable of effortlessly parsing a complex scene presented to us. In order to do this, we must segregate objects from each other and from the background. While this process has been extensively studied in vision science, it remains relatively less understood in auditory science. This thesis sought to characterize the neuroelectric correlates of auditory scene analysis using electroencephalography. Chapter 2 determined components evoked by first-order energy boundaries and second-order pitch boundaries. Chapter 3 determined components evoked by first-order and second-order discontinuous motion boundaries. Both of these chapters focused on analysis of event-related potential (ERP) waveforms and time-frequency analysis. In addition, these chapters investigated the contralateral nature of a negative ERP component. These results extend the current knowledge of auditory scene analysis by providing a starting point for discussing and characterizing first-order and second-order boundaries in an auditory scene. / x, 90 leaves : col. ill. ; 29 cm

Thesis (Au. D.)--Missouri State University, 2008. / "May 2008." Includes bibliographical references (leaves 49-53). Also available online.

Thesis--University of Jyväskylä, 1997. / Added t.p. with thesis statement inserted.

Thesis (M. (Communication Pathology))--University of Pretoria, 2005. / Includes bibliographical references.

Thesis--University of Jyväskylä, 1997. / Added t.p. with thesis statement inserted.