The behavioral masking level difference (MLD) has been established and incorporated into the central auditory processing test battery. Behavioral MLD literature states that the site of origin along the central auditory pathway is in the brainstem region. However, there has been some controversy when electrophysiologic measures have been performed during these types of behavioral MLD paradigms. Most electrophysiologic studies have focused on the late latency response (LLR) using small sample sizes (i.e. 10 subjects), and concluded that the origin of the MLD is cortical in nature. / The purpose of this study was to investigate and provide additional information, using a larger sample size (33 subjects), on the electrophysiologic MLD measures of the auditory brainstem response (ABR), middle latency response (MLR), and late latency response (LLR). Auditory evoked potential wave latencies and amplitudes were measured under both competing (broadband masker) and noncompeting conditions while using either a 500 Hz tone burst (3 msec rise/fall time with no plateau) or click signal. The phase of the signal was adjusted to be either in-phase or 180$\sp\circ$ out-of-phase at one ear. Behavioral MLDs were obtained beforehand using the identical stimuli as used during the evoked potential tests. A minimum 10 dB behavioral MLD was required. / Statistical significant differences, using ANOVA, were observed for in-phase/out-of-phase N1-P1 wave amplitudes of the LLR during competing conditions. No differences were observed for the MLR or the ABR during the same test conditions. However, significant differences were seen for waves I and V amplitudes during the noncompeting condition (phase difference) in the ABR. It was concluded that the only electrophysiologic measure showing the central auditory pathways participation during the MLD phenomenon was in the cortical region. However, this research using a larger sample size found fewer significant differences in the cortical region than those reported by previous researchers suggesting that studies of this nature and variability should be interpreted with caution before specific conclusions are made. / Source: Dissertation Abstracts International, Volume: 54-07, Section: B, page: 3538. / Major Professor: Lloyd L. Price. / Thesis (Ph.D.)--The Florida State University, 1993.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_76975 |
| Contributors | Franklin, Thomas Claiborne., Florida State University |
| Source Sets | Florida State University |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | 165 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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