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THE DEVELOPMENT OF AUDITORY STEADY STATE RESPONSES
Auditory steady state responses and steady state evoked potentials (SSEPs) are the two most frequently used labels found in a survey of relevant literature to describe this “new” type of AEP. Other, less frequently used, terms are “steady state fields” (Pantev et al., 1996), “frequency following response” (Kuwada et al., 1986) and “envelope following response” (Dolphin & Mountain, 1993). Although there are some differences in their applications, the definitions of these terms boil down to more or less the same concept. The term ASSR and SSEP are commonly used interchangeably, but, Sininger and Cone-Wesson (2002) have concluded that ASSR has become the term of choice in recent years. This assessment can, however, not be accepted without a critical analysis of the uses and implications of the term ASSR as the name for a new auditory evoked potential. Such an analysis is provided below.
Critics of the term “response” argue that in conventional audiometry, this term is applied to instances where the patient reacts to a stimulus that is presented in the form of a sound. Schmulian (2002) also questions the use of the term “response” in relation to evoked potential methods, since electrical waves are measured without any regard to a conscious or voluntary response on the part of the subject (Goldstein & Aldrich, 1999). Notwithstanding this discrepancy, it seems that the use of the term ASSR has gained wide acceptance and it is therefore used in the rest of this study. In a clinical context, the term“response” would certainly be acceptable, as protocols are designed and recorded to establish a response, for example, at the threshold level. The AEP technique known as ASSR was discovered and developed at the University of Melbourne during the 1980s (ERA Systems Pty Ltd, 2000).
This clinical test system was preceded by research on human steady-state evoked potentials in the visual field (Picton et al., 2003). Galambos, Makerg and Talmachoff’s (1981) research provided the main impetus for extensive research into auditory steady state responses (Picton et al., 2003). Rance et. al. (1995) and Rance et al., (1998) indicate that ASSRs address the main shortcomings of ABR testing, in that ASSR is an alternative frequency-specific approach which does not suffer the spectral distortion problems associated with short-duration stimuli. ASSRs are periodic scalp potentials arising in response to regularly varying stimuli, such as a sinusoidal amplitude- and/or frequency-modulated tones (Rance et. al., 1998).
CHAPTER 1: INTRODUCTION
1.1 BACKGROUND
1.2 RATIONALE
1.3 PROBLEM STATEMENT
1.5 PURPOSE OF THE STUDY
1.6 CLARIFICATION OF TERMINOLOGY
1.7 OUTLINE OF THE STUDY
1.8 SUMMARY
CHAPTER 2: PSEUDOHYPACUSIS AND APPROPRIATE STRATEGIES TO DETECT AND QUANTIFY THE CONDITION
2.1 INTRODUCTION
2.2 DEFINITION OF PSEUDOHYPACUSIS
2.3 PREVALENCE AND ETIOLOGICAL FACTORS
2.4 AUDIOLOGICAL ASSESSMENT OF PSEUDOHYPACUSIS
2.5 SUMMARY
CHAPTER 3: ELECTROPHYSIOLOGICAL TESTS AND THEIR USE IN THE ASSESSMENT OF PSEUDOHYPACUSIS
3.1 INTRODUCTION
3.2 ELECTROPHYSIOLOGICAL (EP) TESTS
3.3 SUMMARY
CHAPTER 4: AUDITORY STEADY STATE RESPONSES (ASSR) AND PSEUDOHYPACUSIS
4.1 INTRODUCTION
4.2 THE DEVELOPMENT OF AUDITORY STEADY STATE RESPONSES
4.3 RESEARCH FINDINGS WITH ASSRs
4.4 SUMMARY
CHAPTER 5: RESEARCH METHODS
5.1 INTRODUCTION
5.2 AIMS OF THE RESEARCH
5.3 RESEARCH PLAN
5.4 ETHICAL CONSIDERATIONS
5.5 SUBJECTS
5.6 MATERIAL AND APPARATUS.
5.7 DATA COLLECTION PROCEDURES
5.8 DATA ANALYSIS PROCEDURES
5.9 SUMMARY
CHAPTER 6: RESULTS
CHAPTER 7: CONCLUSIONS AND RECOMMENDATIONS.
BIBLIOGRAPHY
