The purpose of this study is to investigate the flow of nonsymbolic auditory information in humans. To achieve this goal the observer adjusts the loudness of a Gaussian noise (GN) signal to match the perceived intensity of an electrodermal stimulus (EDS), a cross-modality matching task. The loudness of the GN and the voltage of the EDS mere maintained within the observer's (O's) sensory probabilistic zone. The sensory probabilistic zone is a range of stimulus intensity from somewhere above "no detection" to "100% detection". The independent variable is a binary condition in that it consisted of catch trials of the time and the remaining time of an EDS at a given intensity (previously determined at an intensity that elicited a response 50% of the time). Consequently, the O's adjustment of the GN reflected his decision-making processes, analysed by signal detection theory and cybernetics. Experiment one demonstrated that neither practice nor the experimenter influenced the O's performance. Also, there are no residual carry-over effects. The 0 has difficulty assigning relative value to the auditory signals and has little or no difficulty in combining, organizing or co-ordinating the auditory information. The second experiment demonstrated that the O's difficulty in assigning relative value to the signals is due to a short memory retention of the nonsymbolic auditory signals (half-life of less than a second). However, verbal confidence ratings (VCRs) add persistency to the auditory memory (echoic memory), its half-life is extended to about 3.1 seconds. The VCR has a half-life of about four seconds. Experiment three demonstrated that nonsymbolic auditory information processing is not affected by interfering signals. From a cybernetic model of the results it is concluded that nonsymbolic auditory information is processed by a filtered, single channel, series processor. Persistency is added to the system's memory component by an interaction between the auditory (echoic) memory and the conceptual symbolic system (VCR).

This thesis examines three issues which are of importance in the study of auditory word recognition: the phonological unit which is used to access representations in the mental lexicon; the extent to which hearers can rely on words being identified before their acoustic offsets; and the role of context in auditory word recognition. Three hypotheses which are based on the predictions of the Cohort Model (Marslen-Wilson and Tyler 1980) are tested experimentally using the gating paradigm. First, the phonological access hypothesis claims that word onsets, rather than any other part of the word, are used to access representations in the mental lexicon. An alternative candidate which has been proposed as the initiator of lexical access is the stressed syllable. Second, the early recognition hypothesis states that polysyllabic words, and the majority of words heard in context, will be recognised before their acoustic offsets. Finally, the context-free hypothesis predicts that during the initial stages of the processing of words, no effects of context will be discernible. Experiment 1 tests all three predictions by manipulating aspects of carefully articulated, read speech. First, examination of the gating responses from three context conditions offers no support for the context-free hypothesis. Second, the high number of words which are identified before their acoustic offsets is consistent with the early recognition hypothesis. Finally, the phonological access hypothesis is tested by manipulation of the stress patterns of stimuli. The dependent variables which are examined relate to the processes of lexical access and lexical retrieval; stress differences are found on access measures but not on those relating to retrieval. When the experiment is replicated with a group of subjects whose level of literacy is lower than that of the undergraduates who took part in the original experiment, differences are found in measures relating to contextual processing. Experiment 2 continues to examine the phonological access hypothesis, by manipulating speech style (read versus conversational) as well as stress pattern. Gated words, excised from the speech of six speakers, are presented in isolation. Words excised from read speech and words stressed on the first syllable elicit a greater number of responses which match the stimuli than conversational tokens and words with unstressed initial syllables. Intelligibility differences among the four conditions are also reported. Experiment 3 aims to investigate the processing of read and spontaneous tokens heard in context, while maintaining the manipulation of stress pattern. A subset of the words from Experiment 2 are presented in their original sentence contexts: the test words themselves, plus up to three subsequent words, are gated. Although the presence of preceding context generally enhances intelligibility, some words remain unrecognised by the end of the third subsequent word. An interaction between stress and speech style may be explained in terms of the unintelligibility of the preceding context. Several issues arising from Experiments 1, 2 and 3 are considered further. The characteristics of words which fail to be recognised before their offsets are examined using the statistical technique of regression; the contributions of phonetic and phonological aspects of stressed syllables are assessed; and a further experiment is reported which explores top-down processing in spontaneous speech, and which offers support for the interpretation of the results of Experiment 3 offered earlier.

This thesis comprises of three sections, a literature review, research report and a critical appraisal. Section 1: The review critically examined the existing literature surrounding integration and sealing-over recovery styles in psychosis. The main body of the literature review explored the development of two recovery styles, prognostic indicators, engagement with mental health services and psychological therapy. Implications for future research were discussed.

In the present study, dichotic listening performance of two-year-old children was investigated. Single pairs of words were presented dichoticaly to thirty-one children between GA 2-0-12 and 3-1-20. Each subject was asked to point to pictures of what he had heard. For each pair of words presented, a subject was shown three pictures, which corresponded to the two stimulus words and a foil word. Differences between number of correct responses for each ear were evaluated by means of a t test. Words presented to the right ear were more efficiently recalled than words presented to the left ear, in this age group , which suggests that the left hemisphere has achieved some degree of dominance for language by age two. No statisticaly significant differences were noted, in degree of right ear advantage, between males and females. When studies using school age and adult subjects are compared, it appears that the right ear advantage does not change in magnitude or direction from age two until adulthood. Results of the present investigation are discussed in relation to existing theories of the development of cerebral lateralization. An attempt was made to relate experimental results from dichotic listening,. EEG, and clinical studies. Limitations of the experiment, as wall as suggestions for further research, are discussed. / Medicine, Faculty of / Audiology and Speech Sciences, School of / Graduate

This investigation studies the effect of phonation and of some activities eliciting middle-ear muscle contraction on high-intensity sound transmission in the normal human auditory system. For the most part it is concerned with the influence of phonation on TTS from a continuous pure-tone stimulus. The main experimental technique consisted of measuring subjects' hearing thresholds before and after a 5 min, 500-Hz, 118-dB SPL exposure, this exposure being sometimes accompanied by the performance of a specific activity such as phonation. Threshold tracings were obtained by using a Békésy-type procedure, and threshold was measured at 7 times after cessation of the exposure tone. Analysis of the results indicates that TTS from phonation (humming) during exposure was significantly less than TTS from the exposure tone without any supplementary activity, for a variety of humming activities: humming at 125 Hz (males) or 250 Hz (females); humming loudly at these same frequencies; or humming at 250 Hz (males) or 500 Hz (females). TTS from humming loudly and humming at the higher frequencies was consistently, although not significantly, less than TTS from humming at the lower frequencies. For females, phonation (humming during exposure was more effective in decreasing TTS than for males. Repeatedly turning the head during exposure, which is believed to elicit MEM contraction, resulted in less TTS than no activity during exposure. Similar slight decreases in TTS were observed when the following activities which elicit middle-ear muscle contraction were performed during exposure: chewing, smiling, swallowing. Listening to recorded humming during exposure did not significantly alter TTS from the exposure. The activity of exhaling after preparing to hum did not significantly alter TTS from the exposure. In addition to the TTS studies, measurements of acoustic impedance during the exposure tone and of acoustic reflex thresholds were obtained. Various hypotheses concerning causes for the reduced TTS from phonation during exposure are discussed. Attenuation provided by middle-ear muscle contraction during phonation does not appear sufficient to decrease TTS to the extent that humming does. Sound may be attenuated by inefficient stapes vibration during phonation and TTS may therefore be reduced. Two other possibilities are suggested to account for the TTS decrease: interference between humming and the exposure tone; and interference (by humming) with the central control of middle-ear muscle activity. More evidence will be necessary to satisfactorily determine which, if any, of these mechanisms is actually in effect. / Medicine, Faculty of / Audiology and Speech Sciences, School of / Graduate

The primary auditory cortex (area AI) plays an important role in the localization of static sound sources. However, little is known concerning how it processes information about sound source motion. This study was undertaken to investigate the responses of single neurons in the primary auditory cortex of the cat to correlates of auditory motion in space. Diotic and dichotic changes in sound intensity presented through earphones simulated auditory motion in four directions: toward and away from the receiver along the midline, into the ipsilateral hemifield and into the contralateral hemifield. Different rates of intensity change simulated sound source velocity. Results indicate that AI neurons can be highly selective to intensity correlates of auditory motion. Three major classes of neurons were encountered: neurons sensitive to motion toward or away from the receiver, neurons sensitive to ipsilateral- or contralateral-directed motion, and monaural-like neurons. The different classes of direction-selective neurons were spatially segregated from each other and appeared to occur in clusters or columns in the cortex. In addition to their selectivity for different directions of simulated sound source motion, AI neurons also responded selectively to the rate and excursion of intensity changes, a correlate of sound source velocity. The major determinants of direction and velocity selectivity were interactions between the following response properties of AI neurons: binaural interaction type, ear dominance, on/off responses, and monotonicity of rate/intensity function. These findings suggest that neural processing of auditory motion may involve neural mechanisms distinct from those involved in static sound localization, and indicate that some neurons in the primary auditory cortex may be part of a specialized motion-detecting mechanism in the auditory system. / Arts, Faculty of / Psychology, Department of / Graduate

ABSTRACT Background: Accessibility to reliable and cost-effective assessment of auditory processing skills is limited in South Africa. With the development of tele-audiology, tools such as the Feather Squadron (FS) application have been developed to make this form of assessment more cost-effective and accessible. Purpose: To determine whether the performance on the FS correlates with performance on certain traditional assessment tasks, viz. Frequency Pattern Test (FPT) and Dichotic Digits Test (DDT), to establish its relevance in a South African population. Design: A retrospective, within-subject, comparative design was used. Study Sample: 66 South African participants, aged between 8 and 9 years of age and educated in English. Method: The FS, FPT and DDT were administered following a peripheral hearing assessment. The data were considered in two ways: Firstly, by comparing whether in each instance the participant had scored either at or below -2SD or whether they had scored above-2SD on the subtests of the FS and compared these scores to the same traditional tests, and secondly, by comparing the Z-scores obtained on the FS versus the Z-scores obtained on the same traditional test by applying a double arcsine transformation. Results: Using the -2SD criteria yielded no significant association when comparing the Dichotic Digits FS vs Dichotic Digits traditional test, or when comparing Tonal-Pattern Temporal Processing FS vs FPT in the humming or labelling conditions. Using the Z-score comparison, a statistically significant correlation was obtained when comparing the Tonal-Pattern Temporal Processing FS vs FPT, labelling condition and Dichotic Double-Words FS (linguistic) vs DDT. Conclusions: There is sufficient early evidence to suggest a statistically significant correlation between certain subtests of the FS with traditional tests of auditory processing to merit its use in the South African population. Further, using the broad pass/fail criteria of -2SD lacks the precision to adequately identify patterns of response and may need to be re-evaluated. Key Words: Feather Squadron, dichotic digits, frequency pattern, auditory processing, South Africa. / Dissertation (MA (Audiology)) University of Pretoria, 2020. / 2022/12/31 / Speech-Language Pathology and Audiology / MA (Audiology) / Restricted

The aim of this study was to investigate whether music influences human life before birth. In order to determine the existence and character of music in the uterine acoustic environment, a study was conducted involving the insertion of a hydrophone through the cervix, next to the fetal head. The investigation was conducted on eight women in early labour. The average residual uterine sound of the eight subjects was measured at 65 dBA (A-weighted) re 20 µ.Pa in a 1 O KHz band, RMS averaged over 32-second records. Above this emerged the maternal voice, an external female voice and a male voice presented at approximately 65 dB (linear weighted). Pure tones between 50 Hz and 1 O KHz and orchestral music, all presented at 80 dB (linear weighted), were also shown to emerge above the residual uterine sound. Attenuation of external sound was observed to vary as a function of frequency, with less attenuation of lower frequencies. It was determined that the music was transmitted into the uterus without sufficient distortion to significantly alter the recognisable characteristics of the music. The fetal heart rate (FHA) response to a music stimulus (MS) and a vibroacoustic stimulus (VS) was measured in 40 subjects. Gestational age of the fetuses ranged from 32 to 42 weeks. The study included a control period with no acoustic stimulation; a period with the presentation of 5 music stimuli; and a period with the presentation of 5 vibroacoustic stimuli. A change in the FHA of 15 beats per minute or greater, lasting 15 seconds and occurring within 15 seconds of at least 2 of the 5 stimuli (or a tachycardia of greater than 15 beats per minute above the resting baseline, sustained for one minute or longer) was considered to be a positive response. The MS elicited a positive response in 35 of the fetuses (the 5 non-responses occurring in a period of low FHA variability) and all 40 fetuses responded to the VS (regardless of arousal state). In the third study, mothers attending childbirth education classes volunteered to listen to a prescribed music excerpt twice daily from the 34th week of pregnancy. Ten neonates (all clinically normal) were tested betw~en the 2nd and 5th day after birth. Investigators observed the effect of two music sti:Tiuli, the prescribed stimulus and a non-prescribed stimulus, on neonatal sucking of a non-nutritive nipple. A five-minute control period with no stimulation was compared with a ten-minute period during which two music stimuli were presented. By random allocation, either the prescribed music stimulus (PM) or the nonprescribed music (NM) was presented contingent upon sucking pressure. If a sucking burst was initiated, the PM stimulus was activated. On cessation of sucking, the NM stimulus was activated. Randomly, the procedure would be reversed for some of the subjects, where initiation of sucking activated the NM stimulus and cessation of sucking activated the PM stimulus. It was determined that the inter-burst intervals during the music period were significantly extended when coinciding with the PM stimulus and significantly shortened when coinciding with the NM stimulus.The studies indicated that music is transmitted into the uterus with insufficient distortion to alter the character of the music; that the normal fetus responds to a music stimulus from at least the 32nd week of gestation; and that the neonate alters the normal sucking pattern to activate longer periods of a music stimulus which has been repeatedly presented during the intrauterine stage and shorter periods of a novel music stimulus.

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