Processing of English words with fine acoustic contrasts and simple tones: A mismatch negativity study

The purpose of this study was to compare the robustness of the event-related potential (ERP) response, called the mismatch negativity (MMN), when elicited by simple tone stimuli (differing in frequency, duration, or intensity) and speech stimuli (CV nonword contrast /de:/ vs. /ge:/ and CV word contrast /deI/ vs. /geI/). The study was conducted using 30 young adult subjects (Groups A and B; n = 15 each). The speech stimuli were presented to Group A at a stimulus onset asynchrony (SOA) of 610 msec and to Group B at an SOA of 900 msec. The tone stimuli were presented to both groups at an SOA of 610 msec. MMN responses were elicited by the simple tone stimuli (66.7%-96.7% of subjects with MMN "present," or significantly different from zero, p < 0.05) but not the speech stimuli (10% subjects with MMN present for nonwords, 10% for words). The length of the SOA (610 msec or 900 msec) had no effect on the ability to obtain consistent MMN responses to the speech stimuli. The results indicated a lack of robust MMN elicited by speech stimuli with fine acoustic contrasts under carefully controlled methodological conditions. The implications of these results are discussed in relation to conflicting reports in the literature of speech-elicited MMNs, and the importance of appropriate methodological design in MMN studies investigating speech processing in normal and pathological populations.

The mismatch negativity (MMN) response to complex tones and spoken words in individuals with aphasia

Background: The mismatch negativity (MMN) is a fronto-centrally distributed event-related potential (ERP) that is elicited by any discriminable auditory change. It is an ideal neurophysiological tool for measuring the auditory processing skills of individuals with aphasia because it can be elicited even in the absence of attention. Previous MMN studies have shown that acoustic processing of tone or pitch deviance is relatively preserved in aphasia, whereas the basic acoustic processing of speech stimuli can be impaired (e.g., auditory discrimination). However, no MMN study has yet investigated the higher levels of auditory processing, such as language-specific phonological and/or lexical processing, in individuals with aphasia. Aims: The aim of the current study was to investigate the MMN response of normal and language-disordered subjects to tone stimuli and speech stimuli that incorporate the basic auditory processing (acoustic, acoustic-phonetic) levels of non-speech and speech sound processing, and also the language-specific phonological and lexical levels of spoken word processing. Furthermore, this study aimed to correlate the aphasic MMN data with language performance on a variety of tasks specifically targeted at the different levels of spoken word processing. Methods M Procedures: Six adults with aphasia (71.7 years +/- 3.0) and six healthy age-, gender-, and education-matched controls (72.2 years +/- 5.4) participated in the study. All subjects were right-handed and native speakers of English. Each subject was presented with complex harmonic tone stimuli, differing in pitch or duration, and consonant-vowel (CV) speech stimuli (non-word /de:/versus real world/deI/). The probability of the deviant for each tone or speech contrast was 10%. The subjects were also presented with the same stimuli in behavioural discrimination tasks, and were administered a language assessment battery to measure their auditory comprehension skills. Outcomes O Results: The aphasic subjects demonstrated attenuated MMN responses to complex tone duration deviance and to speech stimuli (words and non-words), and their responses to the frequency, duration, and real word deviant stimuli were found to strongly correlate with performance on the auditory comprehension section of the Western Aphasia Battery (WAB). Furthermore, deficits in attentional lexical decision skills demonstrated by the aphasic subjects correlated with a word-related enhancement demonstrated during the automatic MMN paradigm, providing evidence to support the word advantage effect, thought to reflect the activation of language-specific memory traces in the brain for words. Conclusions: These results indicate that the MMN may be used as a technique for investigating general and more specific auditory comprehension skills of individuals with aphasia, using speech and/or non-speech stimuli, independent of the individual's attention. The combined use of the objective MMN technique and current clinical language assessments may result in improved rehabilitative management of aphasic individuals.

Spectral pattern, grouping, and the pitches of complex tones and their components

Harmonically related components are typically heard as a unified entity with a rich timbre and a pitch corresponding to the fundamental frequency. Mistuning a component generally has four consequences: (i) the global pitch of the complex shifts in the same direction as the mistuning; (ii) the component makes a reduced contribution to global pitch; (iii) the component is heard out as a separate sound with a pure timbre; (iv) its pitch differs from that of a pure tone of equal frequency in a small but systematic way. Local interactions between neighbouring components cannot explain these effects; instead they are usually explained in terms of the global operation of a single harmonic-template mechanism. However, several observations indicate that separate mechanisms govern the selection of spectral components for perceptual fusion and for the computation of global pitch. First, an increase in mistuning causes a harmonic to be heard out before it begins to be excluded from the computation of global pitch. Second, a single even harmonic added to an odd-harmonic complex is typically more salient than its odd neighbours. Third, the mistuning of a component in frequency-shifted stimuli, or stimuli with a moderate spectral stretch, results in changes in salience and component pitch like those seen for harmonic stimuli. Fourth, the global pitch of frequency-shifted stimuli is predicted well by the weighted fit of a harmonic template, but, with the exception of the lowest component, the fusion of individual partials for shifted stimuli is best predicted by the common pattern of spectral spacing. Fifth, our sensitivity to spectral pattern is surprisingly resistant to random variations in component spacing induced by applying mistunings to several harmonics at once. These findings are evaluated in the context of an autocorrelogram model of the proposed pitch/grouping dissociation. © S. Hirzel Verlag · EAA.

Asynchrony and the grouping of vowel components:captor tones revisited

Asynchrony is an important grouping cue for separating sound mixtures. A harmonic incremented in level makes a reduced contribution to vowel timbre when it begins before the other components. This contribution can be partly restored by adding a captor tone in synchrony with, and one octave above, the leading portion of the incremented harmonic [Darwin and Sutherland, Q. J. Exp. Psychol. A 36, 193-208 (1984)]. The captor is too remote to evoke adaptation in peripheral channels tuned to the incremented harmonic, and so the restoration effect is usually attributed to the grouping of the leading portion with the captor. However, results are presented that contradict this interpretation. Captor efficacy does not depend on a common onset, or harmonic relations, with the leading component. Rather, captor efficacy is influenced by frequency separation, and extends to about 1.5 oct above the leading component. Below this cutoff, the captor effect is equivalent to attenuating the leading portion of the incremented harmonic by about 6 dB. These results indicate that high-level grouping does not govern the captor effect. Instead, it is proposed that the partial restoration of the contribution of an asynchronous component to vowel timbre depends on broadband inhibition within the central auditory system. © 2006 Acoustical Society of America.

Build-up of the tendency to segregate auditory streams:resetting effects of single deviant tones

The tendency to hear a sequence of alternating low (L) and high (H) frequency tones as two streams can be increased by a preceding induction sequence, even one composed only of same-frequency tones. Four experiments used such an induction sequence (10 identical L tones) to promote segregation in a shorter test sequence comprising L and H tones. Previous studies have shown that the build-up of stream segregation is usually reduced greatly when a sudden change in acoustic properties distinguishes all of the induction tones from their test-sequence counterparts. Experiment 1 showed that a single deviant tone, created by altering the final inducer (in frequency, level, duration, or replacement with silence) reduced reported segregation, often substantially. Experiment 2 partially replicated this finding, using changes in temporal discrimination as a measure of streaming. Experiments 3 and 4 varied the size of a frequency change applied to the deviant tone; the extent of resetting varied with size only gradually. The results suggest that resetting begins to occur once the change is large enough to be noticeable. Since the prior inducers always remained unaltered in the deviant-tone conditions, it is proposed that a single change actively resets the build-up evoked by the induction sequence.

Clipping noise compensation for OFDMA systems

This paper presents an efficient low-complexity clipping noise compensation scheme for PAR reduced orthogonal frequency division multiple access (OFDMA) systems. Conventional clipping noise compensation schemes proposed for OFDM systems are decision directed schemes which use demodulated data symbols. Thus these schemes fail to deliver expected performance in OFDMA systems where multiple users share a single OFDM symbol and a specific user may only know his/her own modulation scheme. The proposed clipping noise estimation and compensation scheme does not require the knowledge of the demodulated symbols of the other users, making it very promising for OFDMA systems. It uses the equalized output and the reserved tones to reconstruct the signal by compensating the clipping noise. Simulation results show that the proposed scheme can significantly improve the system performance.

Media Studies: "Media, History and Society", and "Thinking Popular Culture".

“When cultural life is re-defined as a perpetual round of entertainments, when serious public conversation becomes a form of baby talk, when, in short, a people become an audience and their public business a vaudeville act, then a nation finds itself at risk.” (Postman) The dire tones of Postman quoted in Janet Cramer’s Media, History, Society: A Cultural History of US Media introduce one view that she canvasses, in the debate of the moment, as to where popular culture is heading in the digital age. This is canvassed, less systematically, in Thinking Popular Culture: War Terrorism and Writing by Tara Brabazon, who for example refers to concerns about a “crisis of critical language” that is bothering professionals—journalists and academics or elsewhere—and deplores the advent of the Internet, as a “flattening of expertise in digital environments”.

Supporting mature-aged students from a low socioeconomic background

The aim of the current study was to examine mature-aged student perceptions of university support services and barriers to study. Using a mixed methods approach, interviews and focus groups were conducted with mature-aged students to identify barriers to study, knowledge and use of current student support services, and suggestions to improve upon these services. From these data and an audit of university support services, an online survey was created to examine study barriers and patterns of support service use, as well as, perceptions of proposed support services not currently offered by the university within a larger sample of mature-aged students. Analysis of survey data indicated distinct patterns of barriers and support service use according to socioeconomic status as well as other demographic factors such as, age and enrolment status. Study findings are discussed in terms of generating support services for the retention of mature-aged students of low socioeconomic status and for the retention of mature-aged students in general.

Stability of the learning and development survey : findings for mature aged local government and private healthcare organisations.

This article investigates work related learning and development amongst mature aged workers from a lifespan developmental psychology perspective. The current study follows on from research regarding the construction and revision of the Learning and Development Survey (LDS; Tones & Pillay, 2008). Designed to measure adaptive development for work related learning, the revised LDS (R-LDS) encompasses goal selection, engagement and disengagement from individual and organisational perspectives. Previous survey findings from a mixed age sample of local government workers suggest that mature aged workers aged over 45 years are less likely to report engagement in learning and development goals than younger workers, which is partly due to insufficient opportunities at work. In the current paper, exploratory factor analysis was used to investigate responses to the R-LDS amongst two groups of mature aged workers from a local government (LG) and private healthcare (PH) organisation to determine the stability of the R-LDS. Organisational constraints to development accounted for almost a quarter of the variance in R-LDS scores for both samples, while remaining factors emerged in different orders for each data set. Organisational opportunities for development explained about 17% of the variance in R-LDS scores in the LG sample, while the individual goal disengagement factor contributed a comparable proportion of variance to R-LDS scores for the PH sample. Findings from the current study indicate that opportunities for learning and development at work may be age structured and biased towards younger workers. Implications for professional practice are discussed and focus on improving the engagement of mature aged workers.

Transitional employment aspirations for bridging retirement : implications for training and development

Purpose: The aim of this study was to identify the transitional employment aspirations and training and development needs of older and younger workers at risk of early retirement due to limited education and/or employment in blue collar occupations. Design/ Methodology/ Approach: A computer based methodology was used to evaluate the demographic effects of gender, education level and occupation group on aspirations pertaining to transitional employment and training and development in a sample of over 1000 Local Government employees. Findings: Older blue collar, secondary school educated and younger workers were less interested in transitional employment than older workers with higher levels of education or from white collar backgrounds. The early retirement risk factors of blue collar work and secondary school education had a more limited effect on perceived training and development needs for older workers. However for younger workers, these risk factors provided the impetus to undertake training to move into less physically demanding or more challenging roles as their careers progressed. Practical Implications: Via the identification of education level and occupation types groups’ transitional employment aspirations and perceptions of preparatory training and development within younger and older cohorts, long term strategies to develop and retain staff may be formulated. Originality/ Value: Past studies of transitional employment have rarely included younger workers or older workers at risk of early retirement. Preparatory training and development for transitional employment roles has not been considered in the literature.

Supporting the mature aged workforce

This article presents findings from an Australian research project regarding management of the mature aged workforce and ageing demographic issues. Semi structured interviews were used to discuss perceptions of older workers, ageing demography, informal work practices, formal work practices and business development. The sample included 25 employees from three local governments from the Queensland State in Australia. Four main themes emerged from the analysis regarding the current setting. These were: (1) Despite negative stereotyping, respondents had a positive view of older workers, (2) Age management was more of an issue for the outdoor workforce due to declines in physiological capacities associated with aging, (3) The overarching policy framework within the local councils was age neutral; and (4) Informal age management strategies existed at the discretion of the respective managers and section heads. An age conscious and forethought workforce plan was viewed as the next step towards a formal age management strategy. The findings indicate that mentoring, training and flexible work options to retain staff and to retain corporate knowledge may be some of the options for the future

Patterns of engagement in workplace learning amongst employees from social sectors

Continuous learning and development has become increasingly important in the information age. However, employees with limited formal education in lower status occupations may be disadvantaged in their opportunities for development, as their jobs tend to require more limited knowledge and skills. In mature age, such workers may be subject to cumulative disadvantage with respect to work related learning and development, as well as negative stereotyping. This thesis concerns work related learning and development from a lifespan development psychology perspective. Development across the lifespan is grounded in biocultural co-constructivism. That is, the reciprocal influences of the individual and environment produce change in the individual. Existing theories and models of adaptive development attempt to explain how developmental resources are allocated across the lifespan. These included the Meta- theory of Selective Optimisation with Compensation, Dual Process Model of Self Regulation, and Developmental Regulation via Optimisation and Primary and Secondary Control. These models were integrated to create the Model of Adaptive Development for Work Related Learning. The Learning and Development Survey (LDS) was constructed to measure the hypothesised processes of adaptive development for work related learning, which were individual goal selection, individual goal engagement, individual goal disengagement, organisational opportunities (selection and engagement), and organisational constraints. Data collection was undertaken in two phases: the pilot study and the main study. The objective of the pilot study was to test the LDS on a target population of 112 employees from a local government organisation. Exploratory factor analysis reduced the pilot version of the survey to 38 items encompassing eight constructs which covered the processes of the model of adaptive development for work related learning. In the main study, the Revised Learning and Development Survey (R-LDS) was administered to another group of 137 employees from the local government organisation, as well as 110 employees from a private healthcare organisation. The purpose of the main study was to validate the R-LDS on two different groups to provide evidence of stability, and compare survey scores according to age and occupational status to determine construct validity. Findings from the main study indicated that only four constructs of the R-LDS were stable, which were organisational opportunities – selection, individual goal engagement, organisational constraints – disengagement and organisational opportunities – engagement. In addition, MANOVA studies revealed that the demographic variables affected organisational opportunities and constraints in the workplace, although individual goal engagement was not influenced by age. The findings from the pilot and main study partially supported the model of adaptive development for work related learning. Given that only four factors displayed adequate reliability in terms of internal consistency and stability, the findings suggest that individual goal selection and individual goal disengagement are less relevant to work related learning and development. Some recent research which emerged during the course of the current study has suggested that individual goal selection and individual goal disengagement are more relevant when goal achievement is impeded by biological constraints such as ageing. However, correlations between the retained factors support the model of adaptive development for work related learning, and represent the role of biocultural co-constructivism in development. Individual goal engagement was positively correlated with both opportunity factors (selection and engagement), while organisational constraints – disengagement was negatively correlated with organisational opportunities – selection. Demographic findings indicated that higher occupational status was associated with more opportunities for development. Age was associated with fewer opportunities or greater constraints for development, especially for lower status workers.

Training and development for transitional employment in mature-aged manual workers

The purpose of the current article was to explore perceptions of transitional employment and training and development amongst blue collar workers employed in technical, trade, operations or physical and labour-intensive occupations within the local government system.