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Research paper thumbnail of Idiosyncratic sound systems of the South African Bantu languages: Research and clinical implications for speech-language pathologists and audiologists

The South African journal of communication disorders = Die Suid-Afrikaanse tydskrif vir Kommunikasieafwykings, 2014

The objective of this article is to create awareness amongst speech-language pathologists and aud... more The objective of this article is to create awareness amongst speech-language pathologists and audiologists in South Africa regarding the difference between the sound systems of Germanic languages and the sound systems of South African Bantu languages. A brief overview of the sound systems of two Bantu languages, namely isiZulu and Setswana, is provided. These two languages are representative of the Nguni language group and the Sotho group respectively.Consideration is given to the notion of language-specific symptoms of speech, language and hearing disorders in addition to universal symptoms. The possible impact of speech production, language and hearing disorders on the ability to produce and perceive speech in these languages, and the challenges that this holds for research and clinical practice, are pointed out.

Research paper thumbnail of What can speech production errors tell us about cross-linguistic processing in bilingual aphasia? Evidence from four English/Afrikaans bilingual individuals with aphasia

South African Journal of Communication Disorders, 2015

The aim of this study is contribute to clinical practice of bilinguals around the globe, as well ... more The aim of this study is contribute to clinical practice of bilinguals around the globe, as well as to add to our understanding of bilingual aphasia processing, by analysing confrontation naming data from four Afrikaans/English bilingual individuals with acquired aphasia due to a left hemisphere stroke. This is a case series analysis of four Afrikaans/English bilingual aphasic individuals following a left cerebrovascular accident. Error analysis of confrontation naming data in both languages was performed. Research questions were directed toward the between language differences in lexical retrieval abilities, types of errors produced and degree of cognate overlap. Three of the four participants showed significantly higher naming accuracy in first acquired language (L1) relative to the second acquired language (L2) and the largest proportion of error type for those three participants in both L1 and L2 was omission. One of the four participants (linguistically balanced) showed no between language accuracy difference. Regarding cognate overlap, there was a trend for higher accuracy for higher cognate words (compared to low). This study showed that naming performance in these four individuals was reflective of their relative language proficiency and use patterns prior to their stroke. These findings are consistent with the hierarchical model, in normal bilingual speakers and with persons with bilingual aphasia.

Research paper thumbnail of Acquired dysarthria within the context of the four-level framework of speech sensorimotor control

The South African journal of communication disorders. Die Suid-Afrikaanse tydskrif vir Kommunikasieafwykings, 2007

The Four-Level Framework of speech sensorimotor control (Van der Merwe, 1997) complicates the tra... more The Four-Level Framework of speech sensorimotor control (Van der Merwe, 1997) complicates the traditional view of dysarthria as a purely motor execution disorder. According to this framework, hypokinetic, hyperkinetic and ataxic dysarthria are programming-execution dysarthrias, while flaccid dysarthria is the only execution dysarthria. This preliminary study aimed to differentiate programming-execution dysarthria from execution dysarthria by examining variability of the temporal control of speech. Six participants and five control participants repeated 15 stimulus words ten times. Voice onset time, vowel duration, vowel steady state duration and vowel formant transition duration were measured acoustically. The coefficient of variation of the temporal parameters, and the correlation coefficient between the durational parameters, were calculated and analysed using descriptive statistics. The coefficient of variation revealed that the speakers with dysarthria were more variable than th...

Research paper thumbnail of Voice onset time of Afrikaans speaking children aged four to seven years

Southern African Linguistics and Applied Language Studies, 2002

ABSTRACT The scarcity of developmental voice onset time (VOT) data for pre-school children of dif... more ABSTRACT The scarcity of developmental voice onset time (VOT) data for pre-school children of different languages, limits deductions regarding the influence of linguistic and age factors on VOT. Expanded developmental VOT-data are of diagnostic value in comparing normal and disordered speech and language in various populations. The purpose of this study was to obtain normative, acoustic information regarding the nature of VOT of voiced and voiceless Afrikaans stops in ten children, ranging in age from 4.0-7.0 years. VOT-measurements were made from wide-band spectrograms, using the Kay digital signal processing sonagraph, model 5500. A multi-subject case study design was used and results are described both qualitatively and quantitatively. Individual mean VOT's for voiced stop contexts ranged from -97-+12ms. Four-year-olds displayed voicing lead in 27% of their mean VOT-values, five-year-olds 4% and six-year-olds 80%. Individual mean VOT-values for voiceless stop contexts ranged from +11-+37ms with very similar performance across age groups. All age groups showed overlapping VOT-values for voiced and voiceless stops (i.e. in the short lag voicing category). Results indicated possible differences between the developmental patterns of VOT in Afrikaans and English.

Research paper thumbnail of The effect of otitis media on articulation in children with cerebral palsy

International Journal of Rehabilitation Research, 1988

Research paper thumbnail of Temporal parameters of speech production in bilingual speakers with apraxic or phonemic paraphasic errors

Research paper thumbnail of Vocal effectiveness of speech-language pathology students: Before and after voice use during service delivery

Background: As a professional voice user, it is imperative that a speech-language pathologist’s (... more Background: As a professional voice user, it is imperative that a speech-language pathologist’s (SLP) vocal effectiveness remain consistent throughout the day. Many factors may contribute to reduced vocal effectiveness, including prolonged voice use, vocally abusive behaviours, poor vocal hygiene and environmental factors.
Objectives: To determine the effect of service delivery on the perceptual and acoustic features of voice.
Method: A quasi-experimental., pre-test–post-test research design was used. Participants included third- and final-year speech-language pathology students at the University of Pretoria (South Africa). Voice parameters were evaluated in a pre-test measurement, after which the participants provided two consecutive hours of therapy. A post-test measurement was then completed. Data analysis consisted of an instrumental analysis in which the multidimensional voice programme (MDVP) and the voice range profile (VRP) were used to measure vocal parameters and then calculate the dysphonia severity index (DSI). The GRBASI scale was used to conduct a perceptual analysis of voice quality. Data were processed using descriptive statistics to determine change in each measured parameter after service delivery.
Results: A change of clinical significance was observed in the acoustic and perceptual parameters of voice.
Conclusion: Guidelines for SLPs in order to maintain optimal vocal effectiveness were suggested.

Research paper thumbnail of Idiosyncratic sound systems of the South African Bantu languages: Research and clinical implications for speech-language pathologists and audiologists

The South African journal of communication disorders = Die Suid-Afrikaanse tydskrif vir Kommunikasieafwykings, 2014

The objective of this article is to create awareness amongst speech-language pathologists and aud... more The objective of this article is to create awareness amongst speech-language pathologists and audiologists in South Africa regarding the difference between the sound systems of Germanic languages and the sound systems of South African Bantu languages. A brief overview of the sound systems of two Bantu languages, namely isiZulu and Setswana, is provided. These two languages are representative of the Nguni language group and the Sotho group respectively.Consideration is given to the notion of language-specific symptoms of speech, language and hearing disorders in addition to universal symptoms. The possible impact of speech production, language and hearing disorders on the ability to produce and perceive speech in these languages, and the challenges that this holds for research and clinical practice, are pointed out.

Research paper thumbnail of What can speech production errors tell us about cross-linguistic processing in bilingual aphasia? Evidence from four English/Afrikaans bilingual individuals with aphasia

South African Journal of Communication Disorders, 2015

The aim of this study is contribute to clinical practice of bilinguals around the globe, as well ... more The aim of this study is contribute to clinical practice of bilinguals around the globe, as well as to add to our understanding of bilingual aphasia processing, by analysing confrontation naming data from four Afrikaans/English bilingual individuals with acquired aphasia due to a left hemisphere stroke. This is a case series analysis of four Afrikaans/English bilingual aphasic individuals following a left cerebrovascular accident. Error analysis of confrontation naming data in both languages was performed. Research questions were directed toward the between language differences in lexical retrieval abilities, types of errors produced and degree of cognate overlap. Three of the four participants showed significantly higher naming accuracy in first acquired language (L1) relative to the second acquired language (L2) and the largest proportion of error type for those three participants in both L1 and L2 was omission. One of the four participants (linguistically balanced) showed no between language accuracy difference. Regarding cognate overlap, there was a trend for higher accuracy for higher cognate words (compared to low). This study showed that naming performance in these four individuals was reflective of their relative language proficiency and use patterns prior to their stroke. These findings are consistent with the hierarchical model, in normal bilingual speakers and with persons with bilingual aphasia.

Research paper thumbnail of Acquired dysarthria within the context of the four-level framework of speech sensorimotor control

The South African journal of communication disorders. Die Suid-Afrikaanse tydskrif vir Kommunikasieafwykings, 2007

The Four-Level Framework of speech sensorimotor control (Van der Merwe, 1997) complicates the tra... more The Four-Level Framework of speech sensorimotor control (Van der Merwe, 1997) complicates the traditional view of dysarthria as a purely motor execution disorder. According to this framework, hypokinetic, hyperkinetic and ataxic dysarthria are programming-execution dysarthrias, while flaccid dysarthria is the only execution dysarthria. This preliminary study aimed to differentiate programming-execution dysarthria from execution dysarthria by examining variability of the temporal control of speech. Six participants and five control participants repeated 15 stimulus words ten times. Voice onset time, vowel duration, vowel steady state duration and vowel formant transition duration were measured acoustically. The coefficient of variation of the temporal parameters, and the correlation coefficient between the durational parameters, were calculated and analysed using descriptive statistics. The coefficient of variation revealed that the speakers with dysarthria were more variable than th...

Research paper thumbnail of Voice onset time of Afrikaans speaking children aged four to seven years

Southern African Linguistics and Applied Language Studies, 2002

ABSTRACT The scarcity of developmental voice onset time (VOT) data for pre-school children of dif... more ABSTRACT The scarcity of developmental voice onset time (VOT) data for pre-school children of different languages, limits deductions regarding the influence of linguistic and age factors on VOT. Expanded developmental VOT-data are of diagnostic value in comparing normal and disordered speech and language in various populations. The purpose of this study was to obtain normative, acoustic information regarding the nature of VOT of voiced and voiceless Afrikaans stops in ten children, ranging in age from 4.0-7.0 years. VOT-measurements were made from wide-band spectrograms, using the Kay digital signal processing sonagraph, model 5500. A multi-subject case study design was used and results are described both qualitatively and quantitatively. Individual mean VOT's for voiced stop contexts ranged from -97-+12ms. Four-year-olds displayed voicing lead in 27% of their mean VOT-values, five-year-olds 4% and six-year-olds 80%. Individual mean VOT-values for voiceless stop contexts ranged from +11-+37ms with very similar performance across age groups. All age groups showed overlapping VOT-values for voiced and voiceless stops (i.e. in the short lag voicing category). Results indicated possible differences between the developmental patterns of VOT in Afrikaans and English.

Research paper thumbnail of The effect of otitis media on articulation in children with cerebral palsy

International Journal of Rehabilitation Research, 1988

Research paper thumbnail of Temporal parameters of speech production in bilingual speakers with apraxic or phonemic paraphasic errors

Research paper thumbnail of Vocal effectiveness of speech-language pathology students: Before and after voice use during service delivery

Background: As a professional voice user, it is imperative that a speech-language pathologist’s (... more Background: As a professional voice user, it is imperative that a speech-language pathologist’s (SLP) vocal effectiveness remain consistent throughout the day. Many factors may contribute to reduced vocal effectiveness, including prolonged voice use, vocally abusive behaviours, poor vocal hygiene and environmental factors.
Objectives: To determine the effect of service delivery on the perceptual and acoustic features of voice.
Method: A quasi-experimental., pre-test–post-test research design was used. Participants included third- and final-year speech-language pathology students at the University of Pretoria (South Africa). Voice parameters were evaluated in a pre-test measurement, after which the participants provided two consecutive hours of therapy. A post-test measurement was then completed. Data analysis consisted of an instrumental analysis in which the multidimensional voice programme (MDVP) and the voice range profile (VRP) were used to measure vocal parameters and then calculate the dysphonia severity index (DSI). The GRBASI scale was used to conduct a perceptual analysis of voice quality. Data were processed using descriptive statistics to determine change in each measured parameter after service delivery.
Results: A change of clinical significance was observed in the acoustic and perceptual parameters of voice.
Conclusion: Guidelines for SLPs in order to maintain optimal vocal effectiveness were suggested.