Browsing by Person "Hewlett, Nigel"

Now showing 1 - 20 of 22

A quantitative and qualitative evaluation of an automatic occlusion device for tracheoesophageal speech: The Provox Freehands HME.
(Taylor & Francis, 2006-04) Hamad, Rachel; Hewlett, Nigel; Scanlon, Emer
This study aimed to evaluate a new automatic tracheostoma valve: the Provox FreeHands HME (manufactured by Atos Medical AB, Sweden). Data from four laryngectomee participants using automatic and also manual occlusion were subjected to acoustic and perceptual analysis. The main results were a significant decrease, from the manual to automatic occlusion condition, in maximum phonation time, mean intensity of read speech and percentage pause time. There was an increase in random noise in the speech signal and a significant increase in extraneous noise caused by the device. Perceptual analysis revealed no clear functional impact of these differences. Data from a questionnaire and diary suggested the main advantage of automatic occlusion was the freedom to speak while performing manual tasks. The principal disadvantage appeared to be a decrease in baseplate seal duration. The results suggest that, for some clients, the FreeHands valve is a useful option for use alongside manual occlusion.
An introduction to the science of phonetics.
(Lawrence Erlbaum Associates, 2006) Hewlett, Nigel; Beck, Janet M.
An ultrasound study of lingual coarticulation in /sV/ syllables produced by adults and typically developing children
(Cambridge University Press, 2012-08-02) Zharkova, Natalia; Hewlett, Nigel; Hardcastle, William J.; Economic and Social Research Council
According to the Degree of Articulatory Constraint model of lingual coarticulation, the consonant /s/ has some scope for tongue adaptation to neighbouring vowels, since the tongue dorsum is not directly involved in constriction formation for this consonant. The present study aimed to establish whether the tongue shape for /s/ in consonant-vowel syllables was influenced by the nature of the following vowel, in Scottish-English-speaking children and adults. Ultrasound tongue imaging was used to establish the presence or otherwise of a vowel effect at the consonant midpoint, by measuring differences between the consonant tongue contours in different vowel environments. In adults, the vowel pairs /a/-/i/, /a/-/u/ and /i/-/u/ exerted significant coarticulatory effects on /s/. In children, no significant effects on /s/ were observed. Greater within-speaker variability in lingual articulation was found in children than in adults. The reduced ability of children to anticipate the tongue configuration of a following vowel whilst simultaneously implementing an initial /s/ sound could be explained by lesser differential control of tip/blade and tongue body.
An ultrasound study of lingual coarticulation in children and adults
(2008-12) Zharkova, Natalia; Hewlett, Nigel; Hardcastle, William J.
There have been a number of studies which compared coarticulatory patterns in children and adults, but these studies have produced conflicting results, particularly with respect to anticipatory lingual coarticulation. This study used articulatory measures derived from ultrasound imaging, in order to establish any differences between child and adult coarticulatory patterns, and to quantify the degree of variability in children's and adults' productions. The participants were four adults and four normally developing children aged 6 to 9 years, all speakers of Standard Scottish English. The data were the syllables /i/, /u/ and /a/, in the carrier phrase It's a -_ Pam- (ten repetitions). Synchronised ultrasound and acoustic data were recorded using the Queen Margaret University ultrasound system. Extent of consonantal coarticulation and within-speaker variation in child and adult productions were compared according to a new ultrasound-based measure of coarticulation. A significantly greater amount of anticipatory lingual coarticulation was found in children than in adults. Much within-group variability was observed, in both age groups. Within-speaker variability was significantly greater in children than in adults. These results are in agreement with some previous studies. Possible reasons are discussed for some of the contradictions in the literature on child and adult coarticulation.
An ultrasound study of lingual coarticulation in children and adults: Full Research Report ESRC End of Award Report, RES-000-22-2833
(ESRC, 2009) Zharkova, Natalia; Hewlett, Nigel; Hardcastle, William J.
The aims of this project were to establish how children's patterns of coarticulation differ from adults', and to attempt to explain the observed coarticulatory patterns, as well as the nature and the degree of variability found in children and adults.
Analysing coarticulation in Scottish English children and adults : an ultrasound study
(Canadian Acoustical Association, 2008) Zharkova, Natalia; Hewlett, Nigel; Hardcastle, William J.
One of the gaps in our knowledge about developmental paths taken by children to adult-like motor control of speech concerns the development of coarticulation.
Children's perception of direct and indirect reported speech
(2003) Hewlett, Nigel; Kelsey, Cherry; Lickley, Robin
This study investigated the abilities of adults and children to distinguish direct reported speech from indirect reported speech in sentences read aloud by a native English speaker. The adults were highly successful, the older children less so and the younger children were relatively unsuccessful. Indirect reported speech appeared to be the default category for the children. Potential prosodic cues were identified and measured from waveforms and pitch contours of the stimulus sentences. Statistical analysis was applied with a view to ascertaining which (combination of) cues best predicted the listener responses. The results suggest that pitch movement and duration both provided important cues to distinguishing the sentence types. The analysis also revealed a learning effect by all groups.
Coarticulation as an indicator of speech motor control development in children: An ultrasound study
(2011-01) Zharkova, Natalia; Hewlett, Nigel; Hardcastle, William J.
There are still crucial gaps in our knowledge about developmental paths taken by children to adult-like speech motor control. Mature control of articulators during speaking is manifested in the appropriate extent of coarticulation (the articulatory overlap of speech sounds). This study compared lingual coarticulatory properties of child and adult speech, using ultrasound tongue imaging. The participants were speakers of Standard Scottish English, ten adults and ten children aged 6-9 years. Consonant-vowel syllables were presented in a carrier phrase. Distances between tongue curves were used to quantify coarticulation. In both adults and children, vowel pairs /a/-/i/ and /a/-/u/ significantly affected the consonant, and the vowel pair /i/-/u/ did not. Extent of coarticulation was significantly greater in the children than in the adults, providing support for the notion that children's speech production operates with larger units than adults'. More within-speaker variability was found in the children than in the adults. 2011 Human Kinetics, Inc.
Gradient change in the acquisition of phonology.
(Informa Healthcare, 2004) Hewlett, Nigel; Waters, Daphne
The prevailing view of phonological development is that changes in pronunciation are driven by phonological changes. This view (it is argued here) derives from the particular form of the data that has most often been used in studies of phonological development, namely broad phonetic transcriptions. Transcribing an earlier pronunciation with one phoneme symbol and a later pronunciation with a different symbol encourages the interpretation that the child has made a flip from one category to another. However, broad transcriptions may have misrepresented the facts of speech development. We review some auditory-based studies which have used a more fine-grained phonetic transcription and discuss the significance of findings on the development of long-lag plosives. We argue that gradient change is the typical fashion in which children's speech output development progresses; that it is therefore not appropriate to use rules of the sort that are employed for morphophonemic alternations in adult phonology to explain revisions over time in children's pronunciations; and that a child's speech output is not the best guide to their phonology.
Lingual Coarticulation in Preadolescents and Adults: An Ultrasound Study. ESRC End of Award Report, RES-000-22-4075
(ESRC, 2012) Zharkova, Natalia; Hewlett, Nigel; Lickley, Robin
When people combine sounds to make words, there is overlap in the tongue movements involved in articulating individual sounds, referred to as lingual coarticulation. For example, in adult speech, tongue positions at mid-consonant, in the words she- and shah-, differ because of the influence of the following vowel. The research team's earlier work showed that young children differed from adults in the extent of vowel-on-consonant coarticulation. In this project, for the first time, a quantitative analysis of the dynamics of tongue movements was performed. The project used high-speed ultrasound to measure lingual coarticulation in the syllables she-, shah-, sea- and 'Sah', comparing preadolescent children and adults, fifteen speakers in each age group. In both age groups and both consonants, the tongue position at mid-consonant was affected by the identity of the following vowel. There was no significant effect of age on the size of the vowel-related difference in tongue posture, nor on within-speaker variability in tongue placement. Age-related differences were observed in the onset of coarticulation. While in the adults, the vowel effect was present throughout the consonant for both consonants, in preadolescents the effect was apparent later into the first half of the consonant. The results of the study suggest a near-adult-like achievement in the development of lingual control by preadolescents, with respect to the coarticulation of fricative-vowel sequences. However age-related differences in timing may indicate that preadolescents have still to gain the extent of forward planning in speech production which is possible for a typical adult.
Measuring lingual coarticulation from midsagittal tongue contours: Description and example calculations using English /t/ and //
(2009-04) Zharkova, Natalia; Hewlett, Nigel
The purpose of this study was to test the feasibility of a protocol for measuring coarticulation using tongue surface outline data derived from ultrasound imaging. Ultrasound and acoustic data were collected from three speakers of Southern British English while they repeated a list of three sentences 15 times. Tongue surface outlines for the consonant /t/ in /a{script}ta{script}/ (in ...Ma tasked...) were compared with those for the /t/ in /iti/ (in ... Leigh teased...) and tongue surface outlines for the vowel /a{script}/ in /a{script}ka{script}/ (in ... Ma cast...) were compared with those in /a{script}ta{script}/. Nearest neighbour distance calculations were used for the comparison of tongue surface outlines. Mean distance in midsagittal tongue surface outline between tokens of the same phoneme across two different environments was taken as a measure of the phoneme's susceptibility to environmental influence. The calculations show that the tongue contour during /t/ adapts to the influence of the neighbouring vowels approximately three times more than the tongue contour during /a{script}/ adapts to the influence of the neighbouring consonants. The applicability of the measure proposed in this paper to future speech research using ultrasound and other articulatory techniques is discussed. 2008 Elsevier Ltd. All rights reserved.
Morphemes, Phonetics and Lexical Items: The Case of the Scottish Vowel Length Rule.
(International Congress of Phonetic Sciences, 1999) Scobbie, James M.; Turk, Alice; Hewlett, Nigel
We show that, in the Scottish Vowel Length Rule, the high vowels in the sequences /i#d/ and /##d/ are 68% longer than in the tautomorphemic /id/ and /ud/ sequences, while /ai#d/ is only 28% longer than /aid/. There is no quality difference associated with /i/ and /#/, but long and short /ai/ do differ in quality. Spectral analysis of F1 and F2 trajectories indicates that the prime difference in the vowels due to the SVLR appears to be the timing of formant movements, not the location of the targets in formant space. In the longer vowel of sighed, the rise towards a high front position starts at about 75ms-100ms into the vowel, and in the shorter vowel of side it is aligned nearer the start of the vowel. There are, moreover, genuine target differences which function as a marker of social class.
Perceptual Strategies in Phonological Disorder: Assessment, Remediation and Evaluation
(1998) Watson, Jocelynne; Hewlett, Nigel
Evidence is presented that immature perceptual strategies are a contributory factor to developmental phonological disorder. The findings endorse the current re-focusing of attention on the role of perception in disordered speech and language acquisition and also highlight the need for more precise assessment and remediation techniques. Technical developments working towards providing these are reviewed and implications for future clinical practice discussed.
Rural versus urban accent as an influence on the rate of speech
(Cambridge University Press, 1998-06) Hewlett, Nigel; Rendall, Monica
Speakers of rural accents have been said to speak more slowly than speakers of urban accents. However, there would appear to have been no previous empirical investigation of such a claim. In the study reported here, recordings were made of 12 Orkney English speakers and 12 Edinburgh English speakers, during a reading task and in conversation with the experimenter. Measurements, in syllables per second, were made of both the Speaking Rate and the Articulation Rate (i.e. the rate calculated after excision of pauses) of each speaker in reading mode and in conversation mode. Comparison of the results for the two groups revealed no tendency for the urban (Edinburgh) speakers to speak faster than the rural (Orkney) speakers. The claim that rural speakers speak more slowly than urban speakers therefore still awaits empirical support. Some discussion is offered concerning the possible relationships among speech tempo, lifestyle and accent.
Spatial and temporal lingual coarticulation and motor control in preadolescents
(ASHA, 2014-04) Zharkova, Natalia; Hewlett, Nigel; Hardcastle, William J.; Lickley, Robin
Purpose: Coarticulation and lingual kinematics were compared in preadolescents and adults, in order to establish whether preadolescents had a greater degree of random variability in tongue posture and whether their patterns of lingual coarticulation differed from those of adults. Method: High-speed ultrasound tongue contour data synchronised with the acoustic signal were recorded from 15 children aged between 10 and 12 years old, and 15 adults. Tongue shape contours were analysed at nine normalised time-points during the fricative phase of schwa-fricative-/a/ and schwa-fricative-/i/ sequences with the consonants /s/ and /ʃ/. Results: There was no significant age-related difference in random variability. Where a significant vowel effect occurred, the amount of coarticulation was similar in the two groups. However, the onset of the coarticulatory effect on preadolescent /ʃ/ was significantly later than on preadolescent /s/, and also later than on adult /s/ and /ʃ/. Conclusions: Preadolescents have adult-like precision of tongue control and adult-like anticipatory lingual coarticulation with respect to spatial characteristics of tongue posture. However, there remains some immaturity in the motor programming of certain complex tongue movements.
Standard English in Edinburgh and Glasgow: the Scottish vowel length rule revealed.
(Arnold, 1999) Scobbie, James M.; Hewlett, Nigel; Turk, Alice E.
The gender imbalance among speech and language therapists and students
(Wiley-Blackwell, 2001-04) Boyd, Steven; Hewlett, Nigel
Speech and language therapy is still a predominantly female profession. This paper reports the numbers and percentages of males among the population of student speech and language therapists in the UK in 1999-2000. The numbers imply that there is no prospect of redressing the gender imbalance in the near future. Information was gathered by means of a questionnaire to male speech and language therapy students and male therapists on the reasons for their career choice and their occupation-related experiences concerning their gender. Most therapists reported advantages from their gender but a minority reported difficulties arising from being a man in the speech and language therapy profession. The issue of working alone with children is identified as being in urgent need of resolution.
The Influence of Phonemic Awareness Development on Acoustic Cue Weighting Strategies in Children's Speech Perception
(2003-10) Mayo, Catherine; Scobbie, James M.; Hewlett, Nigel; Waters, Daphne
In speech perception, children give particular patterns of weight to different acoustic cues (their cue weighting). These patterns appear to change with increased linguistic experience. Previous speech perception research has found a positive correlation between more analytical cue weighting strategies and the ability to consciously think about and manipulate segment-sized units (phonemic awareness). That research did not, however, aim to address whether the relation is in any way causal or, if so, then in which direction possible causality might move. Causality in this relation could move in 1 of 2 ways: Either phonemic awareness development could impact on cue weighting strategies or changes in cue weighting could allow for the later development of phonemic awareness. The aim of this study was to follow the development of these 2 processes longitudinally to determine which of the above 2 possibilities was more likely. Five-year-old children were tested 3 times in 7 months on their cue weighting strategies for a /so/-/So/ contrast, in which the 2 cues manipulated were the frequency of fricative spectrum and the frequency of vowel-onset formant transitions. The children were also tested at the same time on their phoneme segmentation and phoneme blending skills. Results showed that phonemic awareness skills tended to improve before cue weighting changed and that early phonemic awareness ability predicted later cue weighting strategies. These results suggest that the development of metaphonemic awareness may play some role in changes in cue weighting.
The Trough Effect: an ultrasound study.
(Karger, 2007-08) Vazquez-Alvarez, Yolanda; Hewlett, Nigel
Bilabial stops often show a lowering of the tongue in symmetrical VCV sequences. The causes of this phenomenon, sometimes called the 'trough effect', are unknown. However, it could have important implications for the study of timevarying aspects of speech events. Ultrasound is a non-invasive technique that has allowed us to image the shape of the tongue in real time and measure the actual tongue displacement that occurs in the C of a VCV sequence. Five repetitions of symmetrical V1CV2 sequences with the bilabial stops /b, p/ were obtained from 10 British English speakers. Results showed not only differences in the direction and degree of the tongue displacement but also differences in the tongue contour configuration between subjects. This study demonstrates the effectiveness of ultrasound as a technique in phonetic research, making possible the analysis of tongue surface movement for large amounts of data from multiple subjects.
Vowel Assessment for Systems of English (VASE)
(1999) Bates, Sally; Hewlett, Nigel; Kaighin, Sally; Sinclair, Alison; Sweet, Jane; Watson, Jocelynne
VASE is a single word picture naming task which has been especially designed to assess vowel production in children presenting with developmental phonological disorder. The full assessment comprises 53 line drawings plus a set of transcription sheets, realisation score sheets and vowel system profiles. The transcription, scoring and vowel system profile sheets are all photocopiable. The screening assessment consists of 10 line drawings (selected from those used in the full assessment) plus transcription and score sheets. The full assessment may be administered in its entirety, recommended in complex cases presenting with moderate-severe consonant and/or vowel difficulty, or selectively depending on the results of the screener. For example, if a child shows errored realisation on one or two vowels only, it is not necessary to further assess the full range of vowels across all contexts. Rather the clinician may select those pictures which will generate additional tokens of the problem vowels highlighted by the screener.