| 1. |
- Klionsky, Daniel J., et al.
(författare)
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Guidelines for the use and interpretation of assays for monitoring autophagy
- 2012
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Ingår i: Autophagy. - : Informa UK Limited. - 1554-8635 .- 1554-8627. ; 8:4, s. 445-544
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Forskningsöversikt (refereegranskat)abstract
- In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process vs. those that measure flux through the autophagy pathway (i.e., the complete process); thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from stimuli that result in increased autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field.
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| 2. |
- Nygren, M., et al.
(författare)
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Gender Differences in Children's Voice Use in a Day Care Environment
- 2012
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Ingår i: Journal of Voice. - : Elsevier BV. - 0892-1997 .- 1873-4588. ; 26:6
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Tidskriftsartikel (refereegranskat)abstract
- Background. The prevalence of dysphonia is higher in boys than in girls before puberty. This could be because of the differences in boys' and girls' voice use. Previous research on gender differences in prepubescent children's voice parameters has been contradictory. Most studies have focused on examining fundamental frequency. Objectives. The purpose of this study was to investigate voice use in boys and girls in a day care environment based on the voice parameters fundamental frequency (Hz), vocal intensity (dB SPL), and phonation time (%) and to ascertain whether there were any significant gender differences. Study Design. Prospective comparative design. Method. The study was conducted in a day care environment where 30 children (17 boys and 13 girls aged 4-5 years) participated. The participants' voices were measured continuously for 4 hours with a voice accumulator that registered fundamental frequency, vocal intensity level, phonation time, and background noise. Results. Mean (standard deviation) fundamental frequency was 310 (22) and 321 (16) Hz, vocal intensity was 93 (4) and 91 (3) dB SPL, and phonation time was 7.7 (2.0)% and 7.6 (2.5)% for boys and girls, respectively. No differences between genders were statistically significant. Conclusion. The finding of no statistically significant gender differences for measurements of voice parameters in a group of children aged 4-5 years in a day care environment is an important finding that contributes to increased knowledge about young boys' and girls' voice use.
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| 3. |
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| 4. |
- Karlsson, Fredrik, 1975-, et al.
(författare)
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Articulatory closure proficiency in Parkinson's disease patients following deep brain stimulation of the subthalamic nucleus and caudal zona incerta.
- 2014
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Ingår i: Journal of Speech, Language and Hearing Research. - 1092-4388 .- 1558-9102. ; 57, s. 1178-1190
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVEThe present study aimed at comparing the effects of deep brain stimulation (DBS) treatment of the subthalamic nucleus (STN) and the caudal zona incerta (cZi) on Parkinson's disease patients' proficiency in achieving oral closure and release during plosive production. METHODS Nineteen patients were evaluated preoperatively and 12 months after DBS surgery. Nine patients were implanted in the STN, seven bilaterally and two unilaterally (left). Ten were bilaterally implanted in the cZi. Postoperative examinations were made off and on stimulation. All patients received simultaneous L-dopa treatment in all conditions. For a series of plosives extracted from a reading passage, absolute and relative measures of duration of frication and amplitude of plosive release were compared between conditions within each treatment group. RESULTS Relative duration of frication increased in voiceless plosives in the on stimulation condition in cZi patients. Similar trends were observed across the data set. Duration of pre-release frication and the release peak prominence increased in voiceless plosives on stimulation for both groups. CONCLUSIONS The increased release prominence suggests that patients achieved a stronger closure gesture due to DBS, but that the increased energy available resulted in increased frication.
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| 5. |
- Karlsson, Fredrik, 1975-, et al.
(författare)
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Control of phonatory onset and offset in Parkinson patients following deep brain stimulation of the subthalamic nucleus and caudal Zona Incerta
- 2012
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Ingår i: Parkinsonism & Related Disorders. - : Elsevier. - 1353-8020 .- 1873-5126. ; 18:7, s. 824-827
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Tidskriftsartikel (refereegranskat)abstract
- Laryngeal hypokinesia is a common symptom in Parkinson’s disease (PD) that affects quality of life. Deep brain stimulation (DBS) is well recognized as a complementary method for treatment of motor symptoms in PD but the outcomes on patients’ control over phonatory alternation have yet not been clearly elucidated. The present study examined the effect of subthalamic nucleus STN-DBS (n=8, aged 51-72 yrs; median=63 yrs) and caudal Zona incerta cZi-DBS (n=8,aged 49-71 yrs; median=61 yrs) on control of onset and offset of phonation in connected speech. The patients were evaluated in a preoperatively (Med ON, 1.5 times the ordinary Levodopa dose) and 12 months postoperatively (Med ON, ordinary Levodopa dose). The results provided evidence of a progressive reduction in the ability to manifest alternations between voicing and voiceless states in a reading task. Mean proportion produced with inappropriate voicing increased from 47.6% to 55.3% and from 62.9% to 68.6% of the total duration for the two groups of patients between Pre-op and Post-op, Stim OFF evaluations. The medial and final parts of the fricative were more affected than the initial part, indicating an increased voicing lead into the following vowel. We propose that this reduction in phonatory control is be due to either progression of the disease, an effect of reduced Levodopa dosage or a microlesional effect. Patients’ proficiency in alternating between voiced and voiceless states in connected speech remained unaffected by both STN-DBS and cZi-DBS.
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| 6. |
- Karlsson, Fredrik, 1975-, et al.
(författare)
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Deep brain stimulation of caudal zona incerta and subthalamic nucleus in patients with Parkinson’s disease : effects on diadochokinetic rate
- 2011
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Ingår i: Parkinson's Disease. - : Hindawi Publishing Corporation. - 2090-8083 .- 2042-0080. ; 2011, s. 605607-
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Tidskriftsartikel (refereegranskat)abstract
- The hypokinetic dysarthria observed in Parkinson's disease (PD) affects the range, speed, and accuracy of articulatory gestures in patients, reducing the perceived quality of speech acoustic output in continuous speech. Deep brain stimulation (DBS) of the subthalamic nucleus (STN-DBS) and of the caudal zona incerta (cZi-DBS) are current surgical treatment options for PD. This study aimed at investigating the outcome of STN-DBS (7 patients) and cZi-DBS (7 patients) in two articulatory diadochokinesis tasks (AMR and SMR) using measurements of articulation rate and quality of the plosive consonants (using the percent measurable VOT metric). The results indicate that patients receiving STN-DBS increased in articulation rate in the Stim-ON condition in the AMR task only, with no effect on production quality. Patients receiving cZi-DBS decreased in articulation rate in the Stim-ON condition and further showed a reduction in production quality. The data therefore suggest that cZi-DBS is more detrimental for extended articulatory movements than STN-DBS.
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| 7. |
- Karlsson, Fredrik, 1975-, et al.
(författare)
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Pitch variability in patients with Parkinson’s disease : effects of deep brain stimulation of caudal zona incerta and subthalamic nucleus
- 2013
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Ingår i: Journal of Speech, Language and Hearing Research. - : American Speech-Language-Hearing Association. - 1092-4388 .- 1558-9102. ; 56:1, s. 150-158
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Tidskriftsartikel (refereegranskat)abstract
- Objective The purpose of the present study was to examine the effect of deep brain stimulation (DBS) of the subthalamic nucleus (STN) and the caudal zona incerta (cZi) pitch characteristics of con- nected speech in patients with Parkinson’s disease (PD).Methods Sixteen patients were evaluated preoperatively and 12 months after DBS surgery. Eight pa- tients were implanted in the STN (aged 51-72 yrs; xC=63 yrs). Six received bilateral implanta- tion and two unilateral (left) implantation. Eight patients were bilaterally implanted in the cZi (aged 49-71 yrs; xC=60.8 yrs). Preoperative assessments were made after an L-Dopa challenge (approximately 1.5 times the ordinary dose). All postoperative examinations were made off and on stimulation, with a clinically optimized dose of L-dopa. Measurements of pitch range and var- iability were obtained from each utterance in a recorded read speech passage.Results Pitch range and coefficient of variation showed an increase in patients under STN-DBS. Patients under cZi-DBS showed no significant effects of treatment on investigated pitch properties.Conclusions STN-DBS was shown to increase pitch variation and range. The results provided no evidence of cZi-DBS having a beneficial effect on PD patients’ pitch variability.
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| 8. |
- Kulneff, Linda, et al.
(författare)
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Deep brain stimulation : effects on swallowing function in Parkinson's disease
- 2013
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Ingår i: Acta Neurologica Scandinavica. - Hoboken : Wiley-Blackwell. - 0001-6314 .- 1600-0404. ; 127:5, s. 329-336
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Tidskriftsartikel (refereegranskat)abstract
- Objective: In patients with Parkinson’s disease (PD), deep brainstimulation of the subthalamic nucleus (STN DBS) is well recognizedin improving limb function, but the outcome on swallowing functionhas rarely been studied. The aim of this work was to evaluate theeffect of STN DBS on pharyngeal swallowing function in patientswith PD using self-estimation and fiberoptic endoscopic evaluation ofswallowing.Methods: Eleven patients (aged 41–72, median 61 years)were evaluated preoperatively and at 6 and 12 months after STN DBSsurgery. All patients were evaluated with self-estimation on a visualanalogue scale, and eight of them with a fiberoptic endoscopicexamination with a predefined swallowing protocol includingRosenbek’s Penetration-Aspiration Scale, Secretion Severity Scale,preswallow spillage, pharyngeal residue, and pharyngeal clearance.Results: The self-assessments of swallowing function revealed asubjective improvement with STN DBS stimulation, whereas the datafrom the swallowing protocol did not show any significant effect ofthe STN DBS treatment itself. The prevalence of aspiration was notaffected by the surgery.Conclusions: The results show thatswallowing function was not negatively affected by STN DBS and therisk of aspiration did not increase. Self-estimation of swallowingfunction showed a subjective improvement due to stimulation.
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| 9. |
- Louise, Johansson, et al.
(författare)
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Word-level intelligibility after caudal zona incerta stimulation for Parkinson’s disease
- 2014
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Ingår i: Acta Neurologica Scandinavica. - : Wiley-Blackwell. - 0001-6314 .- 1600-0404. ; 130:1, s. 27-33
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Tidskriftsartikel (refereegranskat)abstract
- Objectives – To investigate the effect of caudal zona incerta-deep brain stimulation (cZi-DBS) on word-level speech intelligibility in patients with Parkinson’s disease, under both an optimal listening condition and a simulated more naturalistic listening condition.Materials and methods – Spoken single words were extracted from read samples collected from 10 bilaterally implanted patients with PD pre- and post-cZi-DBS. Intelligibility was assessed through a transcription task performed by 32 naive listeners under two listening conditions: (i) with low-amplitude conversational speech added as background and (ii) with no added background noise. The listeners′ responses were scored in terms of agreement with the intended words.Results – Post-operatively, the total intelligibility score was significantly lower when cZi stimulation was switched on compared with off, for both listening conditions (with and without added background noise). Intelligibility was also significantly lower on stimulation compared with preoperative recordings, but only when assessed in the listening condition without background noise. The listening condition with added background noise resulted in significantly lower intelligibility scores compared with the no added noise condition for all stimulation conditions.Conclusions – The results of this study indicate that cZi-DBS in patients with PD can be detrimental to word-level speech intelligibility.
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| 10. |
- Lundgren, Sofie, et al.
(författare)
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Deep brain stimulation of caudal zona incerta and subthalamic nucleus in patients with Parkinson’s disease : effects on voice intensity
- 2011
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Ingår i: Parkinson's Disease. - : Hindawi Publishing Corporation. - 2090-8083 .- 2042-0080. ; 2011, s. 658956-
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Tidskriftsartikel (refereegranskat)abstract
- Deep brain stimulation of the subthalamic nucleus (STN-DBS) in patients with Parkinson’s disease (PD) affects speech in small, inconsistent ways. However, voice intensity generally increases. Recently the caudal zona inserta (cZi) has been investigated as an alternate target in DBS treatment of PD. The effects of cZi-DBS on voice intensity have not yet been investigated. The aim of this study was to compare the voice intensity effects of cZi-DBS and STN-DBS in PD patients. Voice intensity during reading and intensity decay during rapid syllable repetition were measured for eight STN-DBS and eight cZi-DBS patients in a pre-surgical baseline and then on- and off-stimulation 12 months after surgery. Voice intensity on-stimulation was larger than off-stimulation for the STN-DBS patients, but smaller for the cZi-DBS patients. There were no significant changes in intensity decay. The results suggest that cZi and STN are involved differently in neuromuscular control of the speech respiratory subsystem.
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| 11. |
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| 12. |
- Sundstedt, Stina, 1988-, et al.
(författare)
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Swallowing function in Parkinson’s patients following Zona Incerta deep brain stimulation
- 2012
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Ingår i: Acta Neurologica Scandinavica. - : John Wiley & Sons. - 0001-6314 .- 1600-0404. ; 126:5, s. 350-356
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Tidskriftsartikel (refereegranskat)abstract
- Objective The purpose of the present study was to examine if there was a negative effect of caudal Zona Incerta deep brain stimulation (cZI DBS) on pharyngeal swallowing function in Parkinson’s patients (PD). There are no former reports on swallowing and cZI DBS.Methods Eight patients (aged 49 to 71 years; median 62) were evaluated pre- and postoperatively, at six and 12 months after DBS surgery. Evaluation tools were Fiberoptic Endoscopic Evaluation of Swallowing examinations and patients’ self-assessments of the swallowing function including a visual analogue scale and quality of life related questions. The swallowing protocol included Rosenbeck’s Penetration-Aspiration Scale, Secretion Severity Scale and parameters for pre-swallow spillage, pharyngeal residue and pharyngeal clearance.Results There was no clear-cut effect of neurostimulation postoperatively at six and 12 months on any of the swallowing parameters except for pre-swallow spillage which was slightly worsened in the stimulation on condition 12m postoperatively. The answers to the self assessment questions did not vary significantly.Conclusions The effect of the stimulation on swallowing function varied among individuals but the overall outcome was that cZI DBS did not seem to have a negative influence on swallowing function in the eight patients studied.
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| 13. |
- Ballard, Kirrie J., et al.
(författare)
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Developmental Trajectory for Production of Prosody : Lexical Stress Contrastivity in Children Ages 3 to 7 Years and in Adults
- 2012
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Ingår i: Journal of Speech, Language and Hearing Research. - : American Speech-Language-Hearing Association. - 1092-4388 .- 1558-9102. ; 55:6, s. 1822-1835
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Accurate production of lexical stress within English polysyllabic words is critical for intelligibility and is affected in many speech-language disorders. However, models of speech production remain underspecified with regard to lexical stress. In this study, the authors report a large-scale acoustic investigation of lexical stress production in typically developing Australian English-speaking children ages 3-7 years (n = 73) compared with young adults (n = 24).Method: Participants named pictures of highly familiar strong-weak and weak-strong polysyllabic words. Of 388 productions, 325 met criteria for acoustic measurement. Relative vowel duration, peak intensity, and peak f(0) over the first two syllables were measured.Result: Lexical stress was marked consistently by duration and intensity but not f(0). Lexical stress on strong-weak words was adultlike by 3 years. All 3 measures showed significant differences between adults and children for weak-strong words still present at 7 years.Conclusion: Our findings suggest that protracted development of weak-strong stress production reflects physiological constraints on producing short articulatory durations and rising intensity contours. Findings validate treatment that is centered on strong-weak stress production for children >= 3 years with dysprosody. Although intervention for the production of weak-strong words may be initiated before age 7 years, reference to normative acoustic data is preferable to relying on perceptual judgments of accuracy.
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| 14. |
- Brunnegård, Karin, et al.
(författare)
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Comparison between perceptual assessments of nasality and nasalance scores
- 2012
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Ingår i: International journal of language and communication disorders. - : Wiley-Blackwell. - 1368-2822 .- 1460-6984. ; 47:5, s. 556-566
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Tidskriftsartikel (refereegranskat)abstract
- Background: There are different reports of the usefulness of the Nasometer™ as a complement to listening, often as correlation calculations between listening and nasalance measurements. Differences between findings have been attributed to listener experience and types of speech stimuli.Aims: To compare nasalance scores from the Nasometer with perceptual assessments, for the same and different Swedish speech stimuli, using three groups of listeners with differing levels of experience in judging speech nasality. Methods & Procedures: To compare nasalance scores and blinded listener ratings of randomized recordings using three groups of listeners and two groups of speakers. Speakers were either classified as having hypernasal speech or speech with typical speech resonance. Listeners were speech-language pathologists (SLPs) working predominantly with resonance disorders, other SLPs and untrained listeners.Outcomes & Results: Correlations (r(s) ) between hypernasality ratings and nasalance scores for each listener group and speech stimuli were calculated. For both groups of SLPs all correlations between perceptual ratings and nasalance scores were significant at p= 0.01. The correlations between the nasalance scores and ratings by listeners in the SLP groups were higher than those for the untrained listener group regardless of stimulus type. Post-hoc Mann-Whitney U-tests showed that the only difference that was significant was expert SLP group versus untrained listener group. Secondly, correlations between perceptual ratings and oral stimulus nasalance scores were higher when the perceptual ratings were based on spontaneous speech rather than on the oral stimulus. However, a Wilcoxon signed rank test showed that the difference was not significant. A third finding was that correlations between oral stimulus nasalance scores and perceptual scores were higher than those between mixed stimulus nasalance scores and perceptual scores. A Wilcoxon signed rank test showed that the difference was significant.Conclusions & Implications: The Nasometer might be useful for the SLP with limited experience in assessing resonance disorders in differentiating between hyper- and hyponasality. With listener reliability for ratings of hypernasality still being an issue, the use of a nasalance score as a complement to the perceptual evaluation will also aid the expert SLP. It will give an alternative way of quantifying speech resonance and might help in especially hard to judge cases.
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| 15. |
- Doorn, Jan van, et al.
(författare)
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Influence of speech task and utterance length on the measurement of pitch variability in the speech of Parkinson's disease patients after deep brain stimulation
- 2013
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Parkinson’s disease (PD) affects patients voice characteristics, reducing pitch variability compared to normal controls (1,2). Previous reports have shown an increase in pitch variability due to deep brain stimulation (DBS) of the Subthalamic nucleus (STN) (3). For patients stimulated in caudal zona incerta (cZi), the results indicate no effect on pitch variability in a read speech task{Karlsson:2012jr}.The present study aimed at investigating the effects of speech task (spontaneous or read speech) and the lenght of the utterance on overall measures of pitch variability observed in DBS-treated patients. Ten patients treated with STN-DBS and ten patients treated with cZi-DBS were included in this prospective study.Utterances produced sponatenously and produced during readings of a standard passage were compared in terms of treatment effects in pitch variability due to STN-DBS and cZi-DBS (Stim OFF and Stim ON recordings made 1,5 hour apart, all in Med ON) 6 and 12 months after operation. The results indicate that pitch variability is affected differently by STN-DBS and cZi-DBS depending on speech task and utterance length. In short utterances (<10 words), an increase in pitch variability is observed for both treatment groups and both speech tasks. For longer utterances, however, a more diverse effect of treatment and speech task is observed. The results therefore suggest that spech task and characteristics of thate utterance should be carefully considered when drawing conclusions on the overall effect of DBS on pitch variability.1. Jiménez-Jiménez FJ, Gamboa J, Nieto A, Guerrero J, Ortí-Pareja M, Molina JA, et al. Acoustic voice analysis in untreated patients with Parkinson's disease. Parkinsonism Relat. Disord. 1997 Apr;3(2):111–6. 2. Holmes RJ, Oates JM, Phyland DJ, Hughes AJ. Voice characteristics in the progression of Parkinson’s disease. International Journal of Language & Communication Disorders. 2000;35(3):407–18. 3. Dromey C, Kumar R, Lang AE, Lozano AM. An investigation of the effects of subthalamic nucleus stimulation on acoustic measures of voice. Mov. Disord. 2000;15(6):1132–8.
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| 16. |
- Eriksson, Erik J, 1978-, et al.
(författare)
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Detection of imitated voices : who are reliable earwitnesses?
- 2010
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Ingår i: The international journal of speech language and the law. - London : Equinox Publishing. - 1748-8885 .- 1748-8893. ; 17:1, s. 25-44
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Tidskriftsartikel (refereegranskat)abstract
- Factors affecting an individual's ability to identify people aurally are of forensic importance. This paper investigates how topic, dialect, gender, age, and hearing status affect detection of an imitated voice. Two imitations of the same person, but on different topics, were used as familiarization voices. One topic was associated with this person, and the other was not. Using discrimination sensitivity (d-prime) it was found that topic had a significant impact on d', as did age (but only when the topic was not associated with the imitated person). Dialect, gender and hearing status were not significant. The older group of listeners was less convinced by the imitations and in particular the one not associated with the person being imitated. These results imply that the validity of earwitness evidence is negatively affected by age and topic.
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| 17. |
- Karlsson, Fredrik, 1975-, et al.
(författare)
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Applying the Vowel Formant Dispersion (VFD) method to the study of reduced or alterered vowel productions
- 2012
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Formant centre frequencies are regularly used as acoustic measure of vowel quality because of the well established correlation between them and properties of vowel production(Fant, 1960). While it is recognised that it is important transform formant frequencies, as measured from the spectrogram, into relevant psychoacoustic scales when addressing issues of vowel perception, production studies are still largely based on the the raw, Hz-scaled, formant measurements. As a consequence, systematic studies of vowel articulation proficiency due to clinical conditions or effects of treatment are not easily afforded. A number of derived measures have been proposed to capture whole-system effect of vowel production. Previous research has primarily used the calculated total area of formants measured from either [a], [u], [i] and [æ] or only [a], [u] and [i] productions, joined together to form a quadrilateral or a triangle (Vowel space area, VSA)(Kent & Kim, 2003). In the reduced articulatory range of hypokinetic dysarthria, VSA is expected to be reduced by the dysarthria, and increased due to successful treatment the patient’s articulatory range. However, VSA has been proposed to be not powerful enough to capture effects on vowel articulation found specifically in patients with Parkinson’s disease (PD), and therefore not able to establish treatment effects.Two alternative measures have been proposed previously that are more focused towards specifically towards finding expansion and reductions in vowel spaces, the Vowel articulation index (VAI)(Roy, Nissen, Dromey, & Sapir, 2009) or Formant Centralization Ratio (FCR)(Sapir, Ramig, Spielman, & Fox, 2010). Both VAI and FCR has been shown to be able to establish significant reductions vowel articulation due to PD. Similar to VSA, however, the VAI and FCR measures do not given any detailed insight into the nature of the change in articulation. Further, all three measures reduces all obtained vowel formant measurements into a single metric, resulting in a substantial loss of statistical power and a considerable reduction in quality of intra-speaker models of articulatory proficiency. In response to the problematic properties of previous metrics, a revised view of formant frequencies more suitable for studies of changes in vowel articulation has recently been outlined, along with a new metric (Vowel Formant Dispersion, VFD). The VFD view of vowel formants are more closely connected to properties of vowel articulation and therefore affords more more detailed interpretations to be drawn concerning speakers’ production proficiency and offers increased reliability of within speaker estimates of this proficiency. This paper presents a detailed view of how VFD may applied to clinical populations where vowel production is affected by the condition (e.g. hypokinetic dysarthria) or where production should be affected (e.g. transexual patients or in successful treatment of dysarthric patients). It will be shown that most aspects of the study of vowel articulation proficiency will be significantly enhanced by the VFD method.
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| 18. |
- Karlsson, Fredrik, 1975-, et al.
(författare)
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Automatic acquisition of jitter and shimmer measurements across large sets of sustained vowel productions
- 2012
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Measurements of jitter and shimmer are frequently employed to quantify laryngeal control and stability during voice production in patients(1-3). Accurate estimates of jitter and shimmer may be obtained from acoustic recordings of sustained vowels produced by patients using computer software implementing algorithms for their extraction (e.g. Praat(4) or MDVP(5)). The jitter and shimmer algorithms do not, in themselves, exclude non-stable productions and are influenced by the inclusion of silence in the analysed intervals. As a consequence, reliable measurements of jitter and shimmer are made by manually opening each sound file and selecting an interval for the computations. The current paper proposes an alternative approach to afford a more efficient estimation of jitter and shimmer across a large set of sustained vowel recordings. Using information readily available in the acoustic signal and a combination of algorithms already available within the Praat program, a reliable method for automatic processing of only the sustained vowel in each recording of a large corpus is outlined. The method further affords the acquisition of multiple, repeatable, measurements of jitter and shimmer for sub-intervals of the vowel’s duration (applying more than one algorithm), which additionally provides information concerning the reliability of the jitter or shimmer estimates for a specific vowel production. Comparisons with manually obtained measurements are made for the purpose of validation of the segmentation method.
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| 19. |
- Karlsson, Fredrik, 1975-, et al.
(författare)
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Letter to the Editor
- 2012
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Ingår i: Journal of Voice. - : Elsevier. - 0892-1997 .- 1873-4588. ; 26:5
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 20. |
- Karlsson, Fredrik, 1975-, et al.
(författare)
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Treatment effects in voice onset time of plosives associated with deep brain stimulation of the subthalamic nucleus and the caudal zona incerta
- 2012
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Ingår i: Journal of medical speech-language pathology. - : Delmar Cengage Learning. - 1065-1438. ; 20:4, s. 65-69
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Tidskriftsartikel (refereegranskat)abstract
- The present study investigated the effect of deep brain stimulation (DBS) of the subthalamic nucleus (STN) and the caudal zona inserta (cZi) on motor control and coordination in plosives. A total of 2520 plosive productions, recorded during production of alternate motion rate and sequential motion rate tasks, were measured for voice onset time (VOT) when measurement was possible. Failed measurements were classified by the underlying cause. The resulting data were analyzed separately for each place of articulation of the intended plosive and compared with the articulatory properties of plosives not meeting the requirements for VOT measurement. The results showed no consistent overall stimulation effect in VOT regardless of place of articulatory closure. Furthermore, no overall pattern concerning the distribution of factors causing failures to measure VOT was observed. Instead, the results suggest a more complex interaction among place of articulation, speech task, and stimulation target in the determination of treatment effects of DBS in patients with Parkinson's disease (PD). The results further suggest that VOT may not provide a robust estimate of treatment effects in articulatory proficiency related to plosive production in patients with PD.
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| 21. |
- Karlsson, Fredrik, 1975-, et al.
(författare)
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Vowel formant dispersion as a measure of articulation proficiency
- 2012
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Ingår i: Journal of the Acoustical Society of America. - : Acoustical Society of America (ASA). - 0001-4966. ; 132:4, s. 2633-2641
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Tidskriftsartikel (refereegranskat)abstract
- The articulatory range of a speaker has previously been estimated by the shape formed by first and second formant measurements of produced vowels. In a majority of the currently available metrics, formant frequency measurements are reduced to a single estimate for a condition, which has adverse consequences for subsequent statistical testing. Other metrics provide estimates of size of vowel articulation changes only, and do not provide a method for studying the direction of the change. This paper proposes an alternative approach. Vowel formant frequencies are re-defined as vectors originating from a defined center point of the vowel space fixed to a basic three-vowel frame. The euclidian length of the vectors, the Vowel Formant Dispersion (VFD), can be compared across conditions for evidence of articulatory expansions or reductions across conditions or speaker groups. Further, the angle component of the vowel vectors allows for analyses of direction of the reduction or expansion. Based on the range of investigations afforded by the VFD metric, and simulation experiments that compare its statistical properties with those of other proposed metrics, it is argued that the VFD procedure offers an enhanced view of vowel articulation change over rival metrics.
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| 22. |
- Sandvik, Ulrika, 1978-, et al.
(författare)
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Thalamotomy for essential tremor : a very long-term follow-up
- 2012
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Ingår i: Open Neurosurgery Journal. - : Bentham Open. - 1876-5297. ; 5, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- Background: DBS (deep brain stimulation) is currently the golden standard in the surgical treatment of ET (essential tremor). Despite the benefits of DBS, there remain situations where lesional surgery may provide an alternative.Objective: To perform a very long-term retrospective evaluation of thalamotomies for ET.Methods: Nine patients who underwent thalamotomy for ET during 1972–1999 (follow-up period 20.8 ± 5.2 years) were assessed with regard to tremor scores, side effects, and quality of life, as well as lesion size and location.Results: All patients had tremor recurrence, although hand function remained slightly better on the treated side than on the non-treated side. Side effects that could be attributed to the procedure were frequent and did in some cases result in a disability for the patient. Quality of life was poorer in this group than in an age-adjusted healthy population. No correlation between lesion size, location, and long-term outcome could be established.Conclusions: In this study population the benefits of thalamotomies were limited, while complications were frequent.
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