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An Investigation of the Effect of Multiple Productions on the Single Word Production of People with Acquired Speech Sound Production Difficulties: An Analysis.

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Presentation on theme: "An Investigation of the Effect of Multiple Productions on the Single Word Production of People with Acquired Speech Sound Production Difficulties: An Analysis."— Presentation transcript:

1 An Investigation of the Effect of Multiple Productions on the Single Word Production of People with Acquired Speech Sound Production Difficulties: An Analysis of 2 Cases Lynn Li Lim 1,2, Karen Croot 1,2,3, Sallyanne Palethorpe 1,2, Max Coltheart 1,2 1. Macquarie Centre for Cognitive Science (MACCS), Macquarie University 2. Speech Hearing and Language Research Centre (SHLRC), Macquarie University 3. School of Psychology, The University of Sydney

2 Acoustic Analysis Speech disorders may share similar symptoms of impaired speech production To determine the speech disorder associated with the symptom  examine speech segment productions acoustically Gives more concrete information on speech qualities attributed to phonological & articulatory deficits More reliable than impressionistic phonetic transcription (Haley et al, 2001)

3 Acoustic Speech Analysis Most common acoustic investigations are on contrastive features to determine if speech segment errors are: Phonemic – substitution of one phoneme for another Phonetic – impaired articulation of a speech sound (Baum et al, 1990; Tuller, 1984)

4 Variability in Speech Production Unimpaired speech production can be somewhat variable (Auzou et al, 2000) Acoustic studies usually rely on multiple productions of speech tokens to overcome this variability People with speech disorders are far more variable in their productions than controls (Ryalls, 1986) But disordered speech analyses have not addressed the issue of possible effects of multiple productions And their results have been inconsistent

5 Multiple Production Not known if eliciting multiple word productions from these people affects their speech sound production difficulties H 1 : Fatigue –deterioration of speech production H 2 : Practice –improvement in speech production H 0 : No effect on speech production

6 Previous Studies Some examples for Vowel Duration Study: Ryalls (1986)Tuller (1984)Williams & Seaver (1986) Speakers5 N/FL 7 FL 5 N/FL 5 FL 7 N/FL 14 FL Repetitions per word 5161 Mean Durations N/FL & FL > CTRL 2 N/FL > Others VariabilityN/FL > FL & CTRLN/FL & FL > CTRL (Only some) N/FL & FL < CTRL

7 Multiple Production Implication: If there are effects, then method of eliciting speech tokens may confound the investigation of the nature of the disorder

8 Other Features of Speech Production Previous acoustic studies address question of whether speakers produce phonemic or phonetic errors Other information about speech production difficulties that are non-contrastive in nature These are not usually reported in most acoustic studies

9 Research Questions Q1: Does multiple repetition of target words affect phonetic parameters of the speech of people with impaired speech sound production? Q2: Are there other phonetic parameters in the speech of these individuals that might be indicative of the nature of the disorder but not usually reported?

10 Speakers AR 63 y.o., male progressive aphasia with other mild cognitive deficits 2.5 years after presentation impaired syntax & phoneme discrimination semantic abilities just below control range moderate hearing loss (35-50 dB loss at 4kHz, 55-70 dB loss at 6 kHz)

11 Speakers HO 62 y.o., male left middle cerebral artery infarct early 1996 unimpaired visuo-perceptual processing of pictures & words semantic abilities just below control range impaired receptive phonological processing moderate hearing loss (45-55 dB loss at & above 4 kHz)

12 Material Experiment 1Experiment 2 Words1512 Repetitions (per session) 615 Sessions 5 5 * Words were presented in pseudo-random order among fillers TaskReading Words used in current study bed, big, dark, duck,pen, pig, pick, saw, sea buck, bug puck, pad, pat Speaker(s)AR, HOHO

13 Recordings digitised at 20,000 Hz Spectrograms hand-labelled & analysed using the EMU speech database system & the R statistical analysis software Acoustic dimensions analysed:  Burst Release Duration (BRDUR)  Vowel Duration (VDUR)  Fricative Spectral Moments (FSM)  First SM (SM1): average spectral frequency Acoustic Procedure

14 Q1: Statistical Analysis Repeated Measures ANOVA To investigate for any significant differences in the variance between sessions Sphericity: assumption that variance is equal between pairs of scores (Field, 2000, p.324)

15 Q1: Results - Error-bar Plots Example: Burst Release Duration of /d/ (AR) dark duck

16 Q1: Results - Error-bar Plots Example: Burst Release Duration of /p/ (HO)

17 Q1: Results - Error-bar Plots Example: 1st Spectral Moment of /s/ (HO) sawsea

18 Q1: Results - Error-bar Plots Example: Vowel Duration of / I / (AR)

19 Vowel duration / I / in “Big” (Speaker AR) Descriptive Statistics MeanStd. DeviationN SESSION1177.233325.694256 SESSION2187.533331.515826 SESSION3135.016720.129126 SESSION4133.680025.644296 SESSION5161.983321.518036 Mauchly's Test of Sphericity Within Subjects EffectMauchly's WApprox. Chi-SquaredfSig. Speaker AR (Big - VDUR).01314.9549.127 Tests of Within-Subjects Effects SourceSum of SquaresdfMean SquareFSig. Speaker AR (Big – VDUR)14230.61243557.6536.798.001 Error10466.87420523.344 Q1: Results - ANOVA

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21 Q1: Summary of Results ANOVA: significant differences between sessions for only some words Post-hoc: significant differences between session means were few and no pattern of increase/decrease in differences across sessions Results were similar for VDUR, BRDUR, Fricative SM1, the other words, both speakers Results were also similar in 2nd experiment

22 Q1: Summary of Results No change across sessions = no effect (practice/fatigue) of multiple productions Also, no. of repetitions in Exp 2 > Exp 1, yet no effect of increased repetition on speech production

23 Implication of Results method of eliciting multiple production may not confound investigation of nature of speech disorder but for treatment – practice of this type elicited in this study may not contribute to improvement in speech production

24 Q2: Other Speech Production Features Pre-voicing (HO) Pre-voicing Example: Bug Figure 1aFigure 1b

25 Q2: Other Speech Production Features Pre-voicing (HO) –voicing preceding release of word initial /b/ & /d/ Impaired laryngeal control – difficulty coordinating timing of stop release for voiced stops WordOccurrence Bed83% Big52% Buck95% Bug89% Dark52% Duck63%

26 Q2: Other Speech Production Features Schwa appended to final stop (HO) Example: Pad Schwa Figure 3

27 Q2: Other Speech Production Features Schwa appended to word-final stop (HO) –Voiced stops Indicative of careful speech production Or due to speech disorder Or due to hearing loss WordOccurrence /d/ in “Bed”93% /d/ in “Pad”44% /g/ in “Big”86% /g/ in “Bug”77% /g/ in “Pig”53%

28 No pattern in occurrence of these features over sessions Not an effect of multiple production May just be characteristic of disordered speech production Q2: Other Speech Production Features - Summary

29 Future Directions Word-final consonants (stops) Nasal consonants Co-articulation Analysis of the other speech production features Analysis of control data

30 Thank you for listening


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