JCPSLP vol 14 no 3 2012

Table 3. Results of acoustic analyses with normative comparisons Measures P1 – M (Spastic) Comparison data

P2 – F (Ataxic)

Comparison data

P3 – M (Flaccid)

Comparison data

Vocal quality Sustained /a/ Average duration (sec) 1

14.2

25.9

12.76

21.3

9.53

25.9

Average f0 2

174.0

145.2 Range: 121.8–168.6

256.5

243.9 Range: 216.5–271.4

156.2

145.2 Range: 121.8–168.6

Standard deviation f0 2

1.2

1.3 Range: 0.7–2.0

11.4

2.7 Range: 0.6–4.8

2.4

1.3 Range: 0.7–2.0

Jitter (local) 2

0.54

≤ 1.04% ≤ 3.81%

0.55

≤ 1.04% ≤ 3.81%

0.64

≤ 1.04% ≤ 3.81%

Shimmer (local) 2

2.87

3.74

2.76

Harmonic-to-noise ratio 2

19.47 >20

19.38

>20

19.96 >20

Speech rate and prosody Alternating Motion Rate tasks 3 ‘pa’ repetition (syll/sec)

3.4

Range: 4.5–7.5

2.5

Range: 4.6–8.6

2.5

Range: 4.5–7.5

‘ta’ repetition (syll/sec)

3.3

Range: 4.4–8.2

2.3

Range: 4.3–8.5

2.5

Range: 4.4–8.2

‘ka’ repetition (syll/sec)

3.6

Range: 4.4–7.5

2.0

Range: 4.3–7.9

2.3

Range: 4.4–7.5

Sequential Motion Rate task 3 ‘pataka’ repetition (syll/sec) Connected speech (Grandfather) Speech rate (syll/sec) 4 Pairwise Variability Indices 5 duration

3.6

Range: 4.8–7.2

3.4

Range: 4.8–7.2

2.8

Range: 4.8 – 2.0

2.1

4.3 (± 0.5)

1.4

4.3 (± 0.5)

0.7

4.3 (± 0.5)

29.3**

46.6

25.8**

47.8

28.5**

58.4

f0

10.4

9.4

9.1

7.0

4.7**

7.3

dB

4.5

3.8

4.5

3.1

3.1**

5.6

Note: Underline = values outside normal range 1 Colton et al. (2006)

2 Norms from Multi-Dimensional Voice Program (MDVP; Kay PENTAX, Lincoln Park, USA): MDVP Jitt and Shim cut-off values are used, but are conservative here as the Jitter and Shimmer measures in PRAAT are less influenced by noise (http://www.fon.hum.uva.nl/praat/manual/Voice. html; Maryn et al., 2009) 3 Kent (1997) 4 Tauroza & Allison (1990) 5 Comparison data from matched controls; controls’ duration values are comparable to Low et al. (2000) for “reduced vowel set” sentences; **p<0.01 and *p<0.05 for Wilcoxin Matched Pairs tests between participant and matched control.

Participant 3 Vocal quality

threshold for pathological voice, and this was consistent with the absence of any perception of vocal roughness. The value for shimmer was close to the conservative threshold supporting the perception of loudness variations and vocal tremulousness. HNR was slightly below the recommended threshold, indicative of mild vocal hoarseness although this was not noted in the perceptual evaluation. Speech rate and prosody Performance on AMR and SMR tasks was characteristic of ataxic dysarthria with fewer syllables per second and the perception of slowed speech rate and disrupted rhythm. Speech rate was considerably reduced in the reading task, compared to healthy adults. The predominant prosodic features perceived in P2’s speech were equal and excess stress, irregular pitch breaks, and higher than normal loudness variation. This participant showed the lowest PVI_Dur value, significantly lower than the control, which is consistent with equal and excess stress. PVI_ f0 and PVI_dB were slightly elevated, but not significantly different to the control speaker.

Duration of sustained ah was considerably reduced, suggestive of reduced respiratory-phonatory control and more rapid loss of air with breathiness. Average f0 , standard deviation of f0 , jitter and shimmer were within the normal range on ah production. HNR was reduced relative to the threshold, suggestive of hoarseness, although the participant was perceived to have a breathy rather than hoarse quality. Speech rate and prosody The perception of slowed speech rate was upheld with slowed repetition rates on AMR and SMR tasks and particularly for connected speech, compared to normal. P3’s PVI_Dur was significantly reduced compared to the control participant, suggesting equalisation of stress in connected speech, despite this not being reported perceptually. However, the participant was perceived to have vowel and consonant prolongations, which may

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JCPSLP Volume 14, Number 3 2012

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