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demonstrated significant differences in both gender, N
GL
-inte-
gral glottal width demonstrated a significant difference only
in males (
Tables 3
and
5
). There were no significant differences
in N
L
-amplitude mean or N
L
-mucosal wave magnitude mean.
Although the differences were not statistically significant,
N
L
-amplitude mean of VFA tended to be greater in males and
smaller in females, and N
L
-mucosal wave magnitude mean of
VFA tended to be smaller in both genders.
Multi-line digital kymography.
With MLK, patients with
VFA revealed significantly larger O
q
MLK
(
P
< 0.001;
Table 2
),
and this difference was significant in both genders (
Tables 3
and
5
).
Glottal area waveform.
The VFA group demonstrated
significantly smaller SI
GAW
(
P
< 0.001;
Table 2
). Although
the differences were not significant, the VFA group revealed
larger N
L
-maximal glottal area and N
L
-minimal glottal area
(
Table 2
).
Correlation study
Table 4
summarizes the correlation study between HSDI pa-
rameters and background data. Moderate correlations
(0.4 <
j
r
j
&
0.7) were found between mean flow rate and
O
q
MLK
, mean flow rate and N
L
-minimal glottal area, AA-F
0
and N
L
-amplitude mean, AA-F
0
and N
L
-minimal glottal area,
and O
q
SLK
and period perturbation quotient.
Table 6
summarizes the correlation study among the HSDI
parameters. A strong correlation (0.7 <
j
r
j
) was found between
N
L
-minimal glottal area and glottal area difference index.
Otherwise, moderate correlations (0.4 <
j
r
j
&
0.7) were found
in multiple pairs.
DISCUSSION
Videostroboscopy versus HSDI
The use of HSDI offered several advantages to the present study
over the previous studies in the literature. First, HSDI enabled
the evaluation of time parameters that cannot be assessed by
TABLE 4.
Correlation Coefficients (r) Between High-Speed Digital Image Parameters and Selected Aerodynamic/Acoustic Measures
Parameters
MPT
MFR AA-F
0
PPQ HNR
G
R
B
N
L
-amplitude mean
0.06
0.27
*
0.40
y
0.07
0.10
0.05
0.05
0.03
O
q
SLK
0.29
y
0.37
y
0.02
0.47
z
0.35
y
0.29
*
0.29
*
0.15
N
GL
-integral glottal width
0.20
0.39
y
0.30
*
0.19
0.15
0.18
0.18
0.02
O
q
MLK
0.34
y
0.49
z
0.16
0.34
y
0.31
*
0.26
*
0.26
*
0.13
O
q
GAW
0.28
*
0.28
*
0.14
0.29
*
0.04
0.24
*
0.24
*
0.23
SI
GAW
0.20
0.36
*
0.13
0.28
*
0.18
0.32
y
0.32
y
0.36
y
N
L
-minimal glottal area
0.22
0.53
z
0.43
z
0.12
0.10
0.20
0.20
0.21
Glottal area difference index
0.17
0.37
y
0.27
*
0.10
0.12
0.13
0.13
0.09
N
L
-glottal outlet
0.37
y
0.11
0.01
0.09
0.02
0.08
0.08
0.17
Abbreviations:
MPT, maximum phonation time; MFR, mean flow rate; AA-F0, fundamental frequency of acoustic analysis; PPQ, period perturbation quotient;
HNR, harmonics-to-noise ratio; G, grade; R, roughness; B, breathiness; NL-, normalized by vocal fold length; O
q
, open quotient; SLK, in single-line kymography;
N
GL
-, normalized by glottal cycle and vocal fold length; MLK, in multi-line kymography; GAW, in glottal area waveform; SI, speed index.
*
P
< 0.05.
y
P
< 0.01.
z
P
< 0.001.
TABLE 5.
Comparisons of High-Speed Digital Image Parameters Between the Control and VFA Groups in Males were summarized
Parameter (Units)
Control (N
¼
8)
VFA (N
¼
33)
t
Test
Laryngotopography
N
G
-lateral phase difference (%)
4.7 ± 4.4
5.9 ± 4.4
0.511
Single-line digital kymography
O
q
SLK
0.54 ± 0.12
0.75 ± 0.19
0.006
*
N
GL
-integral glottal width (%)
4.6 ± 2.3
7.8 ± 3.8
0.033
y
Multi-line digital kymography
O
q
MLK
0.42 ± 0.08
0.65 ± 0.20
0.003
*
Glottal area waveform
SI
GAW
0.16 ± 0.17
0.067 ± 0.166
0.002
*
Abbreviations:
VFA, vocal fold atrophy; N
G
-, normalized (by glottal cycle); Oq, open quotient; SLK, single-line kymography; N
GL
-, normalized by glottal cycle
and vocal fold length; MLK, multi-line kymography; SI, speed index; GAW, glottal area waveform.
Notes:
Values for control and VFA columns show ‘‘mean ± standard deviation,’’ and the
t
test column shows the
P
value of Student’s
t
test between male control
and male VFA groups.
*
P
< 0.01.
y
P
< 0.05.
Akihito Yamauchi,
et al
HSDI Analysis of VFA
94