The goal of this study was to analyse perceptually and acoustically the voices of patients with Unilateral Vocal Fold Paralysis (UVFP) and compare them to the voices of normal subjects. These voices were analysed perceptually with the GRBAS scale and acoustically using the following parameters: mean fundamental frequency (
A neural dysfunction of the larynx leads to alterations in voice, respiration, and airway protection. Usually, Unilateral Vocal Fold Paralysis (UVFP) is related to a set of well-documented perceptive alterations such as weak voice, breathiness, roughness, diminished voice intensity, vocal effort, low voice efficiency, voice breaks, diplophonia, and air loss [
The aim of this study was to compare perceptually and acoustically the voices of subjects with UVFP and the voices of subjects representing normal quality. Measures related to the vocal tract configuration, namely, formant frequencies, were also analysed and correlated with alterations caused by vocal pathology.
This is a quantitative, descriptive, and cross-sectional study [
Each pathologic case was individually matched to five subjects of the control group in order to increase the power of statistical tests [
Four (4) subjects with UVFP were male (23.5%) and 13 subjects were female (76.5%). The youngest patient was 30 years old and the oldest 72. The mean age for the pathologic group was 56.7 years with a standard-deviation of 12.7 years. Nine (9) patients had left UVFP (52.9%) and 8 right UVFP (47.1%). In the control group 20 subjects were male (23.5%) and 65 were female (76.5%). The mean age of the control group was 56.1 years and the standard-deviation was 12.7 years.
The voice recordings were made in a clinical setting using
Values of the autocorrelation method used in
Parameter | Value |
---|---|
Maximum number of candidates | 15 |
Silence threshold | 0.03 |
Voicing threshold | 0.45 |
Octave cost | 0.15 |
Octave-jump cost | 0.35 |
Voiced/unvoiced cost | 0.14 |
From the “voice report”
Each voice was also perceptually assessed using the GRBAS scale [
For the statistical analysis
All of the procedures had the acceptance of the Ethical Commission of the Hospital de Santo António and Hospital de São João. An authorisation from the National Commission for Data Protection was also obtained.
The consistency between the five judges that assessed the pathologic voices was analysed using Kendall’s
Interrater consistency—Kendall’s
Scale parameter |
|
|
---|---|---|
G | 0.263 | 0.001 |
R | 0.160 | 0.033 |
B | 0.381 | <0.001 |
A | 0.344 | <0.001 |
S | 0.438 | <0.001 |
G: Grade; R: Rough; B: Breathy; A: Asthenic; S: Strained;
The results of the perceptive assessment of the voices of the normal and UVFP subjects were analysed using the Mann-Whitney
Comparison of the results of GRBAS scale between UVFP and normal voice subjects.
UVFP | Normal |
|
|
|||
---|---|---|---|---|---|---|
|
Mean ± SD |
|
Mean ± SD | |||
G | 17 | 2.06 ± 0.827 | 85 | 0 | 0 | <0.001 |
R | 17 | 1.94 ± 0.899 | 85 | 0 | 0 | <0.001 |
B | 17 | 1.71 ± 0.772 | 85 | 0 | 0 | <0.001 |
A | 17 | 1.24 ± 0.437 | 85 | 0 | 0 | <0.001 |
S | 17 | 0.94 ± 0.556 | 85 | 0 | 25.5 | <0.001 |
UVFP: Unilateral Vocal Fold Paralysis; G: Grade; R: Rough; B: Breathy; A: Asthenic; S: Strained;
Comparison between mean scores of the GRBAS scale for normal and UVFP subjects.
One of the major alterations caused by UVFP is the incomplete glottal closure that originates excess air during phonation that creates a breathy voice (parameter B is altered) [
Although perceptive assessment is the most used technique for vocal assessment, it is a subjective process that leads to some variability issues [
Comparison of jitter, shimmer, and HNR between normal and UVFP subjects.
UVFP | Normal |
|
|
|||
---|---|---|---|---|---|---|
|
Mean ± SD |
|
Mean ± SD | |||
Jitter ppq5 (%) | 17 | 1.06 ± 1.02 | 85 | 0.26 ± 0.18 |
|
<0.001 |
Shimmer apq11 (%) | 17 | 10.16 ± 3.34 | 85 | 7.14 ± 3.22 |
|
0.001 |
HNR (dB) | 17 | 10.11 ± 4.94 | 85 | 14.75 ± 4.46 |
|
<0.001 |
UVFP: Unilateral Vocal Fold Paralysis; SD: standard deviation;
Jitter (%) values for UVFP and normal subjects.
Shimmer (%) values for UVFP and normal subjects.
HNR (dB) values for UVFP and normal subjects.
The parameters presented in Tables
Fundamental frequency (
♀ | UVFP | Normal |
|
|
||
---|---|---|---|---|---|---|
|
Mean ± SD |
|
Mean ± SD | |||
|
13 | 218.38 ± 72.36 | 65 | 195.36 ± 33.02 |
|
0.335 |
SD |
13 | 6.65 ± 12.28 | 65 | 2.62 ± 2.15 |
|
0.018 |
|
13 | 826.16 ± 171.73 | 65 | 819.03 ± 164.75 |
|
0.495 |
SD |
13 | 117.18 ± 99.91 | 65 | 71.28 ± 53.54 |
|
0.116 |
|
13 | 1522.69 ± 96.00 | 65 | 1453.51 ± 139.20 |
|
0.059 |
SD |
13 | 156.31 ± 146.20 | 65 | 62.26 ± 48.67 |
|
0.002 |
UVFP: Unilateral Vocal Fold Paralysis;
Fundamental frequency (
♂ | UVFP | Normal |
|
|
||
---|---|---|---|---|---|---|
|
Mean ± SD |
|
Mean ± SD | |||
|
4 | 121.43 ± 12.70 | 20 | 128.27 ± 23.85 |
|
0.485 |
SD |
4 | 3.41 ± 1.25 | 20 | 1.36 ± 0.58 |
|
<0.001 |
|
4 | 821.48 ± 331.80 | 20 | 677.33 ± 84.95 |
|
0.043 |
SD |
4 | 191.91 ± 105.62 | 20 | 30.58 ± 18.84 |
|
<0.001 |
|
4 | 1629.09 ± 474.06 | 20 | 1282.95 ± 104.35 |
|
0.011 |
SD |
4 | 263.68 ± 144.45 | 20 | 36.89 ± 27.53 |
|
0.001 |
UVFP: Unilateral Vocal Fold Paralysis;
The standard-deviation of
SD of
SD of
The vocal tract configuration interacts with VF oscillation; that is, vocal tract configuration constrains VF functioning during phonation [
Regarding
The second formant (
As for the SD of the frequency of
SD of
SD of
Overall results related to the vocal tract configuration (
It should be noted that the overall results obtained for females distance themselves from what was initially expected. These differences between genders may be due to a greater technical difficulty in analysing female voices [
In this study various ways of assessing the UVFP voice were combined. Since vocal therapy is one of the first noninvasive treatment options with potential to help the client to reacquire a functional voice, it is fundamental to know in detail the alterations created by the pathology at VF and vocal tract level to better guide the treatment. Perceptual differences between normal and UVFP voices were found. The perceptual parameters that better characterised this data of UVFP subjects were Rough (R) and Breathy (B), but altered values of Asthenic (A) and Strained (S) were also found. As far as acoustic parameters are concerned there were no differences in
The authors declare that there is no conflict of interests regarding the publication of this paper.
The authors would like to thank the Otorhinolaryngology Team from Hospital de Santo António and Hospital de São João. This work was partially funded by National Funds through FCT (Foundation for Science and Technology), in the context of the projects UID/CEC/00127/2013 and Incentivo/EEI/UI0127/2014. The Advanced Voice Function Assessment Databases (AVFAD) project is supported by the School of Health Sciences (ESSUA), University of Aveiro, Portugal.