PROCEEDINGS of the23rd International Congress on Acoustics
9 to 13 September 2019 in Aachen, Germany

Comparison of acoustic and laryngeal parameters between healthyand disordered subjects
Patrick SCHLEGEL1; Stefan KNIESBURGES1; Stephan DÜRR1; Michael DÖLLINGER1; AnneSCHÜTZENBERGER1
1

University Hospital Erlangen, Dept. of Otorhinolaryngology, Div. Phoniatrics & Pediatric Audiology

ABSTRACTIn voice research and clinics, various mathematical parameters are in use to describe different features of therecorded data. However, little is known about norm values of parameters and how they are affected bydifferent pathologies such as functional dysphonia.
Keywords: Phonation, parameters, functional dysphonia, high-speed video endoscopy

1. INTRODUCTION
In voice research, various parameters are in use [1], all of which are intended to describe different features ofthe phonation process to allow differentiation between groups of subjects. To determine the usefulness ofobjective parameters for the detection of functional dysphonia related disorders, we investigated data
recorded in a clinical environment applying many different objective parameters.

Figure 1 A) Recording of the vocal fold oscillations via a rigid endoscope being attached to a high-speed
camera and parallel audio recording using a clip microphone. B) Superior view of the vocal folds as seen
with the endoscope. C) Computed GAW: amount of pixel in the glottis over time.

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Patrick.schlegel@uk-erlangen.de2. METHODS
In total, 352 endoscopically recorded HSV videos with synchronously recorded audio were investigated.
Data collection and usage was approved by the ethic committee of the Medical School atFriedrich-Alexander-University Erlangen-Nürnberg (no. 290_13B). The videos were divided into fourgroups: females (162 healthy, 92 disordered) and males (67 healthy, 31 disordered) whereas all disorders
were functional dysphonia related. All subjects phonated the vowel /i/ at a comfortable pitch and loudness
level during examination. All videos were recorded by the clinically used Photron Fastcam MC2 with aspatial resolution of 512×256 pixels and a frame rate of 4000 fps. The synchronously recorded audio had asampling rate of 40000 Hz (in 19 cases for disordered females and in 2 cases for disordered males the audio
sampling rate was only 16000 Hz due to incorrectly set settings during recording). All videos included
exactly 1000 frames of recorded phonation.
The videos were recorded over three years and, in case of the “healthy” groups, are part of different
measurement series. Data from the disordered groups were not recorded as part of an organized series ofmeasurements. Instead, the data was collected over the years from various ENT clinic patients. Apart from
that, recording conditions stayed the same. For group-internal comparisons, subgroups were composed of thedifferent measurement series for the healthy group and from the different years for the disordered group.
In this work, we investigate the expressiveness of in total 59 glottal area waveform (GAW) parameters (fromwhich 33 were also calculated for the synchronously recorded audio signal).

Figure 2. Illustration of the segmentation process: 1. Selection of the region of interest 2. Selection of atime interval with constant phonation 3. Applying seed points and brightness thresholds to the center-frame
4. Reviewing and adjusting 5. Computing partial GAWs 6. Extraction of total and partial GAWs and audio.

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Table 1: Number of data sets for each subgroup. Each subgroup with at least 20 data sets is highlighted.
femalesmales

healthy

disorderedhealthy

disordered

Subgroup 12316222Subgroup 212401317Subgroup 330362912Subgroup 4

61-

--

Subgroup 522---Subgroup 6

14-

3-

total

1629267

31

Figure 3. The depicted statistical analysis workflow was performed for each parameter. *if only twosubgroups contained 20 values or more, intragroup comparison was done analogously to intergroupcomparison

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3. RESULTS AND DISCUSSION
Data analysis revealed that most parameters, for audio and GAW signals, did not show clear differences
between the healthy and the disordered groups. In fact, some parameters differed considerably between
different measurement series that were part of the healthy group. Out of 33 audio parameters only one
parameter showed a statistically significant difference between healthy and disordered groups but not also
between the different measurement series within the groups (intragroup comparisons). Also, this difference
may only be attributable to the deviating sampling frequency for some of the audio signals in the disorderedgroups. Out of 59 GAW parameters, 30 parameters were statistically significantly different between healthyand disordered groups for males, females or both, but not also statistically significantly different for
intragroup comparisons. The high proportion of statistically significantly different parameters for intragroupcomparisons on the one hand may be attributable to minor changes in the recording conditions as it may takeplace in a clinical environment (e.g. one of the medical doctors is diseased and a colleague has to take hisplace). On the other hand, often parameters are developed and tested on rather small sample sizes of audio
and video signals, recorded in a laboratory environment where sound-isolated rooms and optimal recording
conditions are available [2-4]. In some cases, the parameters are even tested exclusively on artificiallygenerated signals [5]. So the question arises if parameters tested by such means are still reliable if applied toclinical data.

4. CONCLUSIONSAs the results of this study imply, especially audio parameters seem to be not sufficiently robust to influenceson the measuring process, as they may take place in a clinical setting. Also, in general parameters thatchanged statistically significantly between the healthy and disordered groups but not within the groups only
showed limited deviations. However, it may be possible that a more complex, nonlinear multi-parametricbased approach could allow for a differentiation between healthy and disordered subjects.

ACKNOWLEDGEMENTS
This project is funded by the Deutsche Forschungsgemeinschaft (grant no. 323308998).

REFERENCES
1. Pedersen M, Jønsson A, Mahmood S, Agersted A. Which mathematical and physiologicalformulas are describing voice pathology: An overview. Journal of General Practice.
2016;4(253). doi:10.4172/2329-9126.1000253
2. Hillenbrand J, Cleveland R, Erickson RL. Acoustic correlates of breathy vocal quality. Journalof Speech and Hearing Research. 1994;37:769-778
3. Yumoto 5, Gould WJ, Baer T. Harmonics-to-nose ratio as an index of the degree of hoarseness.
Journal of the Acoustical Society of America. 1982;71:1544-1550
4. Qi Y, Hillman RE, Milstein C. The estimation of signal-to-noise ratio in continuous speech fordisordered voices. Journal of the Acoustical Society of America. 1999;105:2532-25355. Noise estimation in voice signals using short-term cepstral analysis. The Journal of the
Acoustical Society of America 2007;121(1679). doi: 10.1121/1.2427123

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Table 2: p-values for intra- and inter-group-comparisons of parameters, which changed significantly
between groups but not within a group.
Parameter nameSignal typep-value intra-groupp-value inter-groupfemales / males

females / males

Plateau Quotient

GAWT

0.690 / 0.817 *

0.000 / 0.038

Maximum-Area-Declination-RateGAWT- / 0.805- / 0.012

Peak-Closing-Velocity

GAWT

0.057 / -0.046 / -Amplitude-to-Length-Ratio

GAWT0.195 / -0.000 / -Harmonics Intensity

GAWT

0.336 / 0.397

0.000 / 0.010

Harmonic to noise ratio

GAWT

0.751 / -0.002 / -Normalized noise energy

GAWT

0.105 / -0.000 / -Signal to noise ratio v1

GAWT0.180 / -0.000 / -Signal to noise ratio v2

GAWT

0.575 / -0.022 / -Spectral flatness

GAWT

0.481 / 0.123

0.005 / 0.042

Mean Waveform matching coeff.

GAWT

0.198 / -0.046 / -Amplitude Variability Index

GAWT0.268 / -0.018 / -Energy Perturbation Quotient 5%

GAWT- / 0.142- / 0.014

Energy Perturbation Factor

GAWT- / 0.067- / 0.023

Time-Periodicity

GAWT- / 0.077- / 0.028

Mean Jitter

GAWT

0.117 / -0.041 / -Jitter Percent

GAWT- / 0.08- / 0.026

Jitter Factor

GAWT- / 0.077- / 0.023

Jitter Ratio

GAWT- / 0.08- / 0.026

Period Perturbation Quotient 3%

GAWT- / 0.071- / 0.033

Period Perturbation Quotient 5%

GAWT- / 0.118- / 0.022

Period Perturbation Factor

GAWT- / 0.08- / 0.025

Relative Average PerturbationB

GAWT- / 0.098- / 0.027

Relative Average PerturbationKGAWT- / 0.074- / 0.032

Period Variability Index

GAWT

0.609 / 0.128

0.005 / 0.005

Spatial Symmetry Index

GAWL / GAWR

- / 0.761- / 0.022

Amplitude Symmetry Index

GAWL / GAWR

0.756 / -0.007 / -Dynamic range Symmetry Index

GAWL / GAWR

0.987 / -0.012 / -Waveform symmetry index

GAWL / GAWR

- / 0.392- / 0.049

Phase Asymmetry

GAWL / GAWR

0.461 / -0.001 / -Harmonics Intensity

audio

0.436 / 0.790

0.000 / 0.018*The p-values from Kruskal-Wallis-test, Welch-ANOVA or ANOVA in case of multiple intra-groupcomparisons. For pairwise comparisons, the p-values of U-test, Tamhane-test or t-test are given (Dependingon whether the data was assumed to be normally distributed and if so with equal or unequal variances).

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