Dysphonia Severity Index v.02.03 script
The Dysphonia Severity Index (i.e., DSI) has been developed by Wuyts et al. (2000). It is a well-established, objective and multivariable estimate of dysphonia severity. However, with measures strongly associated with vocal capacity, the DSI is assumed to indicate more adequately the restrictions in vocal functioning and may be applied as a more general measure of vocal function/performance and voice disorder (Awan & Ensllen, 2010; Maryn et al., 2017).
Because of the advantages of working with the program Praat and the fact that it is commonly used for both clinical and research purposes, Maryn et al. (2017) developed a procedure to administer a DSI-like protocol in Praat (DSI-beta or currently DSI v.02.03) and compared the outputs of this procedure with the DSI utilizing the original methods. Although not perfect, the correlation between the two methods was strong across three voice clinics. With the PHONANIUM script for determining the DSI v.02.03 in the program Praat, all relevant aspects regarding DSI can easily be obtained.
Author of the Dysphonia Severity Index v.02.03 script
Included in this download
- Access to tutorial video with concise theory and illustration(s) on how to determine and interpret the DSI
- Access to tutorial video with concise theory and illustration(s) on how to calibrate intensity level measurements
- Access to tutorial video with concise theory and illustration(s) on how to evaluate the quality of sound recordings
- Access to tutorial video on how to work with the Personal information – New file script
- Access to tutorial video on how to implement/install plug-ins in the program Praat
- This plug-in
Name of plug-in
Content of plug-in
- Dysphonia Severity Index v.02.03.praat: to determine several numerical data and graphs related to vocal IL with PHONANIUM’s script in the program Praat.
- setup.praat: to couple this script to a button in the dynamic menu of the program Praat.
- calibrationParameters.Table: a table in which previously and currently entered calibration data are stored. The last data set is used for calibration of the intensity levels measured in this script.
How to install this plug-in?
First, make sure to have downloaded and installed the program Praat (free available at www.praat.org) on your computer. Than download this plug-in.
Once downloaded, unzip the folder entitled plugin_PHONANIUM_DSI_v.02.03 and place it in the following directory (i.e., the preferences directory of the program Praat), depending on your computer operating system and the name of the user (for example ‘Emiel’):
- Windows (Vista or later): C:\Users\Emiel\Praat\.
- Mac OSX: /Users/Emiel/Library/Preferences/Praat Prefs/. (However, sometimes the Library folder is hidden on a Mac OSX. If this is the case, you first open Finder, select the Go menu, and then press the alt key ⌥. While pressing the alt key ⌥, the Library becomes available as an option in the Go menu and can then be clicked/opened.)
- Linux: /UserName/.praat-dir/.
What is DSI?
The DSI is one of the outcomes of a multicentric project of the Belgian Study Group on Voice Disorders. It is constructed on the basis of numerous data derived from 68 normophonic and 319 dysphonic subjects (Wuyts et al., 2000). The following variables were assessed in that project:
- anamnestic data: vocal abuse, allergy, chronic obstructive pulmonary disease, mental stress, nasal problems, and smoking;
- laryngeal stroboscopy;
- auditory-perceptual evaluation of voice signals according to the GRBAS-protocol;
- three acoustic measures from the Multi-Dimensional Voice Program (i.e., MDVP; Pentax Medical, Tokyo, Japan; formerly known as Kay Elemetrics and KayPentax): jitter percent, shimmer percent, and noise-to-harmonics ratio;
- seven phonetographical measures from the Voice Range Profile (i.e., VRP; Pentax Medical, Tokyo, Japan; formerly known as Kay Elemetrics and KayPentax): softest intensity, loudest intensity, intensity range, lowest fundamental frequency, highest fundamental frequency, fundamental frequency range in Hertz, and fundamental frequency range in semitones;
- three aerodynamic measures: maximum phonation time, vital capacity, and phonation quotient.
These data can be consulted in Wuyts et al. (1996). For the development of the DSI, Wuyts et al. (2000) applied a multivariate statistical procedure called ‘stepwise logistic regression’, with G (i.e., auditorily perceived overall dysphonia severity) as independent variable and the ten acoustic and three aerodynamic measures as dependent variables. Based on the unstandardized coefficients, and after posthoc linear rescaling the mean DSI of the severely dysphonic group to -5 and the mean DSI of the normophonic group to +5 (for reasons of practicality and easy interpretation), this procedure resulted in the following original formula:
DSI = 12.4 + (0.13 x maximum phonation time) + (0.0053 x highest fundamental frequency) – (0.26 x softest intensity) – (1.18 x jitter percent)
This DSI thus is a combination of four weighted variables to best discriminate between different dysphonia severity levels. The lower the DSI, the more severe the dysphonia. It is possible to find DSI scores outside the -5/+5 interval.
What is DSI v.02.03?
As found by Aichinger et al. (2012), variability in DSI between computer systems and programs, may arise from dissimilarities in pitch detection algorithm prior to determining jitter [as illustrated in e.g. Maryn et al. (2009)] or insufficiently calibrated intensity level measures (Maryn & Zarowski, 2015). It is thus crucial for the DSI to stick as much as possible to its original materials and methods. This however corresponds with substantial financial investments. For its application to become more generalized, a script was written to provide an alternative application in the program Praat. This DSI v.02.03 corresponds with the following formula:
DSI v.02.03 = 1.127 + (0.164 x maximum phonation time) + (0.0053 × maximum fundamental frequency) – (0.038 x softest intensity) – (5.30 x jitter ppq5)
Consult Maryn et al. (2017) for all details relating to these parameters and to read about the strong correlation between the original DSI and the DSI v.02.03.
Phonanium’s script for Dysphonia Severity Index v.02.03: specific features
- To determine the subject’s maximum phonation time.
- To rename the three seconds part of the sustained [a:] to ‘ppq’, after Praat’s ppq5 algorithm (so the object in the list is named ‘Sound pp.’).
- To rename the sample with vocalization(s) to one’s highest fundamental frequency to ‘fh’, after frequency highest (so the object in the list is named ‘Sound fh’).
- To rename the sample with vocalization(s) to one’s softest intensity level to ‘il’, after intensity softest (so the object in the list is named ‘Sound il’).
Pre-analysis functions and formatting
Before analyzing the voice/speech signal, the user is prompted in a form:
- to fill in the maximum phonation time;
- to decide on the threshold score (1.6 by default);
- to choose if an intensity level calibration factor is to be implemented, and if yes, whether a new calibration factor has to be applied;
- to enter personal information (i.e., name, date of birth, date of assessment and additional information) directly in this form, or to take this information after having it entered in the form of the Phonanium script entitled ‘Personal information’.
Graphical information output
- DSI bar.
Numerical/statistical information output
- Praat’s jitter ppq5
- Maximum fundamental frequency
- Softest intensity of voiced speech
- Maximum phonation time
- Dysphonia Severity Index v.02.03
Important: calibration of vocal intensity level measurement
For clinical measurements of vocal intensity levels in the vocal range estimation to be reliable, it is essential to be calibrated before recording and analyzing sound signals (Ma, 2011). A straightforward method for calibration of the vocal intensity level has been described and found feasible, valid and accurate by Maryn & Zarowski (2016). This script automatically calibrates your intensity level measures when these data have been implemented/completed.
Click here to visit PHONANIUM’s page on vocal intensity level calibration.
Important: quality of sound recording
Many of the acoustic analyses and clinically relevant voice markers in the scripts of PHONANIUM imply sophisticated and complex procedures. However, when they are run on signals with bad recording quality, they loose their clinical value in terms of validity and reliability. So, prior to undertaking high-standard acoustic voice analyses, clinicians have to make well-considered choices in all of the following elements in the audio recording chain: room acoustics and ambient noise, type and placement of microphone, microphone preamplifier, and digital audio capturing device. To sample all relevant vocalizations and speech tokens as least polluted by recording-related noise as possible is what it essentially comes down to. For example Maryn (2017) offers an overview on how to deal with this.
Click here to visit PHONANIUM’s page on how to minimize recording-related influences on voice/speech signals.
Important: use the ‘Personal information’ script
With the script ‘Personal information v.01.02’ the user can complete an electronic form with the subject’s/patient’s name, date of birth, date of assessment, and optionally extra information. All this information (a) is than written into a table, (b) will be consulted by the other PHONANIUM scripts if the option “Take from ‘Table personalInformation’” is selected, and (c) will be written automatically in the output of these scripts. This increases the user-friendliness of working with PHONANIUM scripts in the program Praat, as the user/clinician has to complete this personal information only once during the entire voice assessment session.
Click here to visit PHONANIUM’s page on this ‘Personal information v.01.02’ script.
For customers in the EU: this software currently has no CE certification. We are in the process of application. In the meantime, this software can be used for scientific as well as educational/learning purposes.
Click here to visit the website where the program Praat (Paul Boersma & David Weenink, Institute for Phonetic Sciences, University of Amsterdam, The Netherlands) can be downloaded. This software runs under the GNU General Public License. Click here to download this license.
Aichinger P, Feichter F, Aichstill B, Bigenzahn W, Schneider-Stickler B (2012). Inter-device reliability of DSI measurement. Logopedics Phoniatrics Vocology, 37, 167-173.
Awan SN, Ensslen AJ (2010). A comparison of trained and untrained vocalists on the Dysphonia Severity Index. Journal of Voice, 24, 661-666.
Maryn Y, Corthals P, De Bodt M, Van Cauwenberge P, Deliyski D (2009). Perturbation measures of voice: a comparative study between multi-dimensional voice program and praat. Folia Phoniatrica et Logopaedica, 61, 217-226.
Maryn Y, Zarowski A (2015). Calibration of clinical audio recording and analysis systems for sound intensity measurement. American Journal of Speech-Language Pathology, 24, 608-618.
Maryn Y, Morsomme D, De Bodt M (2017). Measuring the Dysphonia Severity Index (DSI) in the program Praat. Journal of Voice, Feb 7, Epub ahead of print.
Wuyts FL, De Bodt MS, Bruckers L, Molenberghs G (1996). Research work of the Belgian Study Group on Voice Disorders 1996. Results. Acta Oto-Rhino-Laryngologica Belgica, 50, 331-341.
Wuyts FL, De Bodt MS, Molenberghs G, Remacle M, Heylen L, Millet B, Van Lierde K, Raes J, Van de Heyning PH (2000). The Dysphonia Severity Index: an objective measure of vocal quality based on a multiparameter approach. Journal of Speech, Language, and Hearing Research, 43, 769-809.
Additional reading on Dysphonia Severity Index
De Bodt M, Maryn Y (2013). Contemporary voice research: a Belgian perspective. In Yiu E (Ed.). International perspectives on voice disorders. Bristol, UK: Multilingual Matters, 190-203.
Dysphonia Severity Index v.02.03, 27/01/2019
- Addition of a free field for the gender entry under ‘personal information’, to account for issues related to gender diversity.