Why MDS for voice analysis?
Role of MDS for voice analysis
Parameters of voice:
To fully appreciate the use of MDS for voice analysis, one must first recognize the complexity of the human voice:
Parameters of Voice
|Rate of vf vibration||frequency--fo,cps, Hz||pitch|
|Amplitude of vf vibration||SPL, intensity--dB||loudness|
|Periodicity of vf vibration (stability)||perturbation-jitter,shimmer||quality|
|Complexity of vf vibration||range||flexibility|
Graph obtained from class notes: CD 583 (Leeper, 2001)
The parameters of voice can be considered multidimensional in nature. Furthermore, "little is known about the way various parameters interrelate to result in the unique and distinctive vocal quality of an individual." (Kemster, 1991)
As a result of the complex nature of the human voice, dramatic differences exist regarding: disciplinary perspectives, levels of training, experience, and available instruments for evaluating voice disorders.
is a wide assortment of variables that are possible targets for quantification.
Potentially relevant phenomena and indices include, to name a few, Fo, vocal intensity,
mean glottal airflow, instantaneous glottal volume velocity (via inverse filtering), air
pressure, vocal fold motions (via stroboscopy), frequency and intensity perturbation,
vocal fold contact area (via electroglottography), and the laryngeal electromyograms...
The lack of internal agreement about which of these (or other) measures are most useful,
either alone or in combination, is particularly glaring and strongly inhibits the application
of any." (Bless & Baken, 1992)
According to Andrews (1999), there are no existing guidelines to standardize the selection and implementation of the wide variety of vocal function tests. This warrants the need for further research to ensure the use of reliable methods for determining voice quality and voice disorders.
Association for Logopedics and Phoniatrics (IALP) established a
voice committee to examine issues and make recommendations concerning the standard-
ization of voice evaluation procedures. This committee has published a survey along
with report in hopes to stimulate professional dialogue in this area:
"In the next decade there will undoubetedly be wide discussion and hopefully some
resolution of critical issues such as calibration requirements, testing environments,
and examiner qualifications." (Andrews, 1999)
Carroll & Arabie (1980), stated that, "explosive growth" has occurred in the number and variety of models and methods, along with the proliferation of applications of MDS within many different fields. Unfortunately, "MDS remains an area characterized by a considerable lag between new metholological developments and routine used by nonspecialists."
Considering the "multidimensional" nature of the human voice, consideration of the following points is strongly urged:
Past research literature for voice parameters is limited and has failed
to fully develop
parameters for organizing concepts and underrlying dimensions.
2) MDS may provide further detection of patterns and structures that lie hidden in
large amounts of data.
3) MDS can promote accurate interpretation and application of data by representing the
data in forms more accessible to the human eye. Thus, contributing to our
further understaning of the human voice.
"I think it is an important and underused statistical tool."
Special Interest Division 3 (SID 3) member commenting on MDS
Deirdre D. Michael, Ph.D., CCC-SLP
MDS has (and continues to) contribute to our knowledge of the human voice.
The following is a list of published studies that employed MDS for voice analysis:
Zraick, Richard I., et.al. (2000). Multidimensional Scaling of Nasal Voice Quality.
Journal of Speech , Language and Hearing Research, 43: 989-996.
Assessment of Speech and Voice Disorders. AJSLP, (5).
quality. J.Acoust. Soc. Am., 100(3).
Tutorial, and a Framework for Future Research. Journal of Speech and Hearing
Research, 36: (21-40).
Quality in Females. Phonetica, 50: 15-27.
Journal of Speech and Hearing Research, 35: 512-520
Scaling Analysis of Dysphonia in Two Speaker Groups. JSHR, 34: 534-543.
Perception of Voice Quality. Journal of Speech and Hearing Research, 33: 103-115
"What we need are more people who specialize in the impossible."
Cummins - 2001