Variability of electroglottographic glottal closed quotients: necessity of standardization to obtain normative values.
OBJECTIVE
To demonstrate the variability of electroglottographic measurements of the glottal closed quotient (GCQ) in normal subjects by the calculation method used, fundamental frequency, and intensity.


METHODS
Prospective study.


METHODS
Tertiary university-based referral center.


METHODS
Twenty healthy male volunteers without laryngeal disorder. Three successive sustained productions of the vowel /a/ were performed by each subject. Electroglottographic recordings of GCQ were obtained using the criterion level method, which defines an approximate duration of glottal closure and opening. Glottal closed quotient values were calculated based on criterion levels ranging from 10% to 40%.


METHODS
The extent of correlation between GCQ variation and the mean fundamental frequency and intensity.


RESULTS
As the criterion level increased, a decrease in the mean GCQ was recorded, which was significant with a 10% criterion level increase, up to a critical level of 25%. A significant positive correlation was found between GCQ and the variables of fundamental frequency and intensity.


CONCLUSIONS
This study demonstrated significant effects of the criterion level used, fundamental frequency, and intensity in the determination of normative values of GCQ. Normative values can only be assessed through the standardization of one criterion level reached by consensus.
Kania
Romain E
RE
Voice, Biomaterials, and Head and Neck Oncology Research Laboratory, Department of Otorhinolaryngology-Head and Neck Surgery, Georges Pompidou European Hospital, University of Paris V, Paris, France.
Hans
Stéphane
S
Hartl
Dana M
DM
Clement
Philippe
P
Crevier-Buchman
Lise
L
Brasnu
Daniel F
DF
D000328:Adult; D017097:Electric Impedance; D004576:Electromyography; D005931:Glottis / Q000502:physiology*; D006801:Humans; D008297:Male; D010699:Phonation / Q000502:physiology*; D011446:Prospective Studies; D012016:Reference Values; D014833:Voice Quality