4 LAMINAGRAPHIC STUDIES OF VOCAL FOLD THICKNESS

Conventional laminagraphy was utilized to quantify vocal fold thickness at selected frequency/intensity combinations in four separate studies.In the first study, individual and group trends suggest that small changes of vocal fold thickness are correlated with fairly large changes if f0; a result in agreement with previous research.In a second study, vocal intensity was the experimental variable. Vocal fold thickness increased as function of increasing vocal intensity; however, vocal fold area (from which the thickness values were derived) failed to display a similar relationship.Two other investigations were conducted in order to study vocal fold thickness variation primarily as related to falsetto. Similar patterns were found for high modal and low falsetto phonation. However, for a series of high falsetto phonations (above 50 tones FL), vocal fold thickness appeared to exhibit little systematic relationship to frequency change.The following conclusions are suggested: (1) frequency change in the modal register is closely correlated with the (per-unit) mass of the vocal folds, (2) vocal folds mass varies with corresponding changes of vocal intensity, although this may be a passive reaction and (3) for low falsetto frequencies, vocal fold thickness changes in a fashion similar to the modal register whereas at higher falsetto frequencies, vocal fold thickness apparently does not play a significant part in frequency variation. © 1969 S. Karger AG, Basel.