Acoustic Voice Quality Index to measure straining and recovery
Semiocclusions and voice rest as recovery exercises
Keywords:
active recovery, AVQI, passive recovery, vocal strainingAbstract
This study examined how AVQI responds to vocal loading and following recovery. The effects
of recovery were also compared between two active recovery exercise groups (water resistance
therapy and nasal exercise) and one control group (silent rest). Each of the 30 participants
first read a random passage of text loudly (15 min.) as a vocal loading task. Thereafter the
participants were divided into three groups according to the three recovery methods. The
final phase of the study consisted of 10 minutes of passive rest for each group. Recordings
were made before and after loading, active recovery, and passive recovery. AVQI and Sound
Pressure Level (SPL) were analyzed from the recordings. Vocal straining significantly increased
perturbation (shimmer) and SPL. After the straining, the change in spectral Tilt correlated
negatively with subjective straining sensations. After recovery, shimmer decreased and
harmonics-to-noise ratio and Tilt increased. The three recovery groups differed significantly
from each other in regard to how SPL changed during the recovery periods (RM-ANOVA,
(F(2, 25), p = 0,038). SPL increased in water resistance group and decreased in the other
groups. The increase in water resistance group may reflect higher subglottic pressure or
lowered phonation threshold. Water bubbling in water resistance therapy may have massage
like effects on vocal fold tissue and increase blood flow, thus speeding up recovery
