2014 Volume 55 Issue 2 Pages 167-172
This study evaluated the reproducibility of measurements of facial skin vibration during singing by a scanning laser-Doppler vibrometer. A laser-Doppler vibrometer is an optical transducer capable of measuring the vibration velocity and the displacement of a certain point of a vibrating object on the basis of optical Doppler effect. A scanning vibrometer can scan and probe multiple predetermined points of a vibrating surface automatically. Three trained singers participated in this study. They sat with their head in a fixed position by attaching their forehead to the frame of a chin receiving stand. During the measurement, they were asked to sing the Japanese vowel /a/ in their comfortable pitch height continually, and the vibration velocity of the facial skin surface was obtained only during voicing. The results of three measurements for each participant showed that the root mean square errors of the vibration velocity were less than 4.0 dB. Moreover, the probability of outliers of the measurements, which were defined as measurement points whose vibration velocity was more than 6 dB apart from the median of the measured values, was 2.4%. Many of the outliers occurred at rounded facial surfaces where it was difficult to observe a reflected laser beam.
