Instrumental and perceptual evaluations of two related singers

Vocal resistance among choir singers

PURPOSE

The purpose of the present study was to compare the voice of choir singers before and after 60 min of singing and after an absolute rest.

METHODS

Twenty-one female choir singers aged on average 26.59 years, with experience in choir singing of at least one year were instructed to emit the vowel /a/ before and after singing and after a vocal rest of 30 min for an analysis of acoustic measures, and for the evaluation of their tactile-kinesthetic self-perception. Vocal warm-up was performed for 10 min. The participants were instructed to sing the "Ave Verum" music continuously for 60 min.

RESULTS

f0 (p = 0.0001) and Flo (p = 0.0002) increased after the singing test and were reduced after the vocal rest, in contrast to Fhi (p = 0.001), which continued to be increased compared to the pre-test measure even after the vocal rest. The vAm parameter (p = 0.05) was reduced after continuous singing and rest. All self-evaluation symptoms increased after the continuous singing task and were reduced after the 30 min rest, except for complaints of low voice, pain when swallowing and cough/throat clearing.

CONCLUSION

60 min of continuous use of the singing voice induced signs of vocal fatigue with an increase in f0, with improvement of symptoms and a reduction of f0 occurring after 30 min of vocal rest.

Perturbation and nonlinear dynamic analysis of different singing styles

Previous research has used perturbation analysis methods to study the singing voice. Using perturbation and nonlinear dynamic analysis (NDA) methods in conjunction may provide more accurate information on the singing voice and may distinguish vocal usage in different styles. Acoustic samples from different styles of singing were compared using nonlinear dynamic and perturbation measures. Twenty-six songs from different musical styles were obtained from an online music database (Rhapsody, RealNetworks, Inc., Seattle, WA). One-second samples were selected from each song for analysis. Perturbation analyses of jitter, shimmer, and signal-to-noise ratio and NDA of correlation dimension (D(2)) were performed on samples from each singing style. Percent jitter and shimmer median values were low normal for country (0.32% and 3.82%), musical theater (MT) (0.280% and 2.80%), jazz (0.440% and 2.34%), and soul (0.430% and 6.42%). The popular style had slightly higher median jitter and shimmer values (1.13% and 6.78%) than other singing styles, although this was not statistically significant. The opera singing style had median jitter of 0.520%, and yielded significantly high shimmer (P=0.001) of 7.72%. All six singing styles were measured reliably using NDA, indicating that operatic singing is notably more chaotic than other singing styles. Median correlation dimension values were low to normal, compared to healthy voices, in country (median D(2)=2.14), jazz (median D(2)=2.24), pop (median D(2)=2.60), MT (median D(2)=2.73), and soul (mean D(2)=3.26). Correlation dimension was significantly higher in opera (P<0.001) with median D(2)=6.19. In this study, acoustic analysis in opera singing gave significantly high values for shimmer and D(2), suggesting that it is more irregular than other singing styles; a previously unknown quality of opera singing. Perturbation analysis also suggested significant differences in vocal output in different singing styles. This preliminary study using acoustic analysis with nonlinear dynamic measures and perturbation measures may represent a valuable procedure in quantitatively describing the properties of the singing voice. Further research with human test subjects may allow us to characterize singing styles and diagnose vocal dysfunction in the singing voice.