Quantitative voice quality analyses of a soprano singing early music in three different performance styles

This paper considers the measurement of voice quality variations relating to three different performance styles of early music singing by a trained soprano. In particular, the various outputs available following the collection of electrolaryngographic data are presented along with acoustic analyses based on the acoustic pressure waveform to enable a comparison of the three different singing styles. Voice quality analysis is based on the output from the electrolaryngograph, that enables a measurement of fundamental period to 1 μs accuracy to be made, enabling fundamental frequency variations including vibrato to be explored. In addition, the percentage of each cycle for which the vocal folds are in contact is measured and varies between the three voice qualities providing insights into the nature of vocal fold vibration in each case. Acoustic output spectral measures are made that are not only based on traditional wide- and narrow-band but also hearing modelling spectrography. These provide a clear indication as to which portions of the spectrum are most prominent in terms of perception of the three different voice qualities. A number of features resulting from the various analyses distinguish the singing styles, thereby providing evidence that the methods used are appropriate for objective characterisation and differentiation of singing styles in early music.