Acoustic characteristics of vocal oscillations: Vibrato, exaggerated vibrato, trill, and trillo

Acoustic analysis was performed on recordings of 10 early music singers producing examples of vibrato, exaggerated vibrato, whole-tone trill, and trillo to obtain measures of oscillation rate, frequency extent, and jitter. Oscillation rates for vibrato, exaggerated vibrato, and trill were similar, but trillo rate was much faster. Average frequency extent of oscillation was 1 semitone (st) for vibrato, 2.21 st for exaggerated vibrato, 2.71 st for whole-tone trill, and 1.64 st for trillo. Jitter measures indicated that exaggerated vibrato had the most stable oscillations and trillo the least.     

Comparing historical and contemporary opera singers with historical and contemporary Jewish cantors

This study is an attempt to ascertain if singers from different traditions and milieus follow similar aesthetic trends regardless of training and/or background. Cantors who sang the Jewish synagogue liturgy during the Golden Age of cantorial singing prior to World War II came from Eastern and Central Europe. For the most part, they were not trained in the classical Western opera tradition. They received training from choir leaders and other cantors and the training was primarily in the modes of synagogue chant. Cantors today receive the same kinds of training that opera singers receive, often from the same teachers. Four groups of singers, consisting of four singers in each group, were utilized in this study. The four groups are: historical opera singers, contemporary opera singers, historical cantors, and contemporary cantors. The historical opera singer recordings date from as early as 1909 to as late as 1939. It was not possible to determine the dates of the historical cantor recordings. However, the four cantors chosen for this group were active only to the 1940s. Contemporary samples were taken from CDs and/or live recordings and all the singers from the contemporary groups are either still active or were active in the 1960s through the 1980s and all of them are considered to be premier-level singers in their respective areas. The variables analyzed were: vibrato pulse rate, frequency variation of the vibrato pulse above and below the mean sustained sung frequency in percent, the mean amplitude variation of the amplitude vibrato pulse above and below the mean sustained amplitude in percent and the fast Fourier transform (FFT) power spectrum of the sustained samples. Results indicate that most of the significant differences were found between eras and not between groups within a time period.     

Measurement of formant frequencies and bandwidths in singing

That singers under certain circumstances adjust the articulation of the vocal tract (formant tuning) to enhance acoustic output is both apparent from measurements and understood in theory. The precise effect of a formant on an approaching (retreating) harmonic as the latter varies in frequency during actual singing, however, is difficult to isolate. In this study variations in amplitude of radiated sound components as well as supraglottal and subglottal (esophageal) pressures accompanying the vibrato-related sweep of voice harmonics were used as a basis for estimating the effective center frequencies and bandwidths of the first and second formants.     

Acoustical Comparison Between Samples of Good and Poor Vibrato in Singers

The purpose of this research was to analyze samples of frequency vibrato taken from recordings of eight different singers, which were classified as examples of good or poor singing. The samples were analyzed by a software package, which makes use of the linear prediction coding (LPC) method to determine the time varying rate and extent of the frequency vibrato wave. Four parameters, which relate to the periodicity of the samples, were extracted from the time varying rate and extent and investigated in order to verify or reject the hypothesis that the best vibrato samples were the most symmetric ones. Ten samples per singer were analyzed, 5 good and 5 poor, for a total of 80 samples. The results show that the samples judged as good were the most periodic ones.     

Measurements of vibrato parameters in long sustained crescendo notes as sung by ten sopranos

Two high-pitched and long sustained notes, F5 and A5, were selected from an aria found in ten commercial recordings of G Verdi's opera Aida by ten different sopranos. Both notes were sung without any instrumental accompaniment and with a crescendo. These audio examples were analyzed with regard to fundamental frequency, vibrato rate, vibrato extent, intonation and sound level, and the relationship among these parameters. The results reveal that vibrato rate differed significantly between the tones in most of the singers and confirm Prame's observations that vibrato rate tends to increase exponentially toward the end of tones. Moreover, both vibrato extent and mean F0 often varied systematically with sound level. The regularity of the vibrato tended to be greater at F5 than at A5.     

Synthesizing choir singing

Analysis by synthesis is a method that has been successfully applied in many areas of scientific research. In speech research, it has proven to be an excellent tool for identifying perceptually relevant acoustical properties of sounds. This paper reports on some first attempts at synthesizing choir singing, the aim being to elucidate the importance of factors such as the frequency scatter in the fundamental and the formants. The presentation relies heavily on sound examples.