The intensities of vowels and plosive bursts and their impact on text intelligibility in singing

Abstract

In classical singing, there are often problems with the intelligibility of sung text. The present study aims to test the hypotheses that (1) in loud operatic singing, compared with speaking, the intensity of voiceless plosives increases less than the intensity of vowels, leading to poorer recognition of plosives; and (2) pronouncing the plosive bursts with greater intensity improves their recognition. The acoustic analysis of nine opera arias in Italian from the Classical and Romantic periods performed by ten classically trained singers showed that the average difference in the intensity of vowels when sung and spoken was 14.6 dB [standard deviation (SD) = 7.2 dB], while the difference in the intensity of voiceless plosive bursts was only 6.6 dB (SD = 6 dB). In a perception test with 73 participants, increasing the intensity of the plosive bursts generally improved the recognition of plosives in the sung /a–plosive–a/ sequences, but mainly when reverberation and/or pink noise imitating instrumental accompaniments were added to the stimuli. At the same time, recognition of plosives was often better than chance even when the plosive burst was missing and replaced by silence.