Extreme Vocal Effects Distortion, Growl, Grunt, Rattle, and Creaking as Measured by Electroglottography and Acoustics in 32 Healthy Professional Singers.

Unlabelled: Vocal effects - also called extreme or extended vocal techniques - with the intention to sound hoarse or rough are widely used as part of many genres and styles of singing, yet scarcely documented in research. Physiological studies detail the involvement of supraglottic structures for the production of vocal effects, yet the acoustic impact of such involvement has not been documented systematically across phonation types.

Purpose: To report acoustic measurements and electroglottography-specific measurements for the five rough-sounding vocal effects Distortion, Growl, Grunt, Rattle, and Creaking across phonation types to demonstrate differences between notes with and without vocal effects added.

Methods: Thirty-two professional singers and singing teachers produced sustained vowels in each of the four vocal modes with alternations of adding and removing the vocal effects. The singers were recorded with a microphone at a constant distance as well as with EGG.

Results: The vocal effects Distortion, Growl, Grunt, Rattle, and Creaking impact the acoustic spectra in separate and systematic ways across genders and phonation types. Each vocal effect impacted the spectrum in specific and particular frequency regions between 0 and 3.5 KHz as well as in higher partials after 12 kHz with statistical significance. EGG-waveforms were un-impacted by most of the vocal effects produced using supraglottic sound sources, whereas Grunt and Creaking conditions did impact EGG-waveform signals, though not consistently between participants. EGG measures confirmed sustained and unchanged Qx and Fx for most conditions, with statically significant changes in noise measurements Harmonic-to-Noise Ratio, Normalised Noise Energy, Relative Average Perturbation, and Cepstral Peak Prominence, despite Sound Pressure Level differing significantly only for a few specific conditions. Singers scored an average of 5,95 on Voice Handicap Index questionnaires and were all reportedly healthy.

Conclusions: Vocal effects added to phonation produce specific increases and specific decreases in particular frequency regions in a systematic way and can be produced in a healthy and sustainable manner, as measured by Voice Handicap Index. Vocal effects can be added to different phonation types with differing acoustic output and singers were able to sustain and control involvement of the supraglottic sound source(s) independently of phonation type.