“Lombard Effect” and Voice Changes in Adductor Laryngeal Dystonia: A Pilot Study.

Abstract

Objectives: The aim was to describe the acoustic, auditory-perceptive, and subjective voice changes under the Lombardeffect (LE) in adductor laryngeal dystonia (AdLD) patients.Methods: Subjective perception of vocal effort (OMNI Vocal Effort Scale OMNI-VES), Maximum Phonation Time (MPT),and the perceptual severity of dysphonia (GRBAS scale) were assessed in condition of stillness and under LE in 10 AdLDpatients and in 10 patients with typical voice. Speakers were asked to produce the sustained vowel /a/ and to read a phoneti-cally balanced text aloud. Using the PRAAT software, the following acoustic parameters were analyzed: Mean Pitch (Hz), Mini-mum and Maximum Intensity (dB), the Fraction of Locally Unvoiced Frames, the Number of Voice Breaks, the Degree of VoiceBreaks (%), the Cepstral Peak Prominence-Smoothed (CPPS) (dB).Results: Under LE, the AdLD group showed a decrease of both G and S parameters of GRBAS and subjective effort, meanMPT increased signi?cantly; in the controls there were no signi?cant changes. In both groups under LE, pitch and intensity ofthe sustained vowel /a/ signi?cantly increased consistently with LE. In the AdLD group the mean gain of OMNI-VES score andthe mean gain of each parameter of the speech analysis were signi?cantly greater than the controls’ ones.Conclusion: Auditory feedback deprivation obtained under LE improves subjective, perceptual-auditory, and acousticsparameters of AdLD patients. These ?ndings encourage further research to provide new knowledge into the role of the audi-tory system in the pathogenesis of AdLD and to develop new therapeutic strategies.Key Words: acoustic analysis, adductor laryngeal dystonia, audio-vocal feedback control, Lombard effect.Level of Evidence: 4Laryngoscope, 134:3754–3760, 2024