Transmission of droplet-conveyed infectious agents such as SARS-CoV-2 by speech and vocal exercises during speech therapy: preliminary experiment concerning airflow velocity.

PURPOSE: Infectious agents, such as SARS-CoV-2, can be carried by droplets expelled during breathing. The spatial dissemination of droplets varies according to their initial velocity. After a short literature review, our goal was to determine the velocity of the exhaled air during vocal exercises. METHODS: A propylene glycol cloud produced by 2 e-cigarettes' users allowed visualization of the exhaled air emitted during vocal exercises. Airflow velocities were measured during the first 200 ms of a long exhalation, a sustained vowel /a/ and varied vocal exercises. For the long exhalation and the sustained vowel /a/, the decrease of airflow velocity was measured until 3 s. Results were compared with a Computational Fluid Dynamics (CFD) study using boundary conditions consistent with our experimental study. RESULTS: Regarding the production of vowels, higher velocities were found in loud and whispered voices than in normal voice. Voiced consonants like /ʒ/ or /v/ generated higher velocities than vowels. Some voiceless consonants, e.g., /t/ generated high velocities, but long exhalation had the highest velocities. Semi-occluded vocal tract exercises generated faster airflow velocities than loud speech, with a decreased velocity during voicing. The initial velocity quickly decreased as was shown during a long exhalation or a sustained vowel /a/. Velocities were consistent with the CFD data. CONCLUSION: Initial velocity of the exhaled air is a key factor influencing droplets trajectory. Our study revealed that vocal exercises produce a slower airflow than long exhalation. Speech therapy should, therefore, not be associated with an increased risk of contamination when implementing standard recommendations.

Alterations in Emotional Expression Through Speech in Patients With Unilateral Vocal Fold Paralysis: A Preliminary Study.

Unilateral vocal fold paralysis (UVFP) has a known impact on patients' quality of life. One of the potentially affected domains that has not been studied yet is emotional prosody. To produce and transmit an efficient emotional prosody, several vocal parameters are modulated by the speaker, principally the fundamental frequency, the speech rate, and the voice intensity. We retrieved 300 sentences produced by 10 patients suffering from UVFP, equally in neutral, anger, and sadness. A jury of six health care voice experts was asked to hear these sentences and choose an emotion for each vocalization, between neutral, anger, and sadness. The jury mainly considered the heard sentences as being in a neutral emotion. Vocal parameters analysis of the anger and sadness sentences that were mistaken as neutral showed the absence of significant difference in their fundamental frequencies and speech rates. By being unable to modulate their vocal parameters as needed to produce emotional prosody, specifically the fundamental frequency and speech rate, patients with UVFP suffer from limitations in their capacity to produce the emotional prosody wanted, making the emotions they feel hardly transmitted to their entourage, which can explain the social barriers these patients complain of.