Quantification of Respirable Aerosol Particles from Speech and Language Therapy Exercises

Area of Science:

• Acoustic and aerodynamic analysis of voice production.
• Respiratory aerosol generation and transmission dynamics.
• Infectious disease control in healthcare settings.

Background:

• Voice assessment and therapy involve manipulating subsystems of voice production.
• These procedures can generate respirable aerosol particles, increasing the risk of viral transmission (e.g., SARS-CoV-2) compared to normal breathing or speech.

Purpose of the Study:

• To characterize the production of respirable aerosol particles during various voice assessment and therapy tasks.
• To quantify aerosol generation across different vocal activities and compare them to breathing and speaking.

Main Methods:

• Recruited 23 healthy adults (11 speech-language pathologists specializing in voice disorders).
• Measured aerosol number concentration and particle size distribution using aerodynamic and optical particle sizers.
• Conducted measurements in a laminar flow operating theatre to ensure accurate quantification of generated aerosols.

Main Results:

• Voice tasks generated up to 32 times more aerosol particles and 163 times more aerosol mass than breathing.
• Activities produced up to 24 times more aerosol particles and 36 times more aerosol mass than speech.
• Water resistance therapy (WRT) generated the highest aerosol concentrations, exceeding speaking by 10 times and breathing by over 30 times.

Conclusions:

• All voice assessment and therapy activities produced more aerosols than breathing, with some comparable to speech.
• Higher airflow activities, particularly those involving intraoral pressure oscillation (e.g., WRT, trilling), generated larger particle concentrations and sizes.
• Findings underscore the potential for increased aerosol generation during voice interventions, necessitating consideration for infection control.