Resonance Tube or Lax Vox?

Area of Science:

• Voice production and acoustics
• Bioacoustics
• Speech science

Background:

• Resonance tubes (RT) and Lax Vox tubes (LVT) are used in voice therapy.
• Understanding their aerodynamic and acoustic properties is crucial for effective clinical application.

Purpose of the Study:

• To compare the flow resistance of RT and LVT.
• To investigate phonation into these tubes at different submersion depths (2cm and 10cm) and angles.
• To analyze the effects on oral pressure, vocal fold contact, and sound pressure level.

Main Methods:

• In vitro: Measured air pressure for flow rates (60-600 mL/s) at varying submersion depths (2cm, 10cm) and angles (30°, 45°, 90°).
• In vivo: 14 subjects phonated into RT (45° immersion) and LVT (90° immersion) at 2cm and 10cm submersion depths.
• Measured oral pressure, electroglottographic contact quotient, and sound pressure level; subjective sensations were reported.

Main Results:

• Flow resistance was slightly lower for LVT compared to RT, and decreased with smaller immersion angles.
• During habitual loudness phonation, LVT resulted in lower transglottic pressure and oral pressure variation frequency, but higher oral pressure variation amplitude at 2cm submersion.
• Subjective preferences for RT or LVT varied among participants.

Conclusions:

• RT and LVT exhibit minor differences in flow resistance.
• The increased oral pressure oscillation observed with LVT at 2cm submersion may enhance vocal fold vibratory feedback and therapeutic effect.