Regime change in the recorder: Using Navier-Stokes modeling to design a better instrument

Area of Science:

• Acoustics
• Fluid Dynamics
• Musical Instrument Design

Background:

• The recorder's lowest note is produced with all toneholes closed at moderate blowing speeds.
• Increasing blowing speed causes an abrupt shift to an octave higher note, known as regime change.
• Anecdotal evidence suggests bass recorders exhibit regime change at lower blowing speeds than higher-pitched instruments.

Purpose of the Study:

• To investigate the phenomenon of regime change in recorders.
• To model and understand differences in regime change behavior across the recorder family.
• To explore design modifications for improving recorder playability.

Main Methods:

• Utilizing Navier-Stokes modeling to simulate recorder acoustics and fluid dynamics.
• Developing a computational model of the bass recorder to analyze regime change.
• Conducting experimental studies on modified real recorders.

Main Results:

• Navier-Stokes modeling confirmed differences in regime change thresholds among recorder types.
• Modeling demonstrated that altering labium geometry can increase the regime change threshold in bass recorders.
• Experimental results validated the modeling predictions, showing improved performance with modified designs.

Conclusions:

• The study provides a scientific basis for understanding recorder regime change.
• Geometric modifications near the labium offer a method to enhance recorder playability.
• These findings can inform the design of new, more user-friendly recorders.