Macro parameters describing the mechanical behavior of classical guitars

Area of Science:

• Musical Acoustics
• Vibrational Analysis
• Instrument Mechanics

Background:

• Simplified models for string instrument vibro-acoustics exist, but primarily for low frequencies.
• A need exists for characterizing instrument mechanics over broader frequency ranges using workshop-friendly measurements.

Purpose of the Study:

• To present a method for deriving and estimating key mechanical features of classical guitars.
• To identify parameters suitable for workshop measurements and capable of discriminating between guitar classes.

Main Methods:

• Utilized high-resolution subspace ESPRIT (Estimation of Signal Parameters via Rotational Invariant Techniques) and ESTER (ESTimation of ERror) for modal parameter estimation.
• Applied methods to experimental data from metal and wood plates and numerical simulations.
• Selected four characteristic features: Mass, rigidity, characteristic admittance, and mobility deviation.

Main Results:

• Demonstrated nearly constant mode density in mid- and high-frequency ranges for guitars, similar to flat panels.
• Identified four features (Mass, rigidity, characteristic admittance, mobility deviation) as characteristic parameters of the equivalent plate.
• Showed that these features effectively discriminate between different classes of classical guitars in a study of 12 instruments.

Conclusions:

• The proposed method provides a practical approach to characterizing classical guitar mechanics.
• The identified features are valuable for classifying and understanding variations in classical guitars.
• This research bridges advanced modal analysis with practical instrument making insights.