Affordable wide-band measurement ecosystem for musical acoustics based on electro-dynamic transducers

Abstract

The variability in responses of acoustic instruments can be attributed to a combination of fluctuations in critical parameters of wood, such as density, stiffness, and strength, and design features such as body shapes or bracing geometries. Recent studies have successfully implemented the sine sweep method with small exciters to measure the acoustic response of guitars, yielding frequency responses with high coherence over a bandwidth reaching up to 8 kHz. This paper proposes validating a cost-effective measurement system which integrates electro-dynamic transducers and wide-band test signals (sine sweep and noise) against the traditional impact hammer method in the case of unbraced plates. Data from four actuators of different size and power will be presented together with a simple strategy to assess reliable and neutral excitation points, thanks to two complementary models which describe the interaction between exciter and plate. The paper will then showcase the applications of this measurement system in two scenarios. The first case study will focus on a cost-effective method for selecting acoustic wood, while the second will explore experimental real-time spectral analysis using pink noise. These case studies demonstrate the measurement system’s adaptability and immediacy, providing valuable insights for enhancing the design and performance of acoustic instruments.

Keywords

• acoustic measurements
• musical acoustics
• exponential sine-sweep
• soundboards
• exciter
• impedance measurements