Empirical Investigation of the Acoustic Properties of Selected Nigerian Timbers for Musical Instrument Fabrication

The acoustic properties of wood including specific elastic modulus, internal friction damping, and acoustic radiation coefficient determine its suitability for musical instrument applications such as soundboards, back plates, and resonating bodies. Nigerian tropical timbers represent an underexplored resource for instrument-grade tonewoods, with limited published acoustic characterization data. This study empirically investigates the acoustic properties of eight Nigerian timber species including iroko, obeche, opepe, agba, apa, afara, mahogany, and pterygota, with specimens sourced from commercial timber yards in Oyo State, South West Nigeria. Resonant vibration testing was applied to standardized beam specimens to extract longitudinal and transverse sound velocity, dynamic Young's modulus, shear modulus, and internal friction loss factor using the free-free beam vibration method. Acoustic radiation coefficient and Schelleng quotient were derived from measured parameters as figures of merit for soundboard applications. Results indicate that obeche and agba specimens exhibit specific modulus and radiation coefficient values comparable to Sitka spruce, the international standard tonewood, making them viable candidates for guitar soundboard applications. Iroko shows superior hardness and damping properties suitable for drum shell and body applications. Principal component analysis of acoustic parameters separates species into distinct performance clusters mapped to instrument application categories. The study establishes a Nigerian tonewood acoustic database and recommends standardized acoustic grading criteria for integration into the certification framework of the Forestry Research Institute of Nigeria. Keywords: acoustic properties, timber, musical instruments, tonewood, Nigeria