The Characterization of Piano Soundboard Materials with Respect to their Vibrational and Psychoacoustical Properties for Evaluation Purposes.
Matt Borland · 2010
Understanding the contribution of different materials to the overall sound quality of a musical instrument is a complex problem. Piano builders have historically used an empirical, but subjective approach in their quest to create an ideal sound. One of the major challenges builders face is in the control of a piano’s tone with changes in humidity. Due to wood’s hygroscopic nature wooden components create internal stresses in a piano that affect its tone as the wood expands and contracts. Another challenge builders face is the loss of high quality wood resources due to poor logging practices. The creation of dimensionally stable wood alternatives is an attractive idea to address both of these issues. The material sciences will play a primary role in the development of an appreciation of the unique properties of wood typically used in piano construction to investigate the creation of satisfactory wood replacements. Establishing a connection between psychoacoustics and the perception of instrument tone will also be very important. This assessment is a difficult aspect of this problem as musicians would typically use subjective words like warm, brassy, dull, or sharp to describe the sound quality of an instrument. Computer modelling and experimental testing of thin rectangular panels for their sound production properties will allow for this connection to be made in a simple case which can then be extended to full size instruments. Relating wood and modern composite materials to their structural and acoustical properties will also be important and the testing of a small rectangular panel will allow for model verification and the evaluation of wood properties in an environment removed from the complexity of a full piano. The way a fully constructed piano produces sound will also be investigated in terms of its vibrational and sound producing properties to provide a contextual base for the discussion of how the materials used in a piano relate to its sound quality. Overall the simple goal of this aspect of the research work will be to provide quantitative data that can show how a change in soundboard material will result in a change in the overall tone of an instrument with respect to a specific descriptor such as warmth or brightness. Applying the results obtained from the simpler case of a rectangular panel to a soundboard in a musical instrument will then allow for the characterization of these materials in a musical context, something that is important in terms of the psychoacoustical evaluation of the materials. From this research work several new characterization techniques will be created along with dimensionally stable wood alternatives for use in piano construction. Ideally this work will allow piano builders to have more control over the tone of their instruments and will provide them with new techniques to quantitatively evaluate and characterize their instruments.