Assessing the geometry and tuning properties of historical timbilas through non-destructive reverse engineering techniques

• Autor(a) principal: Oliveira, Eduardo Fernandes Lopes de
• Data de Publicação: 2020
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/123600
• topic: Timbila; Engenharia reversa; Análise modal; Reverse engineering; Modal analysis; 3D scanning technology; African xylophones; Elementos Finitos; Scan 3D; Xilofones africanos; Domínio/Área Científica::Humanidades::Artes

Timbilas are xylophones finely manufactured and tuned by the Chopi people from Mozambique. In the context of a research project, we aim at assessing the construction and acoustical features of a set of historical instruments by developing non-destructive characterization techniques based on reverse engineering, with main objectives to assess their original tuning and musical scale. In this thesis, we present the methodology and workflow that have been developed for the study of the collection of historical timbilas of the National Museum of Ethnology of Lisbon, which is the world's largest collection of the Mozambican instrument. In a first stage, contactless geometrical measurements were performed on a ninebar timbila by using 3D scanning Technology, resulting in a detailed geometrical description of the instrument bars. In a second stage, the 3D collected geometrical data was used as input to Finite Element computations in order to calculate the modal frequencies and mode shapes of each bar of the instrument. Results stemming from our modal computations were compared with modal data obtained from vibrational measurements, proving the efficiency of the proposed approach. Final stage was using the data as input for developing a sound synthesis model for recreating the sound of the timbila bars.