Acoustics of the banjo: measurements and sound synthesis

• Main Authors: Woodhouse Jim, Politzer David, Mansour Hossein
• Format: Article
• Language: English
• Published: EDP Sciences 2021-01-01
• Series: Acta Acustica
• Subjects: banjo; acoustics; vibration; synthesis
• Online Access: https://acta-acustica.edpsciences.org/articles/aacus/full_html/2021/01/aacus200055/aacus200055.html

Measurements of vibrational response of an American 5-string banjo and of the sounds of played notes on the instrument are presented, and contrasted with corresponding results for a steel-string guitar. A synthesis model, fine-tuned using information from the measurements, has been used to investigate what acoustical features are necessary to produce recognisable banjo-like sound, and to explore the perceptual salience of a wide range of design modifications. Recognisable banjo sound seems to depend on the pattern of decay rates of “string modes”, the loudness magnitude and profile, and a transient contribution to each played note from the “body modes”. A formant-like feature, peaking around 500–800 Hz on the banjo tested, is found to play a key role. At higher frequencies the dynamic behaviour of the bridge produces additional formant-like features, reminiscent of the “bridge hill” of the violin, and these also produce clear perceptual effects.