Room influence on the acoustical footprint of a violin

Every violin has a unique acoustical footprint characterized by its sound transfer function (TF), and this study measures the influence of a room’s acoustical properties on that footprint. Using an omnidirectional microphone (centered, perpendicular, 20 cm from the bridge) and a force measurement hammer, we collect data across six rooms (having 0.5 to 2 s average reverberation times). After vibrationally isolating the violin and muting its strings, we tap the bridge’s upper left corner ten times and record 0.3 s audio files of each tap (48 kHz sampling rate). We estimate the TF by normalizing the sound pressure level data by the tap force measurement in frequency space. Analysis of TFs reveal variations due to violin angle. Between 250 and 1.5 k Hz, (frequency range containing the violin's characteristic A0, B1+, B1−, and transition hill modes), the average standard deviation within a 10-tap set on one day is 1 dB, and 2 dB across multiple days. Higher frequencies have more variation. Observations are not clearly tied to room size or reverberation time. The data suggest repeatable measurements of the characteristic violin modes in different acoustical environments are possible, though additional research across multiple days is necessary to confirm reproducibility.