Perception of violin soundpost tightness through playing and listening tests

This study involved playing and listening (using recorded sounds) experiments to investigate how changes in soundpost length (for a fixed soundpost position) affect the perceptual qualities of the violin and what the threshold of change is below which players and luthiers do not perceive differences. A length-adjustable carbon fiber soundpost was employed. During the playing experiment, subjects played a provided violin on which the soundpost length was modified by the experimenter to find their optimal soundpost lengths. Then the experimenter varied the soundpost length randomly in ten trials within ±0.11 mm around their optimal lengths and asked subjects to always compare with the previous setting. The results showed that subjects' optimal soundpost lengths varied from 0.132 to 0.616 mm relative to the original length (53 mm), but subjects could not recognize length variation of 0.11 mm or less at above chance levels. During the listening experiment, subjects listened to 16 pairs of recordings through a computer interface and were asked, for each pair, whether the violin setup was the same or different. The results showed that subjects could differentiate soundpost lengths with a difference of about 0.198 mm at better than chance level.