Development of Helmholtz motion and related wave patterns in the bowed string

Abstract: Of the many wave patterns that the bowed string is capableof producing, the so-called?Helmholtz motion?(Helmholtz 1862) gives the fullest sound in terms of power andovertone richness. Papers one and two of this thesis deal withthe creation of this particular string movement: The firstpaper, based on computer analysis, describes some systemparameters?influence on the transient in terms of?playability?. The second paper deals with theperception of real violin attacks of different transientqualities. Not surprisingly, it can be shown that tone onsetsare considered superior when the attack noise has a verylimited duration. However, the character of the noise plays animportant part too, as the listener?s tolerance of noisein terms of duration is almost twice as great for?slipping noise?as for?creaks?or?raucousness?during the tone onsets. The third paperdescribes the triggering mechanics of a peculiar toneproduction referred to as?Anomalous Low Frequencies?(ALF). If properly skilled, a player can achieve pitches belowthe normal range of the instrument. This phenomenon, analysedand explained through use of computer simulations, is relatedto triggering waves taking?an extra turn?on thestring before causing the string?s release from thebow-hair grip. Since both transverse and torsional propagationspeeds are involved, two different sets of?sub-ranged?notes can be produced this way.