Acceptance limits for the duration of pre-Helmholtz transients in bowed string attacks

Abstract

The attack of most bowed notes shows an initial part before Helmholtz triggering occurs ͑the pre-Helmholtz transient͒, during which the stick-slip interaction promotes frequencies other than that of the string's fundamental. Depending on the particular combination of bowing parameters, this state is characterized either by periods that are prolonged, or by a division of the period into two or more parts, multiple flyback. An onset with perfectly periodic motion ͑Helmholtz triggering͒ directly from the very start is also possible. A sample of violin tones representing these three classes of attacks, and with different duration of the pre-Helmholtz transient, has been collected by the use of a computer-controlled bowing machine. The tones were evaluated by 20 advanced string students and professionals in a listening test, judging the acceptance and quality of the attacks. The maximum acceptable duration of the pre-Helmholtz transient was estimated to 50 ms ͑р10 nominal periods, open G string, violin͒ for attacks with prolonged periods, and 90 ms ͑р18 periods͒ for multiple-flyback attacks. These values refer to a neutral start in a neutral context, such as when practicing a scale. A playing test, in which the performances of two professional violinists were analyzed, confirmed these results, and showed that the same limits apply to a larger group of bowing styles as well.

Are there reliable constitutive laws for dynamic friction?

“…This motion, known as the 'Helmholtz motion', involves a single slip in each cycle of stick-slip vibration: see Woodhouse [73] for more details. Violinists have to practice their bowing gestures for a long time to achieve musically satisfactory results, and one of the things they are learning is how to manipulate the bow in order to achieve initial transients that settle into Helmholtz motion quickly [27].…”

“…This can refer to the temporal details of transients, for example at the start of a note on the violin: musical perception of sounds is strongly influenced by transient details, and violinists spend a lot of time practicing to control them (e.g. 27]). In the context of seismology, 'transients' would include the nucleation phase of a major slip.…”

The influence of cellist's postural movements on their musical expressivity

“…De nombreux travaux se sont intéressés à l'influence de l'attaque sur le timbre produit par l'instrument [Woodhouse 1993c, Guettler 1997, Guettler 2002. Cette phase transitoire s'avère en effet être déterminante pour la perception de la qualité et de la "couleur" du son [Pérez Carrillo 2009], que nous développerons plus en détail section 2.1.8.…”

“…Dans [Guettler 1997], trois régimes de vibration transitoires, appelés pré-Helmholtz, sont mis en évi-dence pour différentes combinaisons de force et d'accélération initiale de l'archet. Ces régimes définissent la qualité de l'attaque par rapport aux trois zones de timbre du diagramme de Schelleng (figure 2.6(a)).…”

“…A l'aide d'études psychoacoustiques, [Guettler 1997] a montré que pour rester musicalement acceptable, la durée de l'attaque des sons devait être inférieure à 50ms-90ms en fonction du type de régime pré-Helmholtz. Au delà de ces durées, on perd la hauteur du son, ce qui correspond à un basculement dans l'une des deux zones extrêmes du diagramme de Schelleng (Raucous ou Higher modes).…”