On bowed string instruments, tremolo or “trembling”, usually refers to a rapid succession of up and down bows, most often played at the point or in the upper half of the bow, on a single pitch. Tremolo is usually executed in a back-and-forth motion horizontally, in parallel with the bridge. However, tremolo may also be performed by sweeping the bow up and down the string in a vertical direction, known as spazzolare, meaning “brushed”. This technique can be further adapted into a circular motion, combining both horizontal and vertical activation of the strings, known as arco circolare or “circular bowing”.
The term tremolo has had different meanings over time. An early example of its use in composition for the baroque violin, and meaning multiple repetitions on a single pitch, can be found in the violin part of Biagio Marini’s Affetti Musicali (Marini, 1617, p. 6). It is possible that this early example refers to a measured repetition of the same pitch, perhaps even in a single bow, in the same manner as bow vibrato. A further example of the use of tremolo on the baroque violin followed soon after in Claudio Monteverdi’s Madrigali of 1638 (Monteverdi, 1638, pp. 137–151).
In the 20th century, variations on tremolo began to appear, such as the spazzolare bowing used by Salvatore Sciarrino in the third of his Sei Capricci of 1976 (Sciarrino, 1976, p. 6). Liza Lim’s 1993 solo viola work Amulet employs both spazzolare (Lim, 1993, p. 4) and arco circolare (Lim, 1993, p. 2).
Tremolo, spazzolare, arco circolare on the baroque violin:
Tremolo functions similarly on the baroque violin as on modern string instruments. Each of my historical bows has slight physical strengths and weaknesses for executing tremolo. For instance, my 17th-century-style short bow, although very light at the tip, is designed for crisp articulation and therefore has a very clear tremolo sound. My high-baroque bow, with its convex form and flexible, fluted stick, is less articulate at the point, and requires more right arm activation for tremolo. My classical bow, with its concave shape and heavier hammer-headed point, functions in a similar way to a modern violin bow when playing tremolo.
When performing spazzolare or arco circolare with historic bows, an important physical characteristic must be taken into account. Baroque and classical bows have open frogs, whereas modern bows have a spreader wedge and metal ferule, which are used to hold the bow hair flat, as shown in Figure 9.1 below. This gives modern bows a greater surface area of hair with which to activate the strings. In the absence of a spreader wedge and ferule, the bow hair on baroque and classical bows can bunch together, especially with the motion perpendicular to the length of the hair that is required in spazzolare or arco circolare. This reduces the possible dynamic level of this technique on the baroque violin.
Figure 9.1 – back and front views, from left to right, frog of a modern bow showing full fittings and ferule with spreader wedge underneath holding bow hair flat; open frog of classical bow; and open frog of 17th-century-style short bow
The following is an example of tremolo, followed by spazzolare, followed by arco circolare on the middle strings of the baroque violin, performed with a 17th-century-style short bow.
Video example 9.1 – tremolo, spazzolare, arco circolare on baroque violin
The following is an example of bars 114–119 in Biddy Connor’s The Glass Violin (2018, p. 4). The arco circolare is indicated by the circles with arrows above the stave, and the vertical accents are indicated by the arrows below the stave.
Video example 9.2 – arco circolare with vertical accents in The Glass Violin by Biddy Connor (2018, p. 4), bars 114–119
Figure 9.2 – arco circolare in The Glass Violin by Biddy Connor (2018, p. 4), bars 114–115
For tremolo, strikes through the note stem or, in the absence of a stem, above or below the note, as in notation for demi-semiquavers. For spazzolare, the same as tremolo with added up and down arrows above. For arco circolare, the same as tremolo with added spirals or series of circles above the relevant notes, as in Figure 9.3 below.
Figure 9.3 – example of a possible notation for tremolo, followed by spazzolare, followed by arco circolare