The string section consists of instruments that are either bowed, plucked or struck to generate their sound. In a modern orchestra, the majority of the instruments are stringed, and the majority of these are bowed.
The bowed string instruments all work on the same principal which is that a bow fitted with (generally horse) hair is drawn across a string of the instrument causing it to vibrate. This vibration energy is transferred to the bridge, the part suspending the strings over the instrument’s body. The rigid bridge transfers the energy to the top plate or Soundboard which vibrates in sympathy with the bridge and string, generating sound.
The required note is selected by choosing an appropriately tuned string and stopping it at a length required, causing the string to resonate at an agreed frequency coinciding with a point on the musical scale.
The “standard” bowed string family (known as the violin family) consists of the Violin, the Viola, the Cello and the Double Bass (or Contrabass). This family can be extended in the treble and bass by a new family of instruments, the Violin Octet.
Standard tunings of the orchestral violin family are as follows:
- Violin: G D A E (tuned in perfect fifths)
- Viola: C G D A (tuned in fifths, pitched a fourth below a Violin)
- Cello: C G D A (tuned in fifths, pitched an octave below the Viola)
- Double Bass: E A D G (tuned in fourths)
The bowed method of playing allows the musician a great range of expression as, unlike with wind instruments, they don’t need to draw breath and unlike the struck or plucked string instruments, the played note doesn’t decay over time. This allows lengthy and complex legato phrases to be played smoothly, such as this piece from Apocalyptica. A second method of string playing is the pizzicato (pinched or plucked) which gives an immediate and accurate tone, much like a guitar. Here’s the Playful Pizzicato from Britten’s Simple Symphony.
Because of the range of tones and expression available, the strings have the power to overwhelm and emotionally move like no other section. See this from Vivaldi.
Other members of the string family include the Concert Harp, an instrument of 47 plucked strings and the guitar, a six-stringed instrument played by plucking or strumming.