Sirena

What it means

A siren is a device that produces a tone by rapidly, periodically interrupting an airstream. A rotating disc with holes releases the air in bursts; the pitch depends on the rotation speed. Because this grows and falls steplessly, the characteristic gliding up and down results. In the orchestra, hand sirens with a crank are used, occasionally also motor-driven devices. The instrument has no fixed pitch; what is notated is the course.

In the notation

The siren is notated in the percussion line, usually graphically: a rising or falling line shows the course, with indications of duration and volume added. An exact pitch range cannot be prescribed, since it depends on the device; the score therefore limits itself to direction and time.

Musical use

The siren entered art music in the early twentieth century, when composers took up noises and sounds of the industrial and urban world into music; the Futurist endeavours of that time belong in this context. Since then it appears in works that deliberately include extra-musical material, as well as in stage and film music as a signal. Its sound cannot be integrated into a harmonic texture; it works as a foreign body and is used precisely for this reason. Sparing use is called for, since even a short entry covers everything else.

Performance practice

Turn the crank evenly and plan the time course precisely: the run-up and run-down each need several seconds, and this time belongs to the musical result. Begin earlier than the notation suggests, so that the tone reaches its intended pitch at the desired moment. Volume can hardly be regulated — clarify, therefore, the placement in the room, to control the effect. Check the mechanism before use for smooth running, and reckon with the sound continuing after release.

Bear in mind that the sound can practically not be integrated into an ensemble sound: plan the passage as an intrusion, not as a component of the texture. Check the position in the room, because it decides the effect, and clarify it with the conductor. Watch the hearing protection of the immediately neighbouring players, since sirens become very loud. Practise the timing with a stopwatch, because the run-up and run-down take several seconds. Check the mechanism before use and keep a spare device ready if the passage is exposed.