Marco Blaauw from a 2011 Musikfabrik/Oper Koln production of LICHT-BILDER
No. 67 LICHT-RUF (Call from LIGHT)
for trumpet, basset-horn, trombone or other instruments/tape
1995 [at least 5 22" interval signals]

     LICHT is Stockhausen's work for acoustic and electronic operatic forces, divided into the 7 days of the week (one opera for each day).  This opera cycle revolves around 3 archetype characters, MICHAEL, EVE and LUCIFER, and over the 29 hours each of these characters are introduced, come into conflict, face temptation and finally come into union.  The music is almost entirely based on a "super-formula", which is a 3-layered melodic-thematic representation of the 3 characters.  These formula-themes are together and separately threaded throughout the opera's vocal and instrumental fabric.  Story-wise, actors and narrative can (and often do) change from scene to scene, and the libretto text is sometimes made up of non-traditional grammar (or even purely phonetic sounds).

     The super-formula to LICHT is a 3-staff 19-measure piece with the formulas for MICHAEL, EVA and LUCIFER.  These 3 formulas have many special articulations and kinds of ornamentation, but are also expressed throughout LICHT in simplified 9-measure melodic phrases, sometimes referred to as "nuclear formulas".  LICHT-RUF (Call from LIGHT) is a very brief piece which is essentially the first 3 measures of the LICHT nuclear formulas.
LICHT Nuclear formulas
(from "Into the Middleground: Formula Syntax in Stockhausen's LICHT" - Jerome Kohl)
      The 3 measures of LICHT-RUF (the first 3 measures above) are played by 3 instruments and repeated 5 times (or more) with pauses in between.  This can be used a PA announcement signal to the audience to indicate that the opera is about to begin and that they should take their seats.

Sound Impressions
      LICHT-RUF would make a great ring-tone.  Not much more to add there, it's a nice, brief Signal to LIGHT...

Sound sample, CD ordering