Troorkh is a composition for trombone and orchestra by Greek composer Iannis Xenakis. It was commissioned by the Swedish Radio and Rikskonserter and was eventually finished in 1991. It is dedicated to Swedish trombonist Christian Lindberg.
Christian Lindberg traveled to Paris to meet Xenakis for the first time and audition for him. Xenakis told him he didn't have more time, so he asked Xenakis if he could write a trombone concerto for Lindberg. Xenakis declined the proposition and Lindberg went back home. However, he received a composition for solo trombone, Keren, a few years later, in 1985. It required very high skills to be played, so he manage to work on all the difficult passages and sent a recording of the piece to Xenakis. Xenakis replied to him with great satisfaction that he could finish a trombone concerto for him on June 1991.
When Lindberg received Troorkh, he considered it to be "practically unplayable", with 56 high Fs and 2 F-sharps. However, he was ready to premiere it in 1993, in which he received a standing ovation. Subsequently, Xenakis sent him 28 red roses, half a rose each high F, and stated that, in his opinion, Lindberg was the best trombone player at that time. This composition is his last composition for a solo instrument and orchestra.
The title of this composition comes from "trombone" and "orchestra", taking into consideration that the sound of "kh" comes from Ancient Greek. This is a single movement composition and takes 16–20 minutes to perform.
Several analysis methods have been proposed for this composition. As Christian Anders Jallén states, Xenakis treats the orchestra in a dense and opaque way, turning it into only one instruments and not treating it as a combination of instruments. Glissandi and pizzicati, which were his trademarks in early works, are not as present in these late works. The composition starts with a tritone played by the winds. Then, the strings join in playing clusters of music which are further developed afterwards. The composition also features "arborescences", a composition technique developed by Xenakis which consists of "branchings that come off of a rooted tree".