The "Portrait Trilogy" was completed with "Akhnaten" (1982–1983, premiered in 1984), a vocal and orchestral composition sung in Akkadian, Biblical Hebrew, and Ancient Egyptian. In addition, this opera featured an actor reciting ancient Egyptian texts in the language of the audience. "Akhnaten" was commissioned by the Stuttgart Opera in a production designed by Achim Freyer. It premiered simultaneously at the Houston Opera in a production directed by David Freeman and designed by Peter Sellars. At the time of the commission, the Stuttgart Opera House was undergoing renovation, necessitating the use of a nearby playhouse with a smaller orchestra pit. Upon learning this, Glass and conductor Dennis Russell Davies visited the playhouse, placing music stands around the pit to determine how many players the pit could accommodate. The two found they could not fit a full orchestra in the pit. Glass decided to eliminate the violins, which had the effect of "giving the orchestra a low, dark sound that came to characterize the piece and suited the subject very well". As Glass remarked in 1992, "Akhnaten" is significant in his work since it represents a "first extension out of a triadic harmonic language", an experiment with the polytonality of his teachers Persichetti and Milhaud, a musical technique which Glass compares to "an optical illusion, such as in the paintings of Josef Albers".