The Hagen Quartett of Salzburg, Austria, ably demonstrated their mastery of both ends of the spectrum of musical style in string quartet playing as they performed in concert on the University of Utah campus Friday night. Playing Mozart, Bartok and a work recently composed for them by Georg Frederich Haas, the four musicians - three of whom are siblings - showed an appreciative crowd why they have a sterling reputation as one of the top quartets in Europe.

The concert opened with an athletic and extroverted performance of Bartok's String Quartet No. 4, written in 1928. The Hungarian genius filled the score for this work with myriad original instrumental effects and couched it in 20th-century counterpoint flavored by folk elements. The quartet played with a deep understanding of the work, accessing the Expressionist angst that underlies its conception.The quartet achieved a fascinating variety of tonal colors as they bowed abrupt clustered chord-strokes; played at the bridge and at the end of the bow; and plucked percussive pizzicato passages in which the strings snapped against the wood.

All of this was executed with marvelous synchronicity despite the intricacy of the shifting rhythms. The third movement stood out for the lyrical solo passages given to each player, set within a context resembling a nocturne. The performance was full of passionate intensity and intellectual challenge.

The Quartet No. 2 by Haas takes the idea of exploration of the aural possiblilties of the instruments several steps further than Bartok did in an esoteric experiment in microtonality - intervals smaller than the half-step. The piece is almost vocal in its conception with its slow glissandos on microtonal chords.

Hearing the work is a most unusual sonar experience, as it is filled with eerie harmonic overtones and a particularly startling growling effect produced by the cello. The quartet achieved a magnificent concentration and unity in producing the subtle effects. The work is composed in one lengthy movement and might tax the patience of the uninitiated listener.

An emotional playing of Mozart's Quartet in G major, K.387 filled out the program. The Hagen Quartett showed that they had no fear of playing it with hearts on sleeves, applying more rubato than has become the recent custom and doing so to excellent expressive effect. The delightfully polyphonic fourth movement was taken at a daring tempo that did not deter the players from achieving extraordinary clarity and definition of every note, even the lightning-paced unison roulades.