Julio Estrada, at Miller Theater, in ICE Composer Portraits The woman onstage appears to be struggling. The sounds that are coming out of her are wordless, labored and worrying. A wheezing inhalation. A whispered scream. Choking, gagging, strangled croaks. A high-pitched whine that remains trapped behind her closed lips and masklike face. Many composers today explore the border between music and sound. But the work of Julio Estrada, the subject of the last Composer Portrait of the season at the Miller Theater on Thursday evening, teeters on the threshold between sound and something else. In works like "miqi'cihuatl," for female voice, which here received a mesmerizing performance by Tony Arnold, the thing on the other side of sound is not silence but a primordial state of consciousness, in which emotions manifest themselves in a physical form that is viscerally understood long before it is expressed. On paper, Mr. Estrada, a Mexican composer and mathematician who recently turned 70, cuts a forbidding figure. His Modernist credentials include studies with Nadia Boulanger in Paris, a residence at the Donaueschingen Festival in Germany and theoretical treatises on the relationship of rhythm and pitch. Because of the tortured complexity of his obsessively notated scores (partituras in Spanish), some musicians refer to them as parti-torturas. But Thursday's survey proved that while Mr. Estrada's music is undeniably difficult to play and listen to, it is also wildly entertaining to observe. The theatrical component of Mr. Estrada's works is partly a result of his fascination with ancient Mexican cultures. This comes through not only in the titles of his works - "miqi'cihuatl" combines the Nahuatl words "death" and "woman" - but also in the ritualistic abandon he requires from his performers. It was evident in the declamatory arm gestures and intense facial expressions of Ms. Arnold, which evoked the masks of Mexican folk art. In "ni die saa" (the title means "I do paint music" in Zapotec), which here received its world premiere by the fearless International Contemporary Ensemble, the musicians engaged in a rite of violence against their instruments in which the relatively muted sounds they produced were completely at odds with the furious effort expended. Daniel Lippel held a guitar like a cello, trying to bow it while holding the slackened strings in one fist. Jennifer Curtis held her violin upside-down, pressing a bow into its back. In this unscripted and largely improvised work, the parti-tortura was replaced by the torture of instruments, bringing to mind the trampled violin of Buñuel's "Golden Age." By contrast, in "eolo'oolin," which received a riveting performance by Third Coast Percussion, led and directed by Steven Schick, instruments were liberated, as players paraded clusters of drums around the auditorium. Rhythms morphed into pitch and harmony, creating waves of sound that seemed to coalesce as form. The resonant "Canto naciente" (1978) for brass octet offered a glimpse of an earlier phase of Mr. Estrada's career, when his interest still lay in 12-tone pitch relations. In onstage remarks Mr. Estrada said it was composed "when I still wrote music, before my ear was poisoned by noise." But the title, referring to song coming into being, prefigures his expeditions into the messy, uncomfortable but always fascinating birth of noise.