Sonic booms Culprit in recent sonic booms is experimental plane flying 2,000 m.p.h. at 70,000 ft. altitude. Post Mr 19, 1967 p.3 Denver's jet noise tolerance being studied. Post Ag 31, 1967 P-50 Colorado University receives grant to study sonic booms. Post S 9, 1967 p.1 Sonic booms given blame for Mesa Verde slides. RMN Ap 25, 1968 p.5 Post Ap 25, 1968 p.3 CoLoradoans in western part of state complain about sonic booms. Post S 28, 1975 p.26